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S. HRG. 111–703 

FLOODING IN BISMARCK/MANDAN AREAS OF 

NORTH DAKOTA 

HEARING 

BEFORE A

SUBCOMMITTEE OF THE 

COMMITTEE ON APPROPRIATIONS 

UNITED STATES SENATE 

ONE HUNDRED ELEVENTH CONGRESS 

FIRST SESSION 

SPECIAL HEARING 

NOVEMBER 11, 2009—BISMARCK, ND 

Printed for the use of the Committee on Appropriations 

( 

Available via the World Wide Web: http://www.gpo.gov/fdsys 
(II) 

COMMITTEE ON APPROPRIATIONS 

DANIEL K. INOUYE, Hawaii, Chairman 

ROBERT C. BYRD, West Virginia 

PATRICK J. LEAHY, Vermont 

TOM HARKIN, Iowa 

BARBARA A. MIKULSKI, Maryland 

HERB KOHL, Wisconsin 

PATTY MURRAY, Washington 

BYRON L. DORGAN, North Dakota 

DIANNE FEINSTEIN, California 

RICHARD J. DURBIN, Illinois 

TIM JOHNSON, South Dakota 

MARY L. LANDRIEU, Louisiana 

JACK REED, Rhode Island 

FRANK R. LAUTENBERG, New Jersey 

BEN NELSON, Nebraska 

MARK PRYOR, Arkansas 

JON TESTER, Montana 

ARLEN SPECTER, Pennsylvania 

THAD COCHRAN, Mississippi 

CHRISTOPHER S. BOND, Missouri 

MITCH MCCONNELL, Kentucky 

RICHARD C. SHELBY, Alabama 

JUDD GREGG, New Hampshire 

ROBERT F. BENNETT, Utah 

KAY BAILEY HUTCHISON, Texas 

SAM BROWNBACK, Kansas 

LAMAR ALEXANDER, Tennessee 

SUSAN COLLINS, Maine 

GEORGE V. VOINOVICH, Ohio 

LISA MURKOWSKI, Alaska 

CHARLES J. HOUY, Staff Director 

BRUCE EVANS, Minority Staff Director 

SUBCOMMITTEE ON ENERGY AND WATER DEVELOPMENT

BYRON L. DORGAN, North Dakota, Chairman 

ROBERT C. BYRD, West Virginia 

PATTY MURRAY, Washington 

DIANNE FEINSTEIN, California 

TIM JOHNSON, South Dakota 

MARY L. LANDRIEU, Louisiana 

JACK REED, Rhode Island 

FRANK R. LAUTENBERG, New Jersey 

TOM HARKIN, Iowa 

JON TESTER, Montana 

DANIEL K. INOUYE, Hawaii, (ex officio) 

ROBERT F. BENNETT, Utah 

THAD COCHRAN, Mississippi 

MITCH MCCONNELL, Kentucky 

CHRISTOPHER S. BOND, Missouri 

KAY BAILEY HUTCHISON, Texas 

RICHARD C. SHELBY, Alabama 

LAMAR ALEXANDER, Tennessee 

GEORGE V. VOINOVICH, Ohio 

Professional Staff 

DOUG CLAPP

ROGER COCKRELL

FRANZ WUERFMANNSDOBLER

CAROLYN E. APOSTOLOU (Minority) 

TYLER OWENS (Minority) 

Administrative Support 

MOLLY BARACKMAN-EDER
(III) 

C O N T E N T S 

Page 

Statement of Senator Byron L. Dorgan ................................................................. 1 

Statement of Colonel Robert J. Ruch, District Commander, Omaha District, 

Corps of Engineers—Civil, Department of the Army, Department of Defense—Civil ........................................................................................................... 3 

Prepared Statement ......................................................................................... 6 

Statement of Hon. John Warford, Mayor, Bismarck, North Dakota ................... 8 

Prepared Statement ......................................................................................... 10 

Statement of Hon. Timothy A. Helbling, Mayor, City of Mandan, North Dakota ........................................................................................................................ 11

Prepared Statement ......................................................................................... 12 

Statement of Ken Royse, Chairman, Missouri River Joint Water Resource 

Board ..................................................................................................................... 13 

Prepared Statement ......................................................................................... 16 

Statement of Michael Gunsch, District Engineer, Burleigh County Water 

Resource District .................................................................................................. 17 

U.S. Army Corps of Engineers Omaha District—Oahe-Bismarck Area Studies .......................................................................................................................... 19 

Summary of the Flood Potential ............................................................................. 20 

Existing Conditions ................................................................................................. 21 

Future Conditions .................................................................................................... 23 

The Alternatives ...................................................................................................... 27 

Channel Dredging .................................................................................................... 28 

Channel Cutoffs ....................................................................................................... 29 

Bank Stabilization ................................................................................................... 30 

Levees ....................................................................................................................... 31 

Garrison Operational Changes ............................................................................... 32 

Oahe Operational Changes ..................................................................................... 34 

Land Acquisition ...................................................................................................... 35 

Flood Plain Management ........................................................................................ 35 

Impacts of Siltation of the Missouri River in the State of North Dakota 

Summary Report .................................................................................................. 41 

Appendix A—Identification of Sources and Deposits and Locations of Erosion 

and Sedimentation ............................................................................................... 57 

Appendix B—Economic Impact of Sedimentation and Erosion Along the Missouri River, North Dakota ................................................................................... 90 

Appendix C—Impacts of Siltation of the Missouri River on Recreation in 

North Dakota ........................................................................................................ 114 

Appendix D—Impact of Siltation on Hydropower Generation, Missouri River, 

North Dakota ........................................................................................................ 128 

Appendix E—Impact of Silation of the Missouri River on Fish and Wildlife 

in North Dakota ................................................................................................... 179 

Appendix F—Impact of Siltation on Flood Control Missouri River, North 

Dakota ................................................................................................................... 196 

Appendix G—Impacts of Siltation of the Missouri River on Indian and NonIndian Historical and Cultural Sites in North Dakota ..................................... 218 

Exhibit 1—Legal Sections in Files and Literature Search ................................... 242 

Exhibit 2—Glossary of Archaeological Terms ....................................................... 243 

Exhibit 3—Environmental Compliance Requirements ......................................... 243 

Missouri River Flood Hazard Mitigation—Bismarck/Mandan Project Summary and Risk Assessment—Deadfall Tree Removal Grant Application ........ 245 

Project Description .................................................................................................. 245 

Project Purpose ........................................................................................................ 246 

Opinion of Probable Cost ........................................................................................ 246 

Benefit—Cost Ratio Determination ........................................................................ 246 
Page

IV 

Summary Notes ....................................................................................................... 248 

Acknowledgments of Data Sources ......................................................................... 248 

Appendix A—Aerial and Field Reconnaissance Photo Record ............................. 249 

Prepared Statement of Michael Gunsch ................................................................ 264 

Appendix F—Impact of Siltation on Flood Control, Table 3.1—Flood Elevation 

Comparison ........................................................................................................... 265 

Statement of Dale Frink, State Engineer, North Dakota State Water Commission ........................................................................................................................ 275 
(1) 

FLOODING IN BISMARCK/MANDAN AREAS OF 

NORTH DAKOTA 

WEDNESDAY, NOVEMBER 11, 2009 

U.S. SENATE, SUBCOMMITTEE ON ENERGY AND WATER DEVELOPMENT, COMMITTEE ON APPROPRIATIONS, Bismarck, ND. 

The subcommittee met at 7:15 p.m., in the Bismarck City Commission Room, Bismarck, ND, Hon. Byron L. Dorgan (chairman) 

presiding. 

Present: Senator Dorgan. 

STATEMENT OF SENATOR BYRON L. DORGAN

Senator DORGAN. Ladies and gentlemen, we’d like to begin the 

hearing. This is a hearing of the United States Senate Energy and 

Water Appropriations Subcommittee. I’m Senator Byron Dorgan, 

chairman of that subcommittee. 

I’m joined by Roger Cockrell, who is the professional staff member on the water side of that subcommittee and works on the water 

issues across the United States and knows more about water than 

most anybody in the United States Senate. 

Justin Schardin is also with me, who works on my personal staff 

on water and other related issues. 

I wanted to indicate as well representatives of Senator Conrad’s 

staff and Congressman Pomeroy’s staff are with us, Russ Keys is 

in the back of the room. Russ, could you stand? 

And Marty Beckell is here from Senator Conrad’s office. 

I appreciate both of them being with us today. Obviously on 

North Dakota issues I work very closely with Congressman Pomeroy and Senator Conrad. 

This is a field hearing of the Energy and Water Subcommittee. 

What we will do is take testimony, and following that testimony we 

will also accept in the permanent hearing record any submissions 

for 2 weeks following tonight. You may submit them to the United 

States Senate, care of my office or to the Senate Energy and Water 

Appropriations Subcommittee. They will be made a part of the permanent record. 

I want to explain to you what we’re trying to do and why I’m 

here. After what happened last spring in North Dakota with a very 

substantial amount of flooding many parts of our State, we, of 

course, became very active on the Red River, particularly in the 

Fargo/Moorhead area and other related areas of flooding on the 

Red River. I’m sure it was not lost on everybody in North Dakota 

that we came very close to having a significant, significant devasta-
2 

tion of the largest population center as a result of a record flood. 

But the levees held. Through a heroic flood fight, much less damage was done than could have been. 

So we’ve spent a lot of time thinking about and working on and 

working with local government officials with respect to flood control 

on the Red River. We have also now, as a result of the chronic 

flooding that happened in Valley City and Jamestown and in other 

areas on the Sheyenne and the James, we’ve initiated certain studies with respect to both the Sheyenne River system and the James 

River system. And with the Corps of Engineers we are working 

through a reconnaissance study on both river systems right now. 

I just put the money in the appropriations bill. The President 

just signed my legislation the Energy and Water Appropriations 

bill just days ago. And that includes sufficient funding for a reconnaissance study on the James River system and the Sheyenne 

River system. Obviously that’s because substantial flooding events 

occurred in some very large cities, especially on both river systems. 

The questions today are what happened with respect to flooding 

in and around Bismarck, North Dakota last spring. 

What happened? 

What caused it? 

What were the consequences? 

Was it a once in a lifetime event that was a perfect storm or was 

it something that could happen again? 

If so, what are the odds of it happening again? 

If so, what kinds of things can be done to minimize the chances 

of it happening again? 

I was here, along with my colleagues during that period. And I 

understood that the folks here in the Bismarck/Mandan region 

spent a lot of sleepless nights trying to figure out what on earth 

was happening. And how do you respond to it? Ice jams and a 

whole series of things on this Missouri River that were very significant and could have had a devastating impact on these communities. Now it had an impact on some people’s houses and so on, 

but the impact was less than it could have been had the worst 

fears been imagined. 

So the questions for this hearing tonight are, what were the 

causes of the flooding this spring? 

What was done to mitigate the flooding during the event? 

What can be done in the future to prevent this type of flooding 

from happening again here in the Bismarck/Mandan area? 

The flood control process, if in fact the conclusion of this hearing 

is that there needs to be some mechanism by which some flood control projects are developed or some means of flood control would be 

achieved, is a bottom up process. By that I mean just as in Fargo 

and Moorhead, the Federal Government doesn’t come in and say to 

them here’s the kind of project you ought to have. What happens 

is the local people decide here’s the kind of project that we think 

we need. 

Then we begin a reconnaissance study then a feasibility study to 

determine whether or not there is a Federal interest. If so, do we 

meet the cost benefit ratio? There has to be a number of criteria 

that are met. 
3 

If there is a project that is seen to benefit a region that would 

reduce the prospect of flooding, it has to be three things. 

It has to be technically sound. In other words, it has to be 

buildable, No. 1. It must be operable by a non-Federal entity once 

it’s built. 

No. 2, it has to be environmentally sustainable. That means that 

the environment of the impacted area is not degraded by the construction of a project. 

No. 3, it has to be economically viable. That is, for the Federal 

Government to participate in any kind of a project, the plan the 

Corps would recommend would have to have a minimum of $1 of 

benefit for every dollar that is invested. 

So all of those things are part of a discussion that we will hear 

tonight, again, what happened? 

What do we think caused it? 

What are the consequences or what is the likelihood of it happening again? 

What kinds of things can be done to minimize the chance of it 

happening again? 

With that we have Colonel Ruch, the Commander of the Corps 

of Engineers Omaha District, who has come up to join us. Colonel, 

we appreciate your being here. 

We will hear from the Honorable John Warford, the mayor of 

Bismarck, North Dakota. 

We will also hear from the Honorable Tim Helbling, the mayor 

of Mandan. 

We’ll also hear from Ken Royse, the Chairman of the Missouri 

River Joint Water Resources Board and Mike Gunsch, the engineer 

for the Burleigh County Water Resource District. 

I appreciate very much all of you being here on time and ready 

to go. We will begin with you, Colonel Ruch and then we’ll go down 

the line. I intend to ask a series of questions. Hopefully we can get 

on the record all that we need to have on the record. 

I will, depending on time, be willing to entertain some comments 

from the audience following the statements and my questions. I 

would do that on the basis that you would give us your name and 

put your statement on the record. I would want to do that with a 

minimum number if we can. 

But I’m here because I want to hear all of you. We’ve selected 

the witnesses that I think will represent the opinion and the interest of the region. 

Colonel Ruch, thank you. You may proceed. Your entire statement, as will be the case with all witnesses, will be part of the permanent record, so you may summarize. 

STATEMENT OF COLONEL ROBERT J. RUCH, DISTRICT COMMANDER, 

OMAHA DISTRICT, CORPS OF ENGINEERS—CIVIL, DEPARTMENT 

OF THE ARMY, DEPARTMENT OF DEFENSE—CIVIL 

Colonel RUCH. Thank you, Senator. Chairman Dorgan, my name 

is Colonel Robert J. Ruch, Commander of the Omaha District, U.S. 

Army Corps of Engineers. Thank you for the opportunity to testify 

today on 2009 flooding in central and south—— 

Senator DORGAN. Is your microphone turned on, Colonel? 

Colonel RUCH. It is. 

Senator DORGAN. It is? Ok. Would you pull it a little closer? 
4 

Colonel RUCH. I wanted to show you that emergency operations 

in disaster response have the utmost importance at the Corps of 

Engineers. It was identified by the Chief of Engineers as our number one campaign goal. And we stand ready to respond on a moment’s notice to contingency operations worldwide in support of 

natural disasters as well as combat and stabilizing operations. 

I’d like to give you a brief run down on the conditions leading 

to this year’s floods. 

How the Corps responded to the request for assistance. 

And the summary to post flood coordination. 

This year’s flooding in North Dakota was a direct result of historic snow over the winter of 2008–09. Many communities in the 

central part of the State, including Bismarck, recorded more than 

100 inches of snow. Rapid melting and spring rains resulted in 

widespread flooding on the Missouri River, the Knife River, the 

Cannonball and Beaver Creek as well as other streams and tributaries. 

With forecasts for high tributary runoff below Garrison Dam, the 

Missouri River Water Management Office in Omaha began with 

close coordination with the State of North Dakota and managers of 

water supply intakes, powerplants and other interest along the 

river upstream from Bismarck. A substantial ice jam in the Missouri River south of Bismarck on March 23, 2009 prompted a request for Corps technical assistance. We deployed ice jam experts 

from both the Omaha District and the Cold Regions Research and 

Engineering Laboratory in Hanover, New Hampshire to advise 

North Dakota emergency management officers on blasting the jam 

and other measures to relieve flooding. 

Concurrently another significant ice jam formed upstream from 

Bismarck raising concerns that this jam could break free and move 

downstream to join the other one. To alleviate the threat, the Corps 

collaborated with the State to make the unprecedented decision to 

cut all releases from the Garrison Dam, while the downstream jam 

was blasted and allowed to break up. 

One hundred miles east of Bismarck rapid snow melt exacerbated by spring rains resulted in projected runoff in the James 

River in excess of the 1997 record pool elevation of both Pipestem 

and Jamestown reservoirs. Engineers from the Corps, the Bureau 

of Reclamation and the National Weather Service analyzed mountain runoff scenarios. The forecast predicted that both dams would 

see elevations which would overtop the spillway crests resulting in 

unregulated releases downstream and the potential for significant 

flooding. 

Due to early coordination with the State, the city of Jamestown 

and other communities in North Dakota officially requested assistance from the Corps in early March. In response we constructed 

advance measures in Jamestown, LaMoure and Ludden. These 

measures consisted of temporary levees and flood walls, interior 

drainage pumps and 24 hour surveillance and monitoring on both 

of the dams. 

Forecasts for combined releases from both reservoirs were projected to exceed 4,000 cubic feet per second which was more than 

double the record of 1,800 cubic feet per second set during the 1997 

event. Releases were gradually increased to a maximum of 3,200 
5 

cubic feet per second in late April. They were held steady at that 

level due to serious infiltration problems with the city’s sewer system at higher levels. Releases remained at 3,200 for approximately 

a month. And then were gradually reduced back to normal levels. 

After the flood threat had passed and the reservoirs were sufficiently drawn back down to more normal levels, all the temporary 

measures were removed. Reservoir storage evacuation was completed by late August. The event lasted 133 days. 

Overall the Omaha District committed 177 personnel and expended $7.7 million in emergency funding, $2.4 million in FEMA 

debris funding, constructed 4.5 miles of temporary levees and 

floodwalls in Jamestown and 4,600 feet of temporary structures in 

LaMoure. 

We deployed more than 1.35 million sandbags, 10 pumps, and 

14,000 feet of Hesco Bastions, 3,300 feet of Rapid Deployable 

Floodwall, and Portadam products as well. 

These efforts prevented an estimated $70 million in damages. 

Homes and businesses in Jamestown and LaMoure were not 

flooded. 

As the reservoirs dropped and the James River receded, personnel from our Garrison and Oahe projects were instrumental in 

opening the lines of communications regarding Corps authorities 

and programs, which could address flood risks on a long-term 

basis. The Corps has an array of authorities and programs that 

may assist local communities with addressing flood risks. As a result of this year’s flooding, the Omaha District has received numerous requests from communities in North Dakota, Jamestown, 

Stutsman County, Emmons County and Mercer County. We have 

initiated coordination meetings with these communities and have 

already conducted site visits to a few with more scheduled in the 

weeks to come. 

Also the State of North Dakota, FEMA, and the Corps have been 

developing a charter to establish a Silver Jackets Program for the 

State. The Silver Jackets Program will establish a coordinating 

committee to help maintain communications and serve as a clearinghouse for prioritizing activities among the various agencies. I 

want to commend the State for taking this initiative. I believe that 

the visibility that comes with this designation will position the various projects within the State to better compete for the limited 

State and Federal resources. 

The Energy and Water Development Appropriations Act of 2010 

includes $150,000 for the Upper James River. We will soon begin 

coordination with State and local officials to decide how best to proceed with the study. 

Also on the James, the Corps allocated $127,000 from the American Recovery and Reinvestment Act funding, which has been used 

to develop a new hydrologic forecasting model for the James River 

upstream from the Jamestown and Pipestem Dams and downstream to LaMoure. 

The dam safety program has received funding for detailed topographic mapping of the shorelines of the two reservoirs and along 

the entire James River floodplain from the dams downstream to 

the North Dakota/South Dakota State line. The new mapping is 
6 

scheduled for acquisition this fall with final delivery of the maps 

in June 2010. 

In addition we continue to work with the North Dakota Task 

Force on Missouri River Restoration initiatives. Under that authority we completed an assessment report this past June to help identify sedimentation issues and concerns along the Missouri River. 

We are currently working with the Task Force to develop a plan 

for moving forward with projects. 

Finally on October 1, 2009 we initiated a new study to re-examine the original authorized purposes of the Missouri River of the 

Flood Control Act of 1944, also known as the Pick-Sloan Plan. The 

study was authorized by section 108 of the Omnibus Appropriations Act of 2009. It is anticipated that the cost will be $25 million 

to complete. 

PREPARED STATEMENT

The overall purpose of the study is to ‘‘review the original project 

purposes based on the Flood Control Act of 1994 . . . to determine 

if changes to the authorized project purposes and existing Federal 

water resource infrastructure may be warranted.’’ We are currently 

developing a Project Management Plan and are in the midst of collecting preliminary stakeholder and public input on the engagement strategies in order to develop a comprehensive, public involvement plan. Formal scoping of the project is scheduled to commence in April 2010. This study will be a major Corps undertaking, 

co-led by the Omaha and Kansas City Districts. And we plan to 

work with State, local, tribal and public interests throughout its 

duration. 

Chairman Dorgan, I appreciate the opportunity to be here today. 

And I’d be happy to answer any questions. 

[The statement follows:] 

PREPARED STATEMENT OF COLONEL ROBERT J. RUCH

Chairman Dorgan, my name is Colonel Robert J. Ruch, Commander of the Omaha 

District, U.S. Army Corps of Engineers. Thank you for the opportunity to testify 

today on the 2009 flooding in central and southeastern North Dakota. 

I want to assure you that emergency operations and disaster response are of upmost importance to the Corps of Engineers. It was identified by the Chief of Engineers as our No. 1 Campaign Goal, and we stand ready to respond on a moments 

notice to contingency operations worldwide in support of natural disasters as well 

as combat and stabilizing operations. 

I would like to give a brief rundown of the conditions leading to this year’s floods, 

how the Corps responded to requests for assistance, and a summary of post flood 

coordination. 

This year’s flooding in North Dakota was a direct result of historic snow over the 

winter of 2008–2009. Many communities in the central part of the State, including 

Bismarck, recorded more than 100 inches of snow. 

Rapid melting, exacerbated by spring rains, resulted in widespread flooding on the 

Missouri River, the Knife River, Cannonball River, and Beaver Creek as well as 

many other streams and tributaries. With forecasts for high tributary runoff below 

Garrison Dam, the Missouri River Water Management Office in Omaha began close 

coordination with the State of North Dakota and managers of water supply intakes, 

power plants, and other interests along the river upstream from Bismarck. 

A substantial ice jam in the Missouri River south of Bismarck on March 23, 2009 

prompted a request for Corps technical assistance. We deployed ice jam experts from 

both the Omaha District and the Cold Regions Research and Engineering Laboratory in Hanover, New Hampshire to advise North Dakota Emergency Management 

officers on blasting the jam and other measures to relieve flooding. 
7 

Concurrently, another significant jam formed upstream from Bismarck, raising 

concerns that this jam could break free and move downstream to join the other one. 

To alleviate the threat, the Corps collaborated with the State to make the unprecedented decision to cut all releases from Garrison Dam while the downstream jam 

was blasted and allowed to break up. 

A hundred miles east of Bismarck, rapid snow melt, exacerbated by spring rains, 

resulted in projected runoff in the James River in excess of the 1997 record pool 

elevations of both Pipestem and Jamestown Reservoirs. As engineers from the 

Corps, Bureau of Reclamation, and National Weather Service analyzed melt and 

runoff scenarios, the forecasts predicted that both dams could see elevations, which 

would overtop their spillway crests resulting in unregulated releases downstream 

and the potential for significant flooding. 

Through early coordination with the State, city of Jamestown, and other communities, North Dakota officially requested assistance from the Corps in early March. 

In response, we constructed Advanced Measures in Jamestown, LaMoure, and 

Ludden. These measures consisted of temporary levees and floodwalls, interior 

drainage pumps, and 24-hour surveillance and monitoring on both dams. 

Forecasts for combined releases from both reservoirs were projected to exceed 

4,000 cubic feet per second (cfs), more than double the record of 1,800 cfs set during 

the 1997 event. Releases were gradually increased up to a maximum of 3,200 cfs 

in late April. They were held steady at that level due to serious infiltration problems with the city’s sewer system at higher levels. 

Releases remained at the 3,200 cfs level for approximately a month and then were 

gradually reduced back to normal levels. After the flood threat had passed and the 

reservoirs were sufficiently drawn back to more normal levels, all the temporary 

measures were removed. Reservoir storage evacuation was completed by late August. 

The event lasted 133 days. Overall, Omaha District committed 177 personnel and expended $7.7 million in emergency funding, $2.4 million in FEMA debris funding, 

constructed 4.5 miles of temporary levees and floodwalls in Jamestown and 4,600 

feet of temporary structures in LaMoure. We deployed more than 1.35 million sandbags, 10 pumps, and 232 rolls of plastic sheeting, as well as 14,000 feet of Hesco 

Bastions, 3,300 feet of Rapid Deployable Floodwall, and 1,250 linear feet of 

Portadam products. These efforts prevented an estimated $70 million in damages. 

Homes and business in Jamestown and LaMoure were not flooded. 

As the reservoirs dropped and the James River receded, personnel from our Garrison and Oahe projects were instrumental in opening the lines of communications 

regarding Corps authorities and programs, which could address flood risks on a 

long-term basis. The Corps has an array of authorities and programs that may assist local communities with addressing flood risks. As a result of this year’s flooding, 

the Omaha District has received numerous requests from communities in North Dakota (Jamestown, Stutsman County, Emmons County and Mercer County). We have 

initiated coordination meetings with these communities and have already conducted 

site visits to a few with more scheduled in the weeks to come. 

Also the State of North Dakota, FEMA, and the Corps have been developing a 

charter to establish a Silver Jackets Program for the State. The Silver Jackets Program will establish a coordinating committee to help maintain communications and 

serve as a clearinghouse for prioritizing activities among the various agencies. I 

want to commend the State for taking this initiative. I believe that the visibility 

that comes with Silver Jackets designation will position the various projects within 

the State to better compete for limited State and Federal resources. 

The Energy and Water Development Appropriations Act of 2010 includes $150,000 

for the Upper James River. We will soon begin coordination with State and local 

officials to decide how best to proceed with the study. 

Also on the James River, the Corps allocated $127,000 from the American Recovery and Reinvestment Act funding, which has been used to develop a new hydrologic 

forecasting model for the James River upstream from the Jamestown and Pipestem 

Dams and downstream to LaMoure. 

The dam safety program has received funding for detailed topographic mapping 

of the shorelines of the two reservoirs and along the entire James River floodplain 

from the dams downstream to the North Dakota—South Dakota State line. The new 

mapping is scheduled for acquisition this fall with final delivery of the maps in June 

2010. 

In addition, we continue to work with the North Dakota Task Force on Missouri 

River Restoration initiatives. Under that authority we completed an Assessment Report this past June to help identify sedimentation issues and concerns along the 

Missouri River. We are currently working with the Task Force to develop a plan 

for moving forward with projects. 
8 

Finally, on October 1, 2009 we initiated a new study to re-examine the original 

authorized purposes (Missouri River) of the Flood Control Act of 1944 also known 

as the Pick-Sloan Plan. The study was authorized by section 108 of the Omnibus 

Appropriations Act of 2009 and is anticipated to cost $25 million to complete. The 

overall purpose of the study is to ‘‘review the original project purposes based on the 

Flood Control Act of 1944 . . . to determine if changes to the authorized project 

purposes and existing Federal water resource infrastructure may be warranted.’’ We 

are currently developing a Project Management Plan, and are in the midst of collecting preliminary stakeholder and public input on engagement strategies in order 

to develop a comprehensive public involvement plan. Formal scoping of the project 

is scheduled to commence in April 2010. This study will be a major Corps undertaking, co-led by Omaha and Kansas City Districts, and we plan to work with State, 

local, tribal, and public interests throughout its duration. 

Chairman Dorgan, I appreciate the opportunity to be here today and I will be 

happy to answer any questions you may have. 

Senator DORGAN. Colonel, thank you very much. 

The study of the Missouri River in section 108 is a study that 

I wrote and have funded. I look forward to substantial results from 

that study. I know it’s going to take several years, but at last, at 

long, long last we need to understand what the management of this 

river should be given the realities of the use of the river. 

I would just observe that in circumstance and at times when 

we’ve been short of water and we’re moving water out of the upstream dams in order to support one barge that’s floating downstream hauling sand and gravel. You scratch your head and ask 

yourself, you know, where’s the common sense here? So that’s a 

study that I wrote and am funding. I look forward to have some 

results for the next several years. 

Mayor Warford, welcome. It’s good to see you. You may proceed. 

STATEMENT OF HON. JOHN WARFORD, MAYOR, BISMARCK, NORTH 

DAKOTA 

Mr. WARFORD. Thank you very much, Senator Dorgan and members of the subcommittee, I want to thank you for allowing me to 

share Bismarck’s spring 2009 Missouri River flooding experiences 

with you this evening. 

I’m proud to tell you that Bismarck’s emergency responders performed well during our flood crisis. They used their training and 

abilities to deal effectively with our emergency. Invaluable assistance was also received throughout the flood event from North Dakota Disaster Response and Water Management agencies. However 

since the subject of this hearing is the Federal response to the 

event my comments will be directed primarily for the Federal resources utilized in dealing with the flood. 

Bismarck benefitted greatly from superb communication between 

the North Dakota State Water Commission and the U.S. Army of 

Corps of Engineers. This communication resulted in a very timely 

decision by the Corps to hold releases from Garrison Dam to an absolute minimum for several days to allow ice jams in the Bismarck/ 

Mandan area of the Missouri River to clear. This quick response 

potentially saved lives and unquestionably averted major property 

damage. 

Bismarck and its citizens benefitted from the quick attention of 

the Federal Emergency Management Agency also who arrived as 

soon as the flood emergency was evident. They came ready to help 

with expertise and financial resources. The National Weather Service and the Army Corps of Engineers gave Bismarck immediate as-
9 

sistance in those most difficult days when the river and the weather were foremost in everyone’s minds. 

Bismarck benefitted greatly from the assistance of the Congressional delegation of the Governor. Several times each day phone 

calls were received from political leaders offering to help. Senators 

Dorgan and Conrad, Congressman Pomeroy and Governor Hoeven 

and yes, President Obama were available, although the President 

did require the use of a cell phone. The attention given to our citizens of our city at that time by our political leaders was greatly 

appreciated and showed concern and support during some pretty 

tough days. 

The superb report of the North Dakota National Guard is worthy 

of special recognition. Given the opportunity to utilize Federal and 

State resources the National Guard was invaluable in our flood response. The Guard’s presence was visible, accommodating and 

steady throughout the disaster. From sandbag operations to evacuation to aerial recognizance to bringing in an explosives team, the 

Guard provided for many pressing needs. 

In the time available I cannot begin to thank everyone who went 

out of their way to assist us in this most difficult time. They helped 

pave the way for the recovery we have enjoyed. This was an amazing team effort, one that I’m intensely proud of to claim on behalf 

of our city. 

As in the case with every crisis, part of our responsibility is to 

look at what might have been done to lessen the severity of the crisis and to prevent a reoccurrence. This is always done in 20/20 

hindsight. But it is a necessary part of a disaster autopsy. 

So the spring 2009 Missouri flood in the Bismarck area was 

largely caused by ice jamming and heavy spring runoff, much of it 

from the Missouri River tributaries such as the Heart and Knife 

Rivers. Apple Creek, though not a factor in 2009 could potentially 

impact an ice jam crisis. If the ice conditions in the tributaries 

could be more closely monitored and their impacts on the Missouri 

anticipated and possibly mitigated. I think we could avoid an ice 

jam event of this proportion. 

If the tributary contribution to Missouri were able to be managed 

more completely an additional advantage would be gained. However, if no physical event were changed. A more thorough monitoring of tributary conditions would allow an earlier warning of 

problems that could affect the Missouri. 

A second recommendation of an aide might be the addition of a 

Missouri River State Management Device or devices. So an ice jam 

in the headwaters of the Oahe stretch of the river could more 

quickly be detected. Lowland flood warnings could be given on a 

more accurate and timely basis. Since ice jams are very difficult 

and hard to predict additional river condition monitoring systems 

may allow officials to issue earlier warnings to residents. 

Another recommendation would involve the preparation and testing of an ice jam response plan. The city would be a very willing 

contributor to the development of this plan. But it lacks the expertise in ice jam fighting or response to rapid river stage increases 

caused by flooding associated with ice jams. The assistance of Federal and State resources would aid greatly in this planning effort. 
10 

A fourth suggestion would involve a study of the vulnerable 

areas south of Bismarck and ways in which either a temporary or 

permanent dike system might aid in the prevention of flooding 

from the Missouri River or Apple Creek. This study should focus 

on a catastrophic ice jam on the Missouri similar to the spring of 

2009 event and consider the additive effect of a high Apple Creek 

flow that might not be able to discharge into the Missouri River. 

A final recommendation recognizes that prevention of a disaster 

is a proven desire of everyone who has experienced the pain and 

loss caused by such an event. While this is never entirely possible, 

it is reasonable to consider actions that will eliminate the event or 

make it less costly. It would be desirable to consider dredging the 

headwaters of the Oahe. Chronic bank erosion and resulting siltation of the quiet waters of the Oahe have caused many sandbars 

and a winding river channel. This makes ice jamming an increasingly frequent phenomenon. 

PREPARED STATEMENT

Senator Dorgan, again, thank you once again for the opportunity 

to discuss this spring 2009 flood event in the Bismarck area. The 

resources you have provided to us have done a great deal to mitigate the problem. And your willingness to assist with further mediation of the threat is deeply appreciated. Thank you. 

[The statement follows:] 

PREPARED STATEMENT OF HON. JOHN WARFORD

Thank you for allowing me to share Bismarck’s spring 2009 Missouri River flood 

experiences with you this evening. 

I am proud to tell you that Bismarck’s emergency responders performed well during our flood crisis. They used their training and abilities to deal effectively with 

our emergency. Invaluable assistance was also received throughout the flood event 

from North Dakota disaster response and water management agencies. However, 

since the subject of this hearing is the Federal response to this event, my comments 

will be directed primarily toward the Federal resources utilized in dealing with the 

flood. 

Bismarck benefitted greatly from superb communication between the North Dakota State Water Commission and the Army Corps of Engineers. This communication resulted in a very timely decision by the Corps to hold releases from the Garrison Dam to an absolute minimum for several days to allow ice jams in the Bismarck-Mandan area of the Missouri River to clear. This quick response potentially 

saved lives and unquestionably averted major property damage. 

Bismarck and its citizens benefitted from the quick attention of the Federal Emergency Management Agency who arrived as soon as the flood emergency was evident. 

They came ready to help with expertise and financial resources. The National 

Weather Service and the Army Corps of Engineers gave Bismarck immediate assistance in those most difficult days when the river and the weather were foremost in 

everyone’s minds. 

Bismarck benefitted greatly from the assistance of the congressional delegation 

and the Governor. Several times each day phone calls were received from political 

leaders offering to help. Senators Dorgan and Conrad, Representative Pomeroy, 

Governor Hoeven and yes, President Obama, were available for press briefings, although the President did require the use of a cell phone. The attention given to the 

citizens of our city at this time by our political leaders was greatly appreciated and 

showed concern and support during some pretty tough days. 

The superb support of the North Dakota National Guard is worthy of special recognition. Given the opportunity to utilize Federal and State resources, the National 

Guard was invaluable in our flood response. The Guard’s presence was visible, accommodating and steady throughout the disaster. From sandbag operations to evacuation, to aerial reconnaissance, to bringing in an explosives team; the Guard provided for many pressing needs. 
11 

In the time available I cannot begin to thank everyone who went out of their way 

to assist us in this most difficult time. They helped pave the way for the recovery 

we have enjoyed. This was an amazing team effort; one that I am intensely proud 

to claim on behalf of the city. As is the case with every crisis, part of our responsibility is to look at what might have been done to lessen the severity of the crisis 

and to prevent a recurrence. This is always done with 20 by 20 hindsight, but it 

is a necessary part of a disaster autopsy. 

The spring 2009 Missouri River flood in the Bismarck area was largely caused by 

ice jamming, much of it from Missouri River tributaries such as the Heart and Knife 

Rivers. Apple Creek, though not a factor in 2009, could potentially impact an ice 

jam crisis. If the ice conditions in the tributaries could be more closely monitored 

and their impacts on the Missouri anticipated and possibly mitigated, I think we 

could avoid an ice jam event of this proportion. If the tributary contribution to the 

Missouri were able to be managed more completely, an additional advantage would 

be gained. However, if no physical event were changed, a more thorough monitoring 

of tributary conditions would allow an earlier warning of problems that could affect 

the Missouri. 

A second aid might be the addition of a Missouri River stage measurement device 

or devices so an ice jam in the headwaters of the Oahe stretch of the river could 

be more quickly detected. Lowland flood warnings could be given on a more accurate 

and timely basis. Since ice jams are very hard to predict, additional river condition 

monitoring systems may allow officials to issue earlier warnings to residents. 

Another recommendation would involve the preparation and testing of an ice jam 

response plan. The city will be a very willing contributor to the development of this 

plan, but it lacks expertise in ice jam fighting or response to rapid river stage increases caused by flooding associated with ice jams. The assistance of Federal and 

State resources would aid greatly in this planning effort. 

A fourth suggestion would involve a study of the vulnerable areas of south Bismarck and ways in which either a temporary or permanent dike system might aid 

in the prevention of flooding from the Missouri River or Apple Creek. This study 

should focus on a catastrophic ice jam on the Missouri, similar to the spring 2009 

event, and consider the additive effect of a high Apple Creek flow that might not 

be able to discharge into the Missouri. 

A final recommendation recognizes that prevention of a disaster is the fervent desire of everyone who has experienced the pain of loss caused by such an event. 

While this is never entirely possible, it is reasonable to consider actions that will 

eliminate the event or make it less costly. It would be desirable to consider dredging 

the headwaters of Oahe. Chronic bank erosion and resulting siltation in the quiet 

waters of Oahe have caused many sand bars and a winding river channel. This 

makes ice jamming an increasingly frequent phenomenon. 

Thank you once again for the opportunity to discuss the spring 2009 flood event 

in the Bismarck area. The resources you have provided to help us deal with this 

problem and your willingness to assist with further remediation of this threat are 

deeply appreciated. 

Senator DORGAN. Mayor Warford, thank you. And thank you for 

allowing us to use this facility here in Bismarck. I know you spend 

a fair amount of time here. 

The mayor of Mandan, Mr. Tim Helbling, you may proceed. 

STATEMENT OF HON. TIMOTHY A. HELBLING, MAYOR, CITY OF 

MANDAN, NORTH DAKOTA 

Mr. HELBLING. Good evening. Thank you, Senator Dorgan for 

this opportunity to provide testimony on the importance of flooding 

issues in the Mandan/Bismarck area. There continue to be after effects of the spring flooding along the Missouri River. 

The city of Mandan has spent over $100,000 in the past 3 

months on a temporary rock protection of our storm and sanitary 

sewer outfall pipes. The cause appears to be a failure in a rock 

jetty directly north of these outfall pipes. Until this situation is rectified the river current will continue to erode the river bank. 

And we will, in turn, spend thousands more in attempts to stabilize our infrastructure. In discussions with the Corps of Engineers in Omaha it appears funding is very limited for this type of 
12 

project. We are asking for funding assistance as the damage appears to be a result of a failure in the rock jetty caused by the 

flooding and ice jams earlier this spring. 

Flooding along the Missouri River in part was caused by tremendous amounts of water, ice and debris flowing from the Heart 

River. The Lower Heart Water Resource District feels there are 

several levee areas of concern that should be considered for structural concerns versus general maintenance items. We have lost several feet of bank protection and significant stretches of the river 

leaving the levee directly exposed to the water current right at its 

toe. 

Any future washouts will directly impact the levee system in several areas. Up to this point these areas of concern have been categorized by the Corps of Engineers as general maintenance issues. 

If the vulnerable areas continue to be considered to be general 

maintenance items for the Lower Heart Water Resource District to 

contend with the finances of the Lower Heart Water Resource District will not be adequate. 

We have identified areas we feel are structural concerns requiring repairs to protect the city of Mandan’s infrastructure that could 

total $4 to $6 million. Typically the Lower Heart Water Resource 

District can reserve $15,000 to $30,000 per year for general maintenance. At that rate, even with a typical cost share program, a 25 

percent match, our ability to repair the structural concerns cannot 

realistically be done with any reasonable time. 

The value of a developed real estate in the protected areas of 

Mandan can easily be considered some of the highest value real estate in the area. The Memorial Highway, Marina Bay, Borden Harbor, Lakewood Harbor and the entire southside of Mandan from 

Highway 6 east has increased in both development and value since 

the construction of the levees. 

We want to recognize the assistance from the Corps of Engineers 

has provided to date. As there are several projects that are currently underway. That assistance is greatly appreciated. 

However, structural concerns should be considered for grant programs and fast track approvals. Again, these areas of concern have 

been categorized by the Corps of Engineers as general maintenance 

issues. And we respectfully disagree. 

PREPARED STATEMENT

I’d like to thank you for this opportunity to provide input. And 

thank you for all that you have done to help the cities of Mandan 

and Bismarck during the spring flooding. 

[The statement follows:] 

PREPARED STATEMENT OF HON. TIMOTHY A. HELBLING

Thank you for this opportunity to provide testimony on the importance of flooding 

issues in the Bismarck-Mandan areas. 

There continue to be the after effects of the spring flooding along the Missouri 

River. The city of Mandan has spent over $100,000 in the past 3 months on temporary rock protection of our storm and sanitary sewer outfall pipes. The cause appears to be a failure in a rock jetty directly north of these outfall pipes. Until this 

situation is rectified the river current will continue to erode the river bank and we 

in turn will spend thousands more in attempts to stabilize our infrastructure. In 

discussions with the Corps of Engineers in Omaha, it appears funding is very limited for this type of project. 
13 

We are asking for funding assistance as the damage appears to be the result of 

a failure in the rock jetty caused by the flooding and ice jams this spring. 

Flooding along the Missouri River in part was caused by the tremendous amount 

of water, ice and debris flowing from the Heart River. The Lower Heart Water Resource District (LHWRD) feels there are several levee areas of concern that should 

be considered for ‘‘structural concerns’’ versus general maintenance items. We have 

lost several feet of bank protection in significant stretches of the river leaving the 

levee directly exposed to the water current at its toe. Any future washouts will directly impact the levee system in several areas. Up to this point, these areas of concern have been categorized by the Corps of Engineers as ‘‘general maintenance’’ 

issues. 

If the vulnerable areas continue to be considered ‘‘general maintenance’’ items for 

LHWRD to contend with, the finances of LHWRD will not be adequate. We have 

identified areas we feel are ‘‘structural concerns’’ requiring repairs to protect the 

city of Mandan’s infrastructure that could total $4 to $6 million. Typically the 

LHWRD can reserve $15,000–$30,000 per year for general maintenance. At that 

rate, even with the typical cost share program (25 percent match) our ability to repair these ‘‘structural concerns’’ cannot realistically be done in any reasonable time. 

The value of the developed real estate in the protected areas of Mandan can easily 

be considered some of the highest value real estate in the area. The Memorial Highway, Marina Bay, Borden Harbor, Lakewood Harbor and the entire south side of 

Mandan from Highway 6 east has increased in both development and value since 

the construction of the levees. 

We want to recognize the assistance the Corps of Engineers has provided to date, 

as there are several projects that are currently underway. That assistance is greatly 

appreciated. 

However, structural concerns should be considered for grant programs and fast 

track approvals. Again, these areas of concern have been categorized by the Corps 

of Engineers as ‘‘general maintenance’’ issues and we respectfully disagree. 

The city of Mandan provides treated water to Missouri West Water Systems for 

its rural customers and we also share our water intake structure with Tesoro Refinery. Our intake structure rests along the bank of the Missouri River. During the 

period in which water was not being released from Garrison Dam, we kept around 

the clock watch to ensure we had adequate flow into our intake. At one point we 

were hours away from having no water. The Corps of Engineers and North Dakota 

Department of Emergency Services worked quickly and decisively in allowing a controlled release from Garrison Dam to ensure our intake would continue to function. 

This situation could easily present itself again, not only to the citizens of Mandan, 

its rural residents, Tesoro Refinery the other communities and power plants that 

rely upon water in the Missouri River for their livelihood. Horizontal collector wells, 

that are now being installed as part of the Bismarck water treatment plant, have 

been explored in Mandan, however, the geology does not support this alternative. 

We believe a comprehensive review of available options should be done if releases 

from Garrison Dam are significantly reduced or cut off completely. 

Thank you for the opportunity to provide input. 

Senator DORGAN. Well, Mayor, thank you very much. And now 

we will hear from Mr. Ken Royse, the chairman of the Missouri 

River Joint Water Resource Board. Mr. Royse. 

STATEMENT OF KEN ROYSE, CHAIRMAN, MISSOURI RIVER JOINT 

WATER RESOURCE BOARD 

Mr. ROYSE. Senator Dorgan, thank you for this opportunity to 

provide testimony regarding the issue of flooding in the Bismarck/ 

Mandan area was caused or contributed to by the Missouri River. 

My name is Ken Royse. I’m a resident of Bismarck, North Dakota. And I currently serve as chairman of the Missouri River Joint 

Water Resource Board. The Missouri River Joint Water Resource 

Board is a legally organized joint water board authorized under the 

statute of the State of North Dakota. Our membership are those 

individual county water boards which border either Lake 

Sakakawea, Lake Oahe or the Missouri River. 

Before I offer my testimony I would like to offer sincere thanks 

to you for arranging this hearing and elevating this issue to this 
14 

level of discussion. We understand that this hearing allows us to 

formally place our concerns into a Congressional Record and provide a possible means for improvements and changes to be implemented in the river and reservoir management methods. 

I am confident that the panel that you have assembled today will 

provide you very specific discussions on the issues of flooding which 

Mandan and Bismarck faced this past spring. However my testimony to you will be in broader terms of how several selected Federal programs are affecting the use of the Missouri River system 

in our State. And how those selected programs relate particularly 

to the issue of flooding in the Bismarck/Mandan area. 

The Federal programs I would like to address, each of which 

have a relationship to the flooding issues we’re discussing here 

today, are No. 1 the work and efforts as authorized and conducted 

under title VII of the Missouri River Protection and Implementation Act of 2000. 

No. 2, the Corps managed program commonly referred to as the 

Emergent Sandbar Habitat Program, which is a program implemented due to the Missouri River biological opinion for recovery. 

And No. 3, the recently passed and pending effort referred to as 

a MRAPS process which is a Missouri River Authorized Purposes 

Study as authorized under section 108 of the Omnibus Appropriations Act of 2009. 

The common thread of all these programs relates to the elements 

of sediment siltation and bank and land erosion. All these elements 

had a direct impact on the flooding which occurred in March 2009. 

Relative to the title VII program as you are aware this program 

has provided for a comprehensive study to be conducted for the 

Missouri River system for the State of North Dakota to identify 

issues and effects of sedimentation and siltation. 

The study was recently completed under the direction of the 

Omaha Division of the Corps of Engineers. In this study an attempt was made to quantify the effects siltation has had and is 

having on the issues of economics, recreation, hydropower production, fish and wildlife resources, flood control and Indian and nonIndian historical and cultural sites. In the section of the report 

under flood control the following discussion is provided. 

‘‘Flood control issues within the Missouri River for the Bismarck, North Dakota 

area are caused or affected by one, open water seasonal flooding from Garrison Dam 

operations. 

‘‘Two, open water seasonal flooding from tributaries and other residue drainage 

areas below Garrison Dam combining with releases from Garrison Dam. 

‘‘Three, flooding resulting from ice jams and ice conditions. 

‘‘And four, flooding caused by aggradation in the upper reaches of Lake Oahe.’’ 

And additionally it says, ‘‘Siltation in the reach between Garrison 

Dam and Lake Oahe has resulted in increased risk of flooding in 

the downstream reach between the Dam and the headwater of 

Lake Oahe. Because of this sediment aggradation the impact of ice 

dams on seasonal flooding has increased and is expected to increase.’’ 

Relative to the Emergent Sandbar Habitat Program, I think it 

first important to inform you that the Missouri River Joint Board 

has placed itself on the record of opposing this program. We opposed it based on the intent to the program to place or maintain 

sediment deposits and sandbars within the river system. The North 
15 

Dakota Water Users and the North Dakota Water Resource Association have also adopted similar resolutions in opposition to this 

program. 

While we oppose creating or enhancing sandbars for bird habitat, 

we do recognize the importance of achieving ecological balance in 

the river and reservoir system. Water managers and folks that use 

and enjoy our river system are not anti-environmental. We simply 

believe that a balance of all needs, including a need for adequate 

river management for flood protection needs to be on equal footing 

as fish and wildlife and environmental needs. 

Our opposition is based primarily on the damages that siltation 

and sedimentation can do to the various uses of the river. 

Silt and sediment provide obvious disadvantages to the river use 

in terms of excess in the channel for water and irrigation supply 

and in terms of lessening the life of the empowerment structures. 

And in terms of decreasing power generation ability. 

And in terms of limiting and disrupting an accessible river system for recreation. 

Sedimentation can and does contribute to flooding conditions as 

we have seen this past year where a large sand bar or sand bars 

acted as a restriction to the ice movement and flow from the Heart 

River into the Missouri River. It was that backed up and blocked 

ice which created the conditions by which the flooding of South Bismarck and South and East Mandan occurred. 

Relative to the Missouri River authorized purposes study we believe this effort can and should provide a means for our area to influence a river management system which will further secure flood 

protection for our area. This is an effort, as you are aware, which 

is now in its infancy. The first scoping meeting was held on this 

issue in early October in Pierre, South Dakota. 

At that meeting I would estimate that approximately 150 people 

attended. Of which, perhaps, up to one-third to one-half were from 

downstream States. Even though the Corps had conducted a 

scoping meeting in Kansas City supposedly for the benefit of those 

users and stakeholders of the downstream States, these downstream stakeholders apparently felt the need to attend the Pierre, 

South Dakota meeting, an apparent demonstration of the importance of this issue to them. 

PREPARED STATEMENT

I think the MRAPS program allows all the States a platform and 

structure to revisit a long outdated plan of management and benefit allocation of the Missouri River system. It should be viewed as 

a means where all parties upstream and downstream interest included, can have an opportunity to have objective discussion on the 

best basin wide use of that system. And it should be a means by 

which the issue of the Missouri River and reservoir system management and operations can be modified to address flooding issues 

in the Bismarck/Mandan area. 

Senator, thank you for holding this hearing and accepting this 

testimony, if you have any questions I would be happy to answer 

them. 

[The statement follows:] 
16 

PREPARED STATEMENT OF KEN ROYSE

Dear Senator Dorgan and subcommittee, thank you for this opportunity to provide 

testimony regarding the issue of flooding in the Bismarck and Mandan, North Dakota area as caused or contributed to by the Missouri River. 

My name is Ken Royse. I am a resident of Bismarck, North Dakota and I currently serve as chairman of the Missouri River Joint Water Resource Board. The 

MRJWRB is a legally organized joint water board authorized under the statutes of 

the State of North Dakota; our membership are those individual county water 

boards which border either Lake Sakakawea, Lake Oahe, and/or the Missouri River. 

Before I offer my testimony I would like to offer sincere thanks to you for arranging this hearing and elevating this issue to this level of discussion. We understand 

that this hearing allows us to formally place our concerns into a Congressional 

Record and provides a possible means for improvements and changes to be implemented in the river and reservoir management methods. 

I am confident that the panel you have assembled today will provide you with a 

very specific discussion on the issues of flooding which Bismarck and Mandan faced 

this past spring. However my testimony to you will be in broader terms of how several selected Federal programs are affecting the use of the Missouri River system 

in our State and how those selected programs relate particularly to the issue of 

flooding in the Bismarck and Mandan area. 

The Federal programs I would like to address, each which have a relationship to 

the flooding issues we are discussing here today, are (1) the work and efforts as authorized and conducted under title VII of the Missouri River Protection and Improvement Act of 2000, (2) the Corps managed program commonly referred to as the 

Emergent Sandbar Habitat Program, which is a program implemented due to the 

Missouri River Biological Opinion for Recovery, and (3) the recently passed and 

pending effort referred to as the MRAPS process, which is the Missouri River Authorized Purposes Study, as authorized under section 108 of the Omnibus Appropriations Act of 2009. The common thread of all these programs relates to the elements of sediment, siltation, and bank and land erosion. All these elements had a 

direct impact on the flooding which occurred in March 2009. 

Relative to the Title VII Program.—As you are aware this program has provided 

for a comprehensive study to be conducted for the Missouri River system of the 

State of North Dakota to identify issues and effects of sedimentation and siltation. 

This study was recently completed under the direction of the Omaha Division of the 

Corps of Engineers. In this study an attempt was made to quantify the effects siltation has had and is having on issues of economics, recreation, hydropower production, fish and wildlife resources, flood control and Indian and non-Indian historical 

and cultural sites. In the section of the report under Flood Control the following discussion is provided: 

‘‘Flood control issues within the Missouri River for the Bismarck, North Dakota 

area are caused or affected by (1) open-water seasonal flooding from Garrison Dam 

operations, (2) open-water seasonal flooding from tributaries, and other residual 

drainage areas below Garrison Dam, combining with releases from Garrison Dam, 

(3) flooding, resulting from ice jams and ice conditions, and (4) flooding.’’ 

And additionally, 

‘‘Siltation in the reach between Garrison Dam and Lake Oahe has resulted in increased risk of flooding in the downstream reach between the dam and the headwater of Lake Oahe. Because of this sediment aggradation, the impact of ice dams 

on seasonal flooding has increased and is expected to increase.’’ 

Reference Page 14, Impacts of Siltation of the Missouri River in the State of 

North Dakota, Summary Report, U.S. Army Corps of Engineers, June 2009. 

Relative to the Emergent Sandbar Habitat Program.—I think it first important to 

inform you that the MRJWB has placed itself on the record of opposing this program; we oppose it based on the intent of the program to place or maintain sediment deposits and sandbars within the river system. The North Dakota Water 

Users and the North Dakota Water Resource Association have also adopted similar 

resolutions in opposition to this program. 

While we oppose creating or enhancing sandbars for bird habitat, we do recognize 

the importance of achieving ecological balance in the river and reservoir system. 

Water managers and the folks that use and enjoy our river system are not anti-environmental; we simply believe that a balance of all needs, including the need for adequate river management for flood protection needs to be on equal footing as fish and 

wildlife and environmental needs. 
17 

Our opposition is based primarily on the damages that siltation and sedimentation can do to the various uses of the river. Silt and sediment provide obvious disadvantages to the river use in terms of accessing the channel for water and irrigation supply, and in terms of lessening the life of the impoundment structures, and 

in terms of decreasing power generating ability and in terms of limiting and disrupting an accessible river system for recreation. Sedimentation can and does contribute to flooding conditions as we have seen this past year, where a large sandbar 

or sandbars acted as a restriction to the ice movement and flow from the Heart 

River into the Missouri River. It was that backed up and blocked ice which created 

the conditions by which the flooding of south Bismarck and south and east Mandan 

occurred. 

Relative to the Missouri River Authorized Purposes Study.—We believe this effort 

can and should provide a means for our area to influence a river management system which will further secure flood protection for our area. This is an effort which, 

as you are aware, is now in its infancy. The first area scoping meeting was held 

on this issue in early October in Pierre, South Dakota. At that meeting I would estimate that approximately 150 people attended, of which perhaps up to one-third to 

one-half, were from downstream States. Even though the Corps of Engineers had 

conducted a scoping meeting in Kansas City, supposedly for the benefit of the users 

and stakeholders of the downstream States, those downstream stakeholders apparently felt a need to attend the Pierre, South Dakota meeting in an apparent demonstration of the importance of this issue to them. 

I think the MRAPS program allows all the States a platform and structure to revisit a long outdated plan of management and benefit allocation of the Missouri 

River system. It should be viewed as a means where all parties, upstream and 

downstream interests included, can have the opportunity to have objective discussion on the best basin wide use of that system. 

And it should be a means by which the issue of Missouri River and Reservoir system Management and Operations can be modified to address flooding issues in the 

Bismarck and Mandan areas. 

Senator and subcommittee, thank you for hearing and accepting this testimony. 

If you have any questions I would be happy to answer them. 

Senator DORGAN. Mr. Royse, thank you very much. Let me observe as well the meeting that was held in Pierre, South Dakota 

came following a meeting that had been held in Kansas City, Missouri. In as much as the sponsor of this study and the person that 

wrote the legislation is from North Dakota, it will be advisable at 

some moment for the Corps of Engineers to decide to hold a hearing here in North Dakota. I expect that would happen. 

Let me next call on Mr. Mike Gunsch, the Houston Engineering 

witness today from Bismarck, North Dakota. We appreciate very 

much your being here, Mr. Gunsch. You may proceed. 

STATEMENT OF MICHAEL GUNSCH, DISTRICT ENGINEER, BURLEIGH 

COUNTY WATER RESOURCE DISTRICT 

Mr. GUNSCH. Thank you, Senator for the opportunity to provide 

testimony today regarding the flooding concerns in the Bismarck/ 

Mandan area. I’m currently the District Engineer for the Burleigh 

County Water Resource District, also an Engineering Consultant 

for the Morton County Water Resource District. My remarks today 

are twofold. 

One, I’ve got a separate set relative to the Fox Island issue which 

is strictly the Burleigh County Water Resource District. 

But first I want to start with a joint statement for the Burleigh 

County Water Resource Board, the Morton County Water Resource 

Board and the Lower Heart Board. And it will be primarily technical in nature. In July 2009, Houston was retained by those three 

boards to take a look at the flood issues and the alternatives associated with what’s happening with the flood issues on the Missouri 

River. 
18 

Senator DORGAN. Just so that I understand you. You’re employed 

by Houston Engineering, but testifying on behalf of these boards? 

Mr. GUNSCH. Correct. 

Senator DORGAN. Thank you. 

Mr. GUNSCH. Yes. 

The cost for the effort in reviewing the alternative of the flood 

mitigation issues is underwritten in part through a cost share 

grant for the North Dakota State Water—or North Dakota State 

Engineers, excuse me. The primary focus of that effort that we’re 

looking at for those boards is to define pre-disaster mitigation alternatives that can be implemented to reduce the existing and projected flood risks for Burleigh and Morton County. After evaluating 

the March 2009 ice jam flood event and reviewing prior studies the 

following objectives were developed for further consideration. 

One was a sediment debris removal from within the upper 

reaches of the Oahe delta formation below the Heart River confluence to mitigate the impacts and risks associated with ice jam 

flood events and future sediment deposition. 

Two, evaluate the status of potential aggradation and ongoing 

changes in the stream channel conveyance downstream from Bismarck/Mandan and its impact on the risks associated with the ice 

jam and open water flood elevations. 

Three is evaluate the feasibility of alternatives to lower the current base flood elevations through Burleigh and Morton Counties 

to those documented in the 1995 flood insurance study. And there’s 

a particular focus area. The alternatives for these shall include, but 

not limited to, dredging, channel improvements, reservoir operations, structural measures or a combination thereof. 

Four is define existing and future land uses within and proposed 

bank stabilization measures along the Missouri River correctional 

facility’s property as necessary to achieve the first three objectives. 

There is a nexus between project construction or dredging within 

and along the river and the need for access for potential use of adjacent properties for the placement of dredged materials. So that’s 

why that’s included. 

Five is to complete an assessment to determine the potential economic flood damages or impacts associated with future increases in 

the Missouri River base flood elevations and flood risks in Burleigh 

and Morton County. This effort to include a GIS based analysis of 

existing and potential flood impacts. 

The tax and potential costs associated with these objectives will 

include State, Federal and local issues, but are still under development. So we do not have a number on those at this time. 

Kind of a history, concerns regarding the Oahe delta have been 

around for many years. The 2009 event was just an eye opener. I 

mean, it raised significant awareness that that issue was there. 

There have been ice jams in the past. And there will be ice jams 

in the future. 

In 1985 the Corps of Engineers studied this particular situation 

in a report entitled, Oahe Bismarck Area Studies, Analysis of Missouri River Flood Potential in Bismarck, North Dakota. They evaluated numerous alternatives in which to mitigate the flood impacts. And we are providing a copy of that report for the record for 

your use and reference. 
19 

[The information follows:] 

U.S. ARMY CORPS OF ENGINEERS OMAHA DISTRICT—OAHE-BISMARCK AREA STUDIES

ANALYSIS OF MISSOURI RIVER FLOOD POTENTIAL IN THE BISMARCK, NORTH DAKOTA

AREA, AUGUST 1985

DEPARTMENT OF THE ARMY, 

OMAHA DISTRICT CORPS OF ENGINEERS, 

Omaha, Nebraska, August 7, 1985. 

To All Interested Parties: The Omaha District, Corps of Engineers has completed 

its study of the residual Missouri River flood potential at Bismarck, North Dakota, 

and the alternative measures for alleviating the problem. The study conclusions 

were presented at a meeting of the Coordinating Committee of the BismarckMandan Missouri River Improvement Association on May 23, 1985. Two documents—an information paper and a more detailed technical summary—have been 

prepared on the study and its conclusions. 

The information paper, which is enclosed, is entitled ‘‘Analysis of Missouri River 

Flood Potential in the Bismarck, North Dakota, Area.’’ Its purpose is to provide the 

general public with a summary of the flood potential and an evaluation of the alternative measures for alleviating this flood potential. 

Additional copies of the information paper are available at the Corps’ Bismarck 

office in room 342 of the Federal Building at 3rd and Broadway. Or, a copy will be 

mailed to anyone requesting it by calling the Corps’ Bismarck office at 255–4011, 

Extension 612. 

The North Dakota State Water Commission has been furnished copies of the technical summary and the information paper. The Commission will be conducting a detailed technical review of this material; the review is to be completed by November 

15, 1985. 

A public information meeting will be held in Bismarck after the State Water Commission has completed its review. The purpose of the meeting will be to answer any 

further questions you may have on the study. I have invited the State Water Commission to participate in the meeting to help answer questions. A public notice of 

the meeting will be sent to those receiving this notice and to anyone who contacts 

the Corps’ Bismarck office and asks to be added to the current mailing list. 

Comments on the information paper may also be sent to me at the Omaha District, Corps of Engineers, ATTN: MROPD–P, 215 N. 17th Street, Omaha, Nebraska 

68102–4910. The comment period will remain open until December 15, 1985. 

Following the Commission’s review of the material, the public information meeting, and receipt of all public comments, will consider all views and comments and 

make my final recommendations. 

ROGER B. WHITNEY, 

Lieutenant Colonel, Corps of Engineers, Acting District Engineer. 

SUMMARY

A residual flood potential exists for the south Bismarck area along the Missouri 

River upstream from the Lake Oahe project. Based on a damage analysis of existing 

and projected future development, potential flood damages could average about 

$900,000 per year. Also, during future years, discharges from the upstream Garrison Reservoir will need to be gradually reduced from the current 20,000 c.f.s. during 

the winter ice-in period at Bismarck to reduce the possibility that stages do not increase above the current target ice-in stage. This constraint on winter hydropower 

generation at Garrison Dam is projected to increase the cost of providing power to 

the upper Midwest region by about $500,000 per year. 

Eight alternatives for reducing the potential flood damages and hydropower constraints were evaluated. Most were not economically feasible; therefore, they could 

not be considered for implementation by the Corps of Engineers. The Corps will, 

therefore, continue to reduce releases from Garrison Reservoir at critical high discharge periods at Bismarck—when flows from tributaries downstream from Garrison Dam could cause flooding at Bismarck and during winter ice-in. The criteria for 

ice-in, therefore, will be to continue to target ice-in at 13 feet at the Bismarck gage. 

The city of Bismarck, Burleigh County, and those developing in the flood plain 

should also consider additional flood plain management measures in the form of 

raising new development more than the required 1 foot above the potential existingconditions 100-year flood elevation and raising access roads to areas of extensive development. These flood plain management measures would reduce future flood damages and provide greater safety to persons living in the flood plain. Also, those per-
20 

sons living or having businesses in the flood plain should continue to take advantage of the Federal Flood Insurance Program to minimize flood damage losses. 

INTRODUCTION

Since the construction of the Missouri River main stem dams, flooding at Bismarck, North Dakota, has been limited to low-lying lands adjacent to the Missouri 

River. The last major flood, the flood of record, occurred at Bismarck in 1952—1 

year before closure of Garrison Dam, which is located 75 miles upstream. Even 

though the main stem system has dramatically reduced flooding in the Bismarck 

area, a residual flood potential still exists because of runoff from the uncontrolled 

Missouri River drainage area between Garrison Dam and Bismarck, the influence 

of sediment deposition in and upstream from Lake Oahe, and ice affected river 

stages. 

The Corps of Engineers has evaluated the potential for residual flooding since 

1954, when lands were first delineated for inclusion in the downstream Lake Oahe 

project. At that tine, it was projected that lands as far upstream as the Bismarck 

Memorial Bridge (1960 river mile 1314.2) could be influenced by the deposition of 

sediments in the Missouri River channel. Development in the low-lying lands adjacent to the river at Bismarck has increased the potential for flood damages if a flood 

were to occur. Since construction of the Garrison project, the Corps of Engineers has 

limited discharges from the Garrison Reservoir during critical periods to minimize 

flooding of these low-lying lands and to minimize damages to the development. 

This information paper summarizes (1) the flood potential at Bismarck before the 

construction of the main stem system, (2) the flood potential as it currently exists, 

and (3) the projected future flood potential. It also summarizes the technical evaluation of eight alternatives that would reduce the flood potential, and it presents a 

summary of the feasibility of these various alternatives. 

SUMMARY OF THE FLOOD POTENTIAL

Before Construction of Main Stem Dams 

Prior to the construction of the main stem dams, flood plain areas on both sides 

of the Missouri River south of Bismarck were frequently flooded to significant 

depths. Records dating back to 1881 indicate that major flooding occurred on an average of once every 6 or 7 years; however, no significant urban flood damages occurred before the 1939 flood. Because of the recurrent flooding, the south Bismarck 

area was generally unsuitable for urban development. Beginning in the 1930s, however, some people were willing to take the risk, and Bismarck extended into the 

Missouri River flood plain at some points. 

Fort Peck Dam in Montana was the first of six dams to be constructed on the 

main stem of the Missouri River. Fort Peck Dam began to impound water in 1937, 

and the project became fully operational for flood control in 1940. Because it controlled 31 percent of the Missouri River basin drainage area upstream from Bismarck, it reduced the frequent flood threat at Bismarck to some degree. However, 

the flood threat was not eliminated; the 1952 flood of record at Bismarck demonstrated the continued existence of the likelihood of significant flood events in the 

area. The maximum stage at the Bismarck gage (1960 river mile 1314.6) reached 

27.9 feet, with an estimated discharge of 500,000 cubic feet per second (c.f.s.). Based 

on a gage datum of zero equalling 1618.4 feet mean sea level (m.s.l.) (became 1618.3 

feet m.s.l. in 1979), the flood reached an elevation of 1646.3 feet m.s.l. at the gage. 

The entire south Bismarck area was under up to 20 feet of water. 

Table 1 presents estimated discharges for a range of flood events—from the 5-year 

up through the 500-year—at the Bismarck gage for the period prior to the construction of Garrison Dam. Only limited gage discharge data are available for the preFort Peck Dam period; therefore, the values presented in table 1 are based on a limited period prior to 1953, when Garrison Dam began impounding water. As shown 

in table 1, pre-system discharges approaching 1 million c.f.s. could have occurred at 

Bismarck. It should also be noted that the 1952 flood of record was less than a 100- 

year flood event. Even though it is a very remote flood event, the 500-year flood was 

included in table 1 because such events have occurred at other locations within the 

Missouri River basin and the 500-year flood is commonly the basis for the design 

of flood control projects in urban areas. 

Table 1 also includes the estimated flood stages and the corresponding flood elevations for the 5- through 500-year events. These stages are based on the presystem 

all-seasons stage-frequency curve for the Bismarck gage, which is a probabilistic 

combination of stages for the complete range of open-water (spring, summer, and 

fall) and ice-affected (winter) events. 
21 

TABLE 1.—PRESYSTEM FLOODING POTENTIAL AT THE BISMARCK GAGE 

Recurrence Internal (years) Discharge (c.f.s.) Stage (feet) Flood Elevation 

(feet m.s.l.) 

5 ................................................................................................................. 180,000 21.6 1640.0 

10 ............................................................................................................... 250,000 24.2 1642.6 

25 ............................................................................................................... 360,000 26.3 1644.7 

50 ............................................................................................................... 460,000 28.7 1647.1 

100 ............................................................................................................. 583,000 30.3 1648.7 

500 ............................................................................................................. 990,000 33.5 1651.9 

To place the presystem flooding in perspective, potential flood depths at the Kirkwood Shopping Center, located south of the downtown area, were estimated. Although the parking lot varies in elevation, it averages 1636 feet m.s.l. Floodwaters 

from a 10-year event would have been about 6.5 feet deep; 50-year flood waters 

would have been over 11 feet deep, and 100-year flood waters would have been almost 13 feet deep. Table 2 presents pre-system flood elevations for the 5-, 10-, 

50-, and 100-year floods at five locations along the river in the Bismarck area. These 

elevations are based on historical stage data for the Bismarck gage that were obtained prior to the construction of Garrison Dam. Based on the range of ground elevations near these locations, flood depths of from 11 to 20 feet could have occurred 

along the river with the 100-year flood. A 50-year flood would have ranged from 9 

to 17 feet in depth, and a 10-year flood would have had depths generally from 5 

to 14 feet. 

TABLE 2.—POTENTIAL PRESYSTEM FLOOD ELEVATIONS IN THE BISMARCK AREA 

Location 1960 River Mile 

Flood Elevations (feet m.s.l.) 

5-year 10-year 50-year 100-year 

Square Butte Creek ......................... 1,322.5 1,645.0 1,647.3 1,651.9 1,653.5 

Bismarck Gage ................................ 1,314.6 1,640.0 1,642.6 1,647.1 1,648.7 

Heart River ....................................... 1,311.0 1,637.5 1,640.2 1,644.7 1,646.3 

General Sibley Park ......................... 1,307.0 1,635.0 1,637.5 1,641.9 1,643.5 

Cabe Project Boundary .................... 1,303.0 1,632.5 1,634.8 1,639.4 1,641.0 

EXISTING CONDITIONS

The potential for significant flooding at Bismarck was reduced in 1953 when Missouri River flows were first controlled by Garrison Dam, which is located about 75 

river miles upstream. Estimated flood discharges at the Bismarck gage for a range 

of events under existing conditions are presented in table 3. A comparison of these 

discharges with the presystem discharges shows that Garrison Dam has provided 

a significant reduction in Bismarck flood discharges—a reduction of from 71 to 85 

percent. 

TABLE 3.—EXISTING-CONDITIONS MISSOURI RIVER DISCHARGES AT THE BISMARCK GAGE 

Recurrence Interval (years) Discharge (c.f.s.) 

Reduction in Dis- charge 1

(percent) 

5 .............................................................................................................................................. 52,000 71 

10 ............................................................................................................................................ 57,000 77 

25 ............................................................................................................................................ 71,500 80 

50 ............................................................................................................................................ 81,500 82 

100 .......................................................................................................................................... 94,000 83 

500 .......................................................................................................................................... 148,000 85 

1 As compared to the presystem discharges presented in table 1. 

Even with the dramatic reduction in discharges, residual Missouri River flooding 

could still be a problem at Bismarck because of increased occupation of the 100-year 

flood plain. Minor lowland flooding has occurred on a few occasions since the closure 

of Garrison Dam in 1953. The greatest amount of flooding occurred in the summer 

of 1975, when heavy spring rains in Montana caused high discharges from Garrison 

Reservoir. Although stages reached 14.2 feet at the Bismarck gage (discharge 

equaled 68,900 c.f.s.), this flooding inundated only the low-lying lands along the 
22 

river. No significant economic damages occurred in the south Bismarck area as a 

result of that event. A recurrence of that flood event today could cause some damage 

because many additional homes have been constructed in the area. Similar flooding 

also occurred in January 1983 as the result of an ice jam in the vicinity of the Heart 

River. These flood events showed that some flooding can still occur in the south Bismarck area, although not of the magnitude of those that occurred before construction of the main stem system of dams. 

Based on cross-sectional data obtained in 1981 and 1982, potential flood depths 

have been determined for existing conditions. (The term ‘‘existing conditions’’ describes the conditions which could occur only if the assumptions underlying the hydrologic analysis in fact occur.) Table 4 presents the potential existing-conditions allseasons flood elevations for the 5-, 10-, 50-, and 100-year floods in the Bismarck 

area. Flooding from major events would occur most often in the spring and summer 

because of the large flows from the Knife River and Heart River basins—the two 

major tributaries between Garrison Dam and Lake Oahe. Because the effects of discharges from the Heart River are somewhat greater than those from the Knife River 

and because the mouth of the Heart River is at Bismarck, the Heart River has a 

greater effect on the peak discharges and stages at Bismarck than the Knife River. 

Even though the upstream half of the Heart River basin is controlled by Heart 

Butte Dam, runoff from the lower, uncontrolled half of the basin would reach Bismarck in 11⁄2 to 2 days, the same amount of time it takes for Garrison Reservoir 

releases to reach Bismarck. It, therefore, would be impossible to cut releases from 

Garrison Reservoir in time to reduce the coincident peak at Bismarck. The flood elevations presented in table 4 represent those that would result from high flows from 

the Knife River and Heart River basins coincident with Garrison Reservoir releases. 

The Corps, however, will continue to reduce Garrison releases to limit flooding at 

Bismarck at times of increased flood potential because, under certain circumstances, 

flooding could be reduced when the high discharges are primarily from the Knife 

River and some minor tributaries upstream from Bismarck. Table 5 shows how 

much lower existing-conditions stages are than those presented in table 2 for the 

presystem flooding conditions. Briefly, the potential existing-conditions flooding in 

the south Bismarck area would be is from about 7 feet lower for the 5-year event 

to about 13 feet lower for the 100-year event. 

TABLE 4.—POTENTIAL EXISTING-CONDITIONS ALL-SEASONS FLOOD ELEVATIONS IN THE BISMARCK 

AREA 

Location 1960 River Mile 

Flood Elevations (feet m.s.l.) 

5-year 10-year 50-year 100-year 

Square Butte Creek ......................... 1,322.5 1,637.8 1,638.0 1,638.9 1,640.0 

Bismarck Gage ................................ 1,314.6 1,632.7 1,633.3 1,634.5 1,635.7 

Heart River ....................................... 1,311.0 1,630.4 1,631.2 1,632.7 1,633.9 

General Sibley Park ......................... 1,307.0 1,628.0 1,629.0 1,630.5 1,631.7 

Oahe Project Boundary .................... 1,303.0 1,625.6 1,626.5 1,628.0 1,629.2 

TABLE 5.—REDUCTION IN POTENTIAL FLOOD ELEVATIONS FROM PRESYSTEM TO EXISTING 

CONDITIONS 

Location 1960 River Mile 

Flood Elevation Reduction (feet) 

5-year 10-year 50-year 100-year 

Square Butte Creek ......................... 1,322.5 7.2 9.3 13.0 13.5 

Bismarck Gage ................................ 1,314.6 7.3 9.3 12.6 13.0 

Heart River ....................................... 1,311.0 7.1 9.0 12.0 12.4 

General Sibley Park ......................... 1,307.0 7.0 8.5 11.4 11.8 

Oahe Project Boundary .................... 1,303.0 6.9 8.3 11.4 11.8 

The reduced flooding since closure of Garrison Dam in 1953 encouraged considerable residential development to take place in the south Bismarck area—most of it 

occurring on the Bismarck side of the river—even though this area has been designated as the 100-year flood plain by the Federal Emergency Management Agency 

(FEMA). About 220 homes are now located in the south Bismarck area. Most of 

these homes—and all of the newer homes—were constructed with their first floor 

elevations at least 1 foot above the existing-conditions 100-year flood, as required 

by FEMA for flood insurance purposes. They would, therefore, be significantly af-
23 

fected by only the very exceptional flood events such as the existing-conditions 100- 

year flood, which could cause floodwaters about 5 feet deep in some residential 

areas. 

The potential for economic flood damages was analyzed in December 1984. Using 

land use data obtained in 1980 and 1984 and the flood depths from the existingconditions hydraulic analysis, potential flood damages for various flood events and, 

subsequently, the potential annual damages were estimated. The estimated potential existing-conditions flood damages in the south Bismarck area for the 5-, 10-, 

100-, and 500-year events are presented in table 6. These damages are based on 

damages to structures and contents; no damages were estimated for roads, streets, 

utilities, lands, cleanup, or other categories. Potential annual damages were computed based on a probabilistic analysis. Even though the relatively infrequent 

events between the 100- and 500-year events have a very low likelihood of occurring 

each year, they result in about 75 percent of the existing-conditions potential annual 

damages. The potential annual damages to structures and contents for existing-conditions flooding in the south Bismarck area total about $300,000. This is an average 

figure based on all damages listed in table 6, including the 500-year event. 

TABLE 6.—POTENTIAL EXISTING-CONDITIONS FLOOD DAMAGES 

Recurrence Interval (years) Estimated Flood 

Damages 

5 ........................................................................................................................................................................... $69,000 

10 ......................................................................................................................................................................... 140,000 

50 ......................................................................................................................................................................... 670,000 

100 ....................................................................................................................................................................... 1,800,000 

500 ....................................................................................................................................................................... 47,000,000 

Hydropower releases from Garrison Reservoir are normally reduced to about 

20,000 c.f.s. each December just prior to ice formation through the Bismarck area. 

This reduction in flow is made to ensure that ice-affected stages do not increase to 

the point of flooding lands adjacent to the river at Bismarck. After the initial icein, discharges can be gradually increased to an average daily discharge of about 

33,000 c.f.s.; this gradual increase occurs as the streambed adjusts and the underside of the ice becomes smoother. The short-term release reduction limits the quantity of winter energy which can be produced. Subsequent increased releases provide 

greater freedom in meeting the hydropower needs because the Garrison powerplant 

can be peaked a larger part of the day without exceeding the higher daily average 

release rates. The river reaches downstream from Garrison Dam limit its full hydropower potential; however, the Missouri River main stem system was designed and 

the power is marketed in accordance with all of these conditions, which have been 

maintained throughout the early life of the project. 

FUTURE CONDITIONS

There are two processes occurring that will reduce the capacity of the river in the 

study reach. First, as the sediment-carrying-water moves down the Missouri River 

into Lake Oahe, the flow velocities decrease and the sediment in suspension is deposited along the bottom of the channel, thereby reducing its capacity. Second, the 

river is responding to the new regulated flow regime by adjusting its sandy bed and 

banks to form a generally narrower and deeper channel. This also tends to reduce 

the channel capacity. 

The Missouri River will continue to adjust its cross section in response to the 

above two processes until a quasi-state of equilibrium between the regulated flow 

regime and the river channel has been attained. After this adjustment is completed, 

the channel will remain about the same size in the Bismarck area while the deltabuilding process proceeds farther into the Lake Oahe pool. Fluctuations in channel 

size will occur as the flows and Lake Oahe pool levels vary from year to year. 

A baseline condition for the future operation of the Garrison project had to be 

identified before the potential future-conditions residual flooding elevations could be 

computed for the south Bismarck area. The all-seasons flood elevations for the more 

frequent events are closely related to the ice-in criteria. Currently, ice-in is targeted 

at a 13-foot Bismarck gage stage, and this criteria will be continued. The all-seasons 

flood elevations for the less frequent events are affected by the assumed coincident 

Garrison releases during high downstream tributary inflows to the Missouri River. 

Garrison releases will continue to be reduced during high downstream inflow from 

the tributaries whenever such action would reduce peak flows at Bismarck, and the 
24 

combined Garrison releases and tributary inflows will continue to be the same as 

assumed for the existing-conditions analysis. 

Table 7 presents the flood elevations that are expected to occur once the future 

equilibrium condition is reached. It also presents the increases in flood elevations 

over the existing-conditions flood elevations. As shown, ultimate future flood elevations could be from 0.3 foot to 1.0 foot higher than those that currently could 

occur at locations from the Bismarck gage downstream to the current Lake Oahe 

project boundary. 
25 

TABLE 7.—POTENTIAL FUTURE-CONDITIONS FLOOD ELEVATIONS 

Location 

Flood Elevations (feet m.s.l.) Change from Existing conditions (feet) 

5-year 10-year 50-year 100-year 5-year 10-year 50-year 100-year 

Square Butte Creek ................................................................................. 1,638.0 1,638.2 1,639.4 1,640.6 ∂0.2 ∂0.2 ∂0.5 ∂0.6 Bismarck Gage ........................................................................................ 1,633.1 1,633.9 1,635.9 1,637.0 ∂0.4 ∂0.6 ∂1.4 ∂1.3 Heart River .............................................................................................. 1,630.7 1,631.7 1,633.5 1,634.7 ∂0.3 ∂0.5 ∂0.8 ∂0.8 General Sibley Park ................................................................................. 1,628.3 1,629.4 1,631.3 1,632.5 ∂0.3 ∂0.4 ∂0.8 ∂0.8 Oahe Project Boundary ............................................................................ 1,626.0 1,627.0 1,629.0 1,630.1 ∂0.4 ∂0.5 ∂1.0 ∂0.9 
26 

Table 8 shows the differences between the presystem flood elevations for various 

events and the potential future-conditions flood elevations. Significant reductions in 

stages from those that could have occurred before the main stem dams were constructed have occurred and will continue to occur in the future. The potential 5-year 

flood elevations would be about 6 to 7 feet lower and the potential 100-year flood 

elevations would be about 11 to 13 feet lower than they could have been without 

the construction of the main stem dams. 

TABLE 8.—REDUCTION IN POTENTIAL FLOOD ELEVATIONS FROM PRESYSTEM TO FUTURE 

CONDITIONS 

Location 

Flood Elevation Reductions (feet) 

5-year 10-year 50-year 100-year 

Square Butte Creek ...................................................... 7.0 9.1 12.5 12.9 

Bismarck Gage ............................................................. 6.9 8.7 11.2 11.7 

Heart River .................................................................... 6.8 8.5 11.2 11.6 

General Sibley Park ...................................................... 6.7 8.1 10.6 11.0 

Oahe Project Boundary ................................................. 6.5 7.8 10.4 10.9 

Plate 1 shows the 5-year flood outlines for presystem, existing, and future conditions. Plates 2 and 3 show the same comparison for the 10- and 100-year flood 

events, respectively. 

The flooded areas shown on these plates were developed by determining the flood 

elevation from the water surface profiles for a given area and then locating the limit 

of flooding in that area through the use of 2-foot contour interval topographic mapping. The flood outlines were then transferred from the topographic mapping onto 

aerial photographs; the blue shaded area represents the potential existing-conditions flooded areas. Since most of the homes in the south Bismarck area are built 

on mounds of earth which are elevated above the 100-year flood elevation, these 

homes may only be surrounded by water during a major flood event, with little or 

no damage resulting to the structure itself. (The means of access to many of these, 

however, could be flooded.) Because of the small scale of the aerial photography, it 

was impossible to show the area flooded around each individual residence. Therefore, the flooded areas represent only the outside limit of the flooded area, and they 

do not include small islands within the flooded area. 

Flood elevations shown on a water surface profile under open-water conditions 

normally apply laterally over most of the flood plain width. However, ice along the 

banks of the river will generally act as a barrier to floodwater entering some of the 

overbank areas under ice-affected conditions. Thus, the flooded area corresponding 

to a given ice-affected water surface elevation may not extend landward as far as 

for open-flow conditions. The extent of the area flooded for a given ice-affected stage 

depends to a great extent on how the river ices in. As the river ices in and the head 

of the ice moves through the Bismarck area, the river stages will normally shift upward because of the additional roughness of the ice cover. After the initial ice-in period, the release from Garrison Reservoir can be gradually increased. Because of the 

smoothing of the streambed and the underside of the ice cover, this increase in discharge can normally be made without a corresponding increase in stage in the Bismarck area. Field observations made during past ice-in periods indicate that if the 

river ices in as described above, then the ice which forms along the riverbanks will 

act as a barrier to floodwater entering scene overbank areas. However, it is possible 

for a small ice jam to occur during the ice-in process, and this would result in an 

increase in stage. If this happens, the floodwater would flow into the overbank areas 

in much the same manner as it would for open-flow conditions. The flood of January 

1983 is an example of this type of flood event. This event was the result of an ice 

jam downstream from the Heart River that caused the inundation of much of the 

lower portion of Fox Island. For the purposes of this study, therefore, the flooded 

areas were drawn with the intent of showing the maximum area that could be affected for a given flood event. The flooded areas for the 5- and 10-year events were 

drawn by extending the channel water surface elevation laterally across the flood 

plain. However, it is recognized that, for ice-affected flood events, this assumption 

may not apply. 

A review of table 8 and plates 1 through 3 demonstrates that the main stem dams 

will continue to significantly reduce the amount of flooding from that which could 

have occurred without the construction of the rain stem dams. As aggradation continues in the future, flood stages would be expected to gradually increase above the 

existing-conditions stages; flood damages may also increase. Additional development 
27 

is expected to occur in the south Bismarck area. This development would also result 

in an increase in damages for most storm frequencies and in an increase in potential annual damages. The potential future-conditions flood damages presented in 

table 9 are based on continued development of the south Bismarck area over the 

next 50 years. (Population projections were used as a basis for the rate of development.) The potential annual damages would also increase over the next 100 years. 

Two additional assumptions were made in order to compute the flood damages. The 

future-conditions channel size was assumed to occur in 20 years, and the potential 

annual damages were discounted over the next 100 years. The potential annual 

flood damages were estimated to increase from $300,000 under existing conditions 

to a long-term average of $910,000. 

TABLE 9.—POTENTIAL FUTURE-CONDITIONS FLOOD DAMAGES 

Recurrence Interval Estimated Flood Damages 

5-Year ................................................................................................................................................................... $93,000 

10-year ................................................................................................................................................................. 310,000 

50-year ................................................................................................................................................................. 2,700,000 

100-year ............................................................................................................................................................... 12,200,000 

500-year ............................................................................................................................................................... 129,000,000 

Although current contractual hydropower agreements will continue to be met 

when future discharges are reduced during the winter months, there will be an increase in the regional power system cost. Some of the power that would have been 

generated with the more economical hydropower units at the dam sites has to be 

generated by utilities using more costly generating facilities, such as coal- or oilfired units. The value of this constraint in terms of increased operating costs to the 

region’s utilities is estimated to be about $500,000 per year. This value is in terms 

of 1985 dollars, and it was determined by discounting the increased costs over the 

next 100 years at an 8.375 percent discount rate. The hydropower constraint was 

assumed to increase from zero currently to the full value by the year 2005 (20 

years). There may also be a cost in terms of reduced reliability of the main stem 

hydropower generating capabilities; however, the value of this cost cannot be readily 

determined. 

Table 10 presents an economic summary of the residual flood problem at Bismarck, based on a continuation of the ice-in at a 13-foot stage. Combined potential 

annual flood damages and increased power costs total $1,410,000 per year. The 

magnitude of this annual cost warrants a formulation and evaluation of alternative 

solutions to reduce the impacts of the residual flood problem at Bismarck. 

TABLE 10.—ECONOMIC SUMMARY OF THE POTENTIAL RESIDUAL FLOOD PROBLEM 

Potential Annual Flood Damages: 

Existing Conditions ..................................................................................................................................... $300,000 

Future Conditions (2085) ............................................................................................................................ 1,370,000 

Composite Annual Value ............................................................................................................................. 910,000 

Reduced Hydropower Capacity: 

Average Annual Value ................................................................................................................................. 500,000 

Total ........................................................................................................................................................ 1,410,000 

THE ALTERNATIVES

Eight basic alternatives to the continuation of the current 13-foot ice-in stage criteria—the baseline condition—have been evaluated as measures to reduce the potential residual flood problem in the south Bismarck area and to ensure the continuation of the current level of Garrison hydropower generation in the future. These 

alternatives include (1) channel dredging, (2) channel cutoffs, (3) bank stabilization, 

(4) levees, (5) Garrison operational changes, (6) Oahe operational changes, (7) land 

acquisition, and (8) flood plain management. All of these alternatives do not provide 

a complete solution to the flood potential and the continuation of the current level 

of Garrison hydropower generation. These alternatives were selected jointly by the 

Corps of Engineers and the Bismarck-Mandan Missouri River Improvement Association—a local coordinating committee—primarily because each alternative had possibilities for reducing the residual flooding potential at Bismarck. A detailed evalua-
28 

tion of the alternatives determined that several of them had very limited effectiveness in reducing the residual potential for further floods, the future hydropower constraint, or both. 

The economic evaluation of the alternatives was based on a 100-year project life 

at a discount rate of 8.375 percent. All costs and benefits are in terms of 1985 dollars. As with the computation of flood damages and increased power needs, the existing conditions were assumed to occur in 1985 and the future conditions would 

first occur in the year 2005. 

A brief discussion of each of the alternatives follows. Each discussion includes a 

description of the alternative, its effectiveness in addressing the problems, and the 

costs, benefits, and feasibility of the alternative. 

CHANNEL DREDGING

Dredging the Missouri River between river miles 1315 and 1299—refer to plate 

4—was evaluated because it would provide a larger channel through the south Bismarck area. Options 1 and 2 were designed to convey the 5- and 10-year all-seasons 

flood events, respectively, past the Bismarck gage at a 12-foot stage. The channel 

would be redredged when the stages for these events would exceed 14 feet. Options 

3 and 4 are similar; however, redredging would be conducted when stages for the 

5- and 10-year events reach 13 feet. Implementation of options 1 or 3 would initially 

reduce existing-conditions stages about 2.4 feet, and implementation of options 2 or 

4 would initially reduce the existing-conditions stages 3.0 feet. 

All four options would require frequent redredging to regain the design channel 

capacity. Disposal areas ranging from 220 to 660 acres, for disposal at a 10-foot 

depth, would be required each time redredging is necessary. Table 11 presents information on each of the four dredging options. 

TABLE 11.—PERTINENT DATA—DREDGING 

Item 

Options 

1 2 3 4 

Design Flood ................................................................. 5-year 10-year 5-year 10-year 

Stage Before Dredging (feet) 1 ..................................... 14.4 15.0 14.4 15.0 

Stage after Dredging (feet) 1 ........................................ 12.0 12.0 12.0 12.0 

Maximum Stage Reduction for the 5-year event 2 ....... 2.4 3.0 2.4 3.0 

Stage Before Redredging (feet) 1 3 ............................... 14.4 14.2 13.0 13.0 

Minimum Stage Reduction for the 5-year event 2 ....... ........................ 0.8 1.4 2.0 

Redredging Frequency (years) ...................................... 5 3 1.5 1 

Disposal Areas (acres):4

Initial .................................................................... 1,250 1,400 1,250 1,400 

Redredging ........................................................... 660 530 260 220 

Total 5 ................................................................... 14,500 18,900 18,400 23,400 

1 All-seasons flood stage at Bismarck gage. 

2 As compared to the existing-conditions 5-year, all-seasons flood stage. 

3 Expected river stage for the design flood before redredging. 

4 Disposal area estimates based on 10-foot disposal depth. 

5 Total disposal area for 100-year period of analysis. 

As shown in table 11, a sizeable area would be needed for disposal areas. The disposal of the dredged material would affect more land than would be flooded by a 

relatively large flood, and it would have significant adverse environmental impacts. 

Initially, as shown in table 11, the 5- or 10-year flood stages would be reduced 

by 2.4 or 3.0 feet, respectively, for the four options that were evaluated. However, 

the channel would fill in following each dredging; this would require frequent redredging to restore the dredged channel to its design capacity. The highest stages 

prior to each redredging would be equal to or lower than the existing-conditions 

flood elevations (refer to table 11—minimum stage reduction for the 5-year event). 

The costs for the four dredging options, including land acquisition costs, are presented in table 12. The initial dredging costs exceed $30 million for all four options, 

while the redredging costs range from $5.8 million to $17.2 million. Based on the 

varying redredging intervals presented in table 11, the average annual costs range 

from $6.1 million to $8.6 million. 
29 

TABLE 12.—ECONOMIC SUMMARY—DREDGING 

Item 

Dredging Options 

1 2 3 4 

Costs: 

Initial .................................................................... $32,100,000 $32,900,000 $32,100,000 $32,900,000 

Redredging ........................................................... $17,200,000 $13,400,000 $6,700,000 $5,800,000 

Average Annual .................................................... $6,100,000 $7,200,000 $7,200,000 $8,600,000 

Average Annual Benefits: 

Flood Damage Reduction ..................................... $670,000 $800,000 $800,000 $860,000 

Hydropower ........................................................... $500,000 $500,000 $500,000 $500,000 

Fill Reduction ....................................................... $40,000 $70,000 $70,000 $80,000 

Total ................................................................ $1,210,000 $1,370,000 $1,370,000 $1,440,000 

Net Benefits .................................................................. ¥$4,890,000 ¥$5,830,000 ¥$5,830,000 ¥$7,160,000 

Benefit-Cost Ratio ........................................................ 0.2 0.2 0.2 0.2 

The flood damage reduction and hydropower benefits for dredging the channel are 

included in table 12. Dredging would result in a channel that is as large or larger 

than the existing channel—depending on the option and the length of time between 

dredgings—and always larger than the projected future-conditions channel. The expected reduction in potential annual flood damages would be from $670,000 to 

$860,000 per year. This alternative would reduce the 100-year flood elevations by 

up to 3 feet. The requirement for fill material to elevate structures in the 100-year 

flood would be reduced, thereby reducing building costs by up to $80,000 per year. 

The larger channel would result in no future hydropower constraints; therefore, average annual hydropower benefits of $500,000 would be expected with all four 

dredging options. The total benefits for the dredging alternatives, therefore, range 

from $1,210,000 to $1,440,000 per year. 

Based on the annual costs and benefits. presented in table 12, the benefit-cost 

ratio for each of the dredging options is 0.2. 

CHANNEL CUTOFFS

Channel cutoffs, like channel dredging, would reduce flood stages by providing 

better conveyance of floodflows through the south Bismarck area. Two potential cutoff sites, one located within (upper) and the other downstream (lower) from the 

south Bismarck area, are shown on plate 5. Three options were initially considered. 

Only two of these options were effective in reducing stages—option 1, the upper cutoff, and option 2, both cutoffs; the lower cutoff, option 3, alone would not be effective. Therefore, only options 1 and 2 were evaluated. 

Both cutoffs would require extensive modifications. The upper cutoff would require the excavation of 9,200,000 cubic yards and the lower cutoff would require the 

excavation of 10,300,000 cubic yards. The cutoff channels would be riprapped to protect against erosion, and channel blocks would be required across the existing channel at the upstream ends of the cutoffs. Each cutoff would require about 600 acres 

for disposal of excavated material to a depth of 10 feet. The upper cutoff would 

eliminate access to the remainder of Sibley Island. 

Option 2 would be more effective than option 1. At Fox Island, option 2 would 

initially reduce stages by 2.0 feet for the 5- and the 10-year floods; option 1 would 

initially reduce those stages by 1.5 feet. Over the next 15 to 20 years, both options 

would lose much of their effectiveness. After 15 to 20 years, the upper cutoff would 

result in a net increase above the baseline-conditions stages of 0.1 foot for the future-conditions 5-year event and a net decrease of 0.1 foot for the 10-year event. 

Both cutoffs would result in a net decrease from the baseline conditions stages of 

0.7 and 0.9 foot for the 5- and 10-year future-conditions events, respectively. With 

option 1, the future-conditions flood stages at Fox Island, therefore, would be 0.4 

foot above the existing-conditions stages. Future-conditions flood stages would be 0.4 

foot below the existing-conditions stages with option 2. 

Table 13 presents an economic summary of the channel cutoff options. The first 

cost of option 1 would be $24.1 million, including $600,000 for acquisition of the cutoff and disposal areas. Option 2 would have a first cost of $48.7 million, which also 

includes $600,000 for land acquisition. The lower cutoff area is on existing Lake 

Oahe project lands; acquisition of additional lands would not be required. These 

costs do not include land acquisition for the remainder of Sibley Island, which would 

be inaccessible. The estimated annual costs to maintain the cutoffs is about 1 per-
30 

cent of the first costs of construction, or about $240,000 and $480,000 for options 

1 and 2, respectively. The estimated average annual costs of options 1 and 2 are 

$2,300,000 and $4,600,000, respectively. 

TABLE 13.—ECONOMIC SUMMARY—CHANNEL CUTOFFS 

Item 

Cutoff Options 

1 2 

Costs: 

Construction ................................................................................................................... $24,100,000 $48,700,000 

Operation and Maintenance ........................................................................................... $240,000 $480,000 

Average Annual .............................................................................................................. $2,300,000 $4,600,000 

Average Annual Benefits: 

Flood Damage Reduction ............................................................................................... $400,000 $580,000 

Hydropower ..................................................................................................................... ........................ $500,000 

Fill Reduction ................................................................................................................. ........................ ........................

Total ........................................................................................................................... $400,000 $1,080,000 

Net Benefits ............................................................................................................................ ¥$1,900,000 ¥$3,520,000

Benefit-Cost Ratio ................................................................................................................... 0.2 0.2 

Option 1 would result in flood damage reduction benefits of $400,000 per year. 

Option 2 flood damage reduction benefits would be $580,000 per year. Neither option would result in a significant reduction in fill needs; therefore, there would be 

no fill reduction benefits. 

Construction of only the upstream cutoff would not eliminate any of the future 

expected constraints on hydropower releases at the Garrison project; therefore, option 1 has no hydropower benefits. Option 2, however, would result in a channel capacity at Bismarck equivalent to the existing-conditions capacity, and it would 

eliminate all future hydropower constraints at the Garrison project. The hydropower 

benefits of option 2 would be $500,000 per year. The benefit-cost ratios for the channel cutoff options are both 0.2. 

BANK STABILIZATION

The bank stabilization alternative was evaluated because it would reduce the future aggradation rate and, thereby, delay the occurrence of the higher, future-conditions flood stages. This alternative would consist of providing protection to all bank 

areas within the Garrison dam to Lake Oahe reach that are either actively eroding 

at this time, have experienced erosion in the past, or have a strong potential for 

erosion in the future. Basically, this alternative would result in total stabilization 

of all eroding banklines within the 87-mile reach. The stabilization methods used 

would be similar to those already constructed within this reach. 

Stabilizing the banks would eliminate only one of several sources of sediment to 

the Missouri River upstream from Bismarck. The other sources of sediment provide 

the major portion of the sediment load, and they would continue to cause 

aggradation. The stabilization would not ultimately reduce future water levels below 

those that would occur for the baseline condition. 

The total cost of bank stabilization is estimated to be $24,500,000. Based on experience with existing stabilization measures on the Missouri River, the annual operation and maintenance costs are estimated to be 1 percent of the first cost or approximately $250,000. The average annual costs would, therefore, be $2,300,000. An 

economic summary is presented in table 14. 

Based on delaying the ultimate conditions an additional 10 years, the flood reduction benefits would be $40,000 per year, as shown in table 14. This alternative 

would have no fill reduction benefits. Land losses in the erosion areas could be reduced by as much as 50 acres per year, resulting in an annual benefit of $30,000. 

Also, based on the 10-year delay in reaching the projected channel size, hydropower 

benefits would total $200,000 per year. The total benefits would be $270,000 per 

year. Based on average annual costs of $2,300,000, the benefit-cost ratio is 0.1. 
31 

TABLE 14.—ECONOMIC SUMMARY—BANK STABILIZATION 

Amount 

Costs: 

Construction ................................................................................................................................................ $24,500,000 

Operation and Maintenance ........................................................................................................................ $250,000 

Average Annual ........................................................................................................................................... $2,300,000 

Average Annual Benefits: 

Flood Damage Reduction ............................................................................................................................ $40,000 

Hydropower .................................................................................................................................................. $200,000 

Bank Stabilization ....................................................................................................................................... $30,000 

Fill Reduction .............................................................................................................................................. ........................

Total ........................................................................................................................................................ $270,000 

Net Benefits ......................................................................................................................................................... ¥$2,030,000 

Benefit-Cost Ratio ................................................................................................................................................ 0.1 

LEVEES

Levees would reduce overland flooding and, thereby, reduce potential flood damages and hydropower constraints. Levees were evaluated for only the Bismarck side 

of the river because of the limited development on the Mandan side of the river. 

Two levee alignments were evaluated for four levels of protection—5-, 10-, 100-, and 

500-year protection. Construction of 5- and 10-year levees is highly questionable for 

an urban area such as the south Bismarck area. Normally, only high levels of protection—100-year or greater—are considered appropriate for urbanized areas. In 

this case, however, the 5- and 10-year levees were considered because they would 

reduce the more frequent and nuisance type floods while eliminating the future constraints on Garrison hydropower production in the winter. Plate 6 shows both levee 

alignments. Alignment 1 would provide protection to all lands north of the southeast 

corner of General Sibley Island, and alignment 2 would protect all lands on the Bismarck side of the river upstream from the Lake Oahe project boundary. Average 

levee heights would vary from 4 to 5 feet for the 5-year options to approximately 

11 feet for the 500-year options. 

Table 15 presents the costs and benefits of the eight levee options. The first costs, 

including land, vary from $8.3 million to $32.0 million. The average annual costs 

vary from $720,000 to $2.8 million. The construction costs are for a rural-type levee 

design. If a 5- or 10-year levee were constructed in an urban area it would require 

a relatively flat backslope, which would result in construction costs about 25 percent 

higher than those indicated for the 5- and 10-year levees in table 15. 

The flood damage reduction benefits would vary with each option. These benefits 

would range from $80,000 for the 5-year, alignment 1 option to $710,000 per year 

for the 500-year, alignment 2 option. 

The 100- and 500-year levee options would eliminate the need to provide fill material to elevate all structures in the 100-year flood plain. This cost savings is estimated to be $60,000 per year for alignment 1 and $80,000 per year for alignment 

2. 

TABLE 15.—LEVEES ECONOMIC SUMMARY 

Item 

Levee Options 

5-year 10-year 100-year 500-year 

Alignment 1 

Costs: 

Construction ......................................................... $3,160,000 $3,360,000 $9,460,000 $13,800,000 

Land ..................................................................... $5,100,000 $5,100,000 $5,500,000 $5,500,000 

Operation and Maintenance ................................ $33,000 $36,000 $47,000 $69,000 

Average Annual .................................................... $720,000 $740,000 $1,300,000 $1,680,000 

Average Annual Benefits: 

Flood Damage Reduction ..................................... $80,000 $110,000 $490,000 $620,000 

Hydropower ........................................................... $500,000 $500,000 $500,000 $500,000 

Fill Reduction ....................................................... ........................ ........................ $60,000 $60,000 
32 

TABLE 15.—LEVEES ECONOMIC SUMMARY—Continued 

Item 

Levee Options 

5-year 10-year 100-year 500-year 

Total ................................................................ $580,000 $610,000 $1,050,000 $1,180,000 

Net Benefits .................................................................. ¥$140,000 ¥$130,000 ¥$250,000 ¥$500,000 

Benefit-Cost Ratio ........................................................ 0.8 0.8 0.8 0.7 

Alignment 2 

Costs: 

Construction ......................................................... $3,910,000 $4,250,000 $15,100,000 $22,300,000 

Land ..................................................................... $7,000,000 $7,000,000 $9,700,000 $9,700,000 

Operation and Maintenance ................................ $39,000 $42,000 $76,000 $112,000 

Average Annual .................................................... $960,000 $990,000 $2,150,000 $2,790,000 

Average Annual Benefits: 

Flood Damage Reduction ..................................... $90,000 $130,000 $570,000 $710,000 

Hydropower ........................................................... $500,000 $500,000 $500,000 $500,000 

Fill Reduction ....................................................... ........................ ........................ $80,000 $80,000 

Total ................................................................ $590,000 $630,000 $1,150,000 $1,290,000 

Net Benefits .................................................................. ¥$370,000 ¥$360,000 ¥$1,000,000 ¥$1,500,000 

Benefit-Cost Ratio ........................................................ 0.6 0.6 0.5 0.5 

All of the levee options would allow the continuation of the 20,000 c.f.s. ice-in. 

This would eliminate the potential future constraints on hydropower releases from 

Garrison Reservoir. The hydropower benefits would be the same for all eight options, or $500,000 per year. 

Total benefits range from $580,000 to $1,290,000 per year. None of the options 

have positive net benefits, and the benefit-cost ratios range from 0.5 to 0.8, as 

shown in table 15. 

GARRISON OPERATIONAL CHANGES

The all-seasons stage-frequency curve that is used to depict flood stages in the 

Bismarck area is composed of three separate curves—Garrison project release 

stages, ice-affected stages, and stages for high tributary flows combined with coincident Garrison project releases. The first curve is not as significant in computing the 

composite all-seasons curve as the other two are. Three Garrison operational change 

options were evaluated. The first option would affect the coincident release curve, 

and the other two would affect the ice-affected curve. 

—Maintain Year-Round ‘‘Normal’’ Release.—This first option consists of maintaining the daily release from Garrison Reservoir at essentially the same level 

throughout the year. Currently, the average daily releases from the reservoir 

vary considerably throughout the year. If inflows to the Fort Peck and Garrison 

projects are high, releases from Garrison Reservoir are likely to be higher over 

the next few months to allow for adequate storage space of the high inflows. 

Much higher than normal inflows generally occur in the spring, and this is the 

same time that high tributary runoff downstream from Garrison Dam is most 

likely to occur. Under the current mode of operation at this time of the year, 

the coincident Garrison release is assumed to be 35,000 c.f.s. for the 5- and 10- 

year events and 40,000 c.f.s. for the less frequent events. By limiting the average daily release to a maximum of 28,000 c.f.s., the sum of the tributary and 

Garrison coincident discharges would be lower. The open water flood elevations 

would, therefore, be lower. 

The average discharge at the Bismarck gage, based on the data accumulated since 

the filling of lake Sakakawea behind Garrison Dam, has been about 27,500 c.f.s. Because flows are reduced to about 20,000 c.f.s. each December and gradually increased during January, the average flow the remainder of the year is slightly higher—about 28,000 c.f.s.—based on a continuation of the historical flows past the Bismarck area. 

Hydrologic records reveal that a average discharge of 28,000 c.f.s. would need to 

be exceeded on the average of 1 out of every 7 or 8 years. The higher releases would 

be required to move the tributary inflows to the Fort Peck and Garrison Reservoirs 
33 

through the main stem dam system during years of very heavy runoff. A 28,000 

c.f.s. discharge could not be guaranteed, and a higher release could coincide with 

high tributary inflows downstream from Garrison Dam. 

Assuming that the 28,000 c.f.s. maximum Garrison Reservoir discharge could be 

guaranteed every year for a best-case situation, the future-conditions flood stage increases would be from 1.1 to 1.2 feet at the Bismarck gage. Under the worst-case 

situation, the coincident Garrison releases would stay at 35,000 to 40,000 c.f.s., and 

the future-conditions flood stage increases would not be reduced at all. The future 

stages, therefore, would be higher for this alternative than they would be under the 

base conditions—0.2 to 0.6 foot higher, depending on the flood recurrence interval 

and assumed worst- or best-case situation. 

A maximum release restriction of 28,000 c.f.s. would cause the Garrison Reservoir 

(Lake Sakakawea) to fluctuate over wide limits. This would require a significant 

lowering of Lake Sakakawea to maintain an adequate flood storage capacity. For 

every foot that the lake would need to be lowered, the hydropower capacity would 

be reduced by about 5 megawatts. The value of this loss per foot of head reduction 

at Garrison Dam would be about $1.9 million per year. The lake level fluctuations 

would also have negative impacts on fish production and recreation at Lake 

Sakakawea. Also, it would have a significant negative impact to the rain stem system operation. These latter impacts, however, were not quantified, and table 16 includes only the lost hydropower costs. 

TABLE 16.—ECONOMIC SUMMARY—GARRISON RESTRAINED RELEASES 

28,000 c.f.s. 11.5-foot Ice-in 20,000 c.f.s. 

Ice-in 

Annual Costs: 

Lost Hydropower ................................................................................ 1 $1,900,000 $1,200,000 ........................

Flood Damage Reduction .................................................................. ........................ ........................ $20,000 

Total .............................................................................................. $1,900,000 $1,200,000 $20,000 

Average Annual Benefits: 

Flood Damage Reduction .................................................................. $20,000 ........................ ........................

Hydropower ........................................................................................ $250,000 ........................ $500,000 

Total .............................................................................................. $270,000 ........................ $500,000 

Net Benefits ............................................................................................... ¥$1,630,000 ¥$1,200,000 ¥$480,000 

Benefit-Cost Ratio ..................................................................................... 0.1 ........................ 25 

1 Loss per foot of head reduction at Garrison Dam. 

Because winter releases would not be constrained as much as they would be for 

the baseline condition, the increased annual cost for electric power production due 

to Garrison constraints would be reduced from $500,000 to $250,000—a benefit of 

$250,000 per year. 

This option would also have flood damage reduction benefits of $20,000 per year. 

The resulting total benefits of this option would be $270,000 per year. The net benefits, however, are negative and the benefit-cost ratio is only 0.1. 

—Reduce Ice-in Stage to 11.5 Feet.—This option was evaluated to see if it would 

be effective in reducing the flood depths for the more frequent events in the 

south Bismarck area that the previous option was not effective in reducing. The 

ice-in target would be reduced to an 11.5-foot stage at the Bismarck gage instead of the current 13-foot stage. By reducing discharges to 20,000 c.f.s. during 

the critical ice-in period when stages increase dramatically because of the formation of a rough ice-in cover, the Corps of Engineers has generally been able 

to maintain an approximate 13-foot stage at Bismarck during the winter. (This 

compares to a normal open water stage of about 8 to 9 feet.) The actual icein stage for this discharge can, however, range from 11 to 14 feet. By reducing 

the current ice-in discharge to about 13,000 c.f.s., an ice-in stage of about 11.5 

feet at the Bismarck gage could be expected. This would require an average 

daily discharge reduction during the remainder of the winter (January to early 

March) of about 4,000 to 5,000 c.f.s. Average daily discharges would have to be 

increased about 2,000 c.f.s. during the remainder of the year to compensate for 

the reduced winter releases. 

As aggradation continues in the future, the ice-in discharges would have to be further reduced to continue to ice-in at 11.5 feet. By the time the future-conditions 
34 

channel size is reached, the ice-in discharge would need to be about 9,000 c.f.s. Hydropower releases for the remainder of the winter would be from 8,000 to 10,000 

c.f.s. lower than they currently are. Releases would need to be increased the remainder of the year to compensate for the reduced winter release. 

Reducing winter discharges to ice-in at 11.5 feet would be very costly. The constraints on Garrison Reservoir winter hydropower releases are estimated to be $1.7 

million per year, or $1.2 million more per year than is expected for the baseline condition. 

The 11.5-foot ice-in stage would only slightly reduce stages for the potential existing-conditions all-seasons flood events. The 5- and 10-year flood elevations would be 

reduced by 0.7 to 1.0 foot, whereas the 50- and 100-year flood elevations may increase a little because of the increased discharges in the spring, summer, and fall. 

This modification would reduce the potential future-conditions 5- and 10-year 

flood stages by 0.2 and 0.3 foot, respectively, and the potential 50- and 100-year 

flood elevations would not be affected. Almost no flood damage reduction benefits 

would be expected. This option would provide no hydropower benefits. 

Table 16 also presents the economic summary for reducing the ice-in stage to 11.5 

feet. The benefit-cost ratio of this option would be essentially 0. 

—Restrain Ice-in Release to 20,000 c.f.s.—This option was evaluated to determine 

if it would be feasible to continue releasing 20,000 c.f.s. during the critical icein period to eliminate the projected Garrison hydropower generation constraints. Under this option, the potential residual flooding for the more frequent 

events would be expected to increase because the ice-affected discharges would 

be the same as they currently are and the river stages would increase as 

aggradation continues. 

Flood stages for the more frequent events would be higher under this option than 

they would be for the baseline condition. The 5-year stage at the Bismarck gage 

would be 0.9 foot higher than under the assumed baseline condition, and the 10- 

year stage would be 0.7 foot higher. Stages between the gage and the Lake Oahe 

project boundary would be 0.4 to 0.6 foot higher for the 5- and 10-year events. The 

stages for 50-year and greater events would not be affected by this restrained release option. 

Potential flood damages would be increased by $20,000 per year with this alternative. Therefore, this alternative would have flood damage reduction benefits 

equaling a minus $20,000—or a cost of $20,000 as shown in table 16. The expected 

future hydropower constraint at Bismarck would be removed, and this alternative 

would eliminate the expected $500,000 increase in hydropower production costs for 

the region. The benefit-cost ratio of this alternative would be 25, as shown in table 

16. 

OAHE OPERATIONAL CHANGES

The Lake Oahe pool produces a backwater that affects river stages upstream from 

the pool. Thus, several lower pool levels were evaluated to determine if flood stages 

could be reduced in the south Bismarck area. These pool level reductions were 5, 

10, and 15 feet. 

The Lake Oahe pool effects diminish in the south Bismarck area as the Missouri 

River discharges increase. For example, at 28,000 c.f.s., the historic average, stage 

reductions of 0.7 foot would be expected at the project boundary if Lake Oahe were 

lowered 15 feet; a reduction of only 0.1 foot would occur at the Bismarck gage. However, the 5-year and less frequent flood stages would not be reduced upstream from 

the Lake Oahe project boundary with even a 15-foot lower Lake Oahe pool. Actually, 

the 5- and 10-year stages between the Bismarck gage and the project boundary 

would be 0.4 to 0.6 foot higher than those that would result from the baseline condition. 

Lowering the Lake Oahe pool would reduce the hydropower generating capacity 

of the Oahe project. For example, a 15-foot pool level reduction would reduce the 

capacity from 595 megawatts to 524 megawatts—a reduction of 71 megawatts. It 

is estimated that it would cost in excess of $70 million for a utility to replace this 

lost capacity with a coal-fired unit. The average annual cost to provide the replacement capacity is estimated to be about $5.8 million. 

This alternative would have negative flood damage reduction benefits of $20,000 

per year and no hydropower benefits. This alternative would provide no positive 

benefits and would he very costly. 
35 

LAND ACQUISITION

Flood damages would be reduced by relocating development out of the flood plain. 

Two options were considered for relocating the development—acquire the future-conditions 5-year flood plain and to acquire the future-conditions 10-year flood plain. 

The future-conditions all-seasons 5-year flood limits include 3,770 acres, and the 

10-year flood limits include 4,880 acres. Acquisition of the area influenced by the 

future-conditions 5- and 10-year events, however, could total as much as 6,000 and 

7,000 acres, respectively. Depending on location, depth of flooding, and other factors, 

flowage easements could be considered for some areas and fee title acquisition for 

others. The areas that were most likely to be considered for acquisition of flowage 

easements rather than fee title were not delineated. 

Based on a preliminary estimate, fee title acquisition of the 5-year flood plain is estimated to cost $23.1 million. Acquisition of the 10-year flood plain is estimated 

to cost $34.2 million. Based on these costs, the estimated average annual costs for 

acquisition of the 5- and 10-year flood plains are $1.9 million and $2.9 million, respectively. Flood damage reduction benefits are estimated to be $110,000 and $140,000 per 

year as a result of eliminating the development from the 5- and 10-year flood plains, 

respectively. Significant flood damages could continue to accrue because larger, lessfrequent floods could continue to damage the structures in the remainder of the 

south Bismarck area. Acquisition of the 5- and 10-year flood plains would reduce 

the need for fill material for raising future housing construction in Bismarck; the 

estimated cost savings of fill material is $30,000 per year. 

Hydropower benefits would accrue because potential future Garrison winter hy- dropower generation constraints would be removed. These benefits are $500,000 per 

year. 

Table 17 presents the economic summary for the land acquisition alternative. Neither option has positive net benefits. The benefit-cost ratios are 0.3 and 0.2 for the 

5- and 10-year options, respectively. 

TABLE 17.—ECONOMIC SUMMARY—LAND ACQUISITION 

Item 

Options 

5-year 10-year 

Costs: 

Acquisition ...................................................................................................................... $23,100,000 $34,200,000 

Average Annual .............................................................................................................. $1,940,000 $2,870,000 

Average Annual Benefits: 

Flood Damage Reduction ............................................................................................... $110,000 $140,000 

Hydropower ..................................................................................................................... $500,000 $500,000 

Fill Reduction ................................................................................................................. $30,000 $30,000 

Total ........................................................................................................................... $640,000 $670,000 

Net Benefits ............................................................................................................................ ¥$1,300,000 ¥$2,200,000 

Benefit-Cost Ratio ................................................................................................................... 0.3 4.2 

FLOOD PLAIN MANAGEMENT

There are two flood plain management measures that could be used to minimize 

the flood damage potential in the south-Bismarck area These measures include (1) 

raising the required elevation of any future flood plain development from 1 foot 

above the 100-year flood level to some higher level and (2) raising the streets and 

access roads in flood-prone areas to assure access to and from these areas during 

periods of flooding. Neither of these measures would reduce the area inundated during any flood. One of the measures, raising future development, would, however, reduce damages to future development in the flood plain. 

A third measure, flood proofing, was considered. It would, however, not be practical or feasible to flood proof existing structures by making structural modifications 

or by raising the structures. The frequency, depths, and duration of flooding would 

not justify the substantial structural modifications. 

Currently, any development in the 100-year flood plain must be placed on fill or 

elevated by other means to 1 foot above the existing-conditions 100-year flood level. 

As the channel aggradation takes place, the 1 foot above the potential existing-conditions 100-year flood will gradually diminish. If the required fill elevation for future development were raised a total of 3.5 to 4 feet above the existing-conditions 
36 

100-year flood elevation, the future structures would be above the future-conditions 

500-year flood level. Although this would not affect the existing average annual 

flood damages, it would provide estimated benefits of $360,000 to future development at an estimated cost of $110,000. The benefit-cost ratio of this measure is 3.3. 

Most of the major access roads throughout the flood plain are somewhat higher 

than the natural ground elevations; in general, they provide access to and from most 

areas up to about the 5-year event under existing conditions. However, most of the 

streets in the subdivisions and other developed areas are basically at natural 

ground level and do not provide adequate access during flooding. With the additional channel aggradation that will gradually occur, these roads and streets will 

provide even more restricted access during periods of flooding. Raising all access 

roads and streets to some elevation—such as the 100-year existing-conditions flood 

level—would ensure that, under future channel conditions, the roads and streets 

would still provide access during the 50-year flood event. To raise the roads and 

streets to the existing-conditions 100-year flood level would require raises ranging 

up to 3 feet. The extent and cost of these raises have not been estimated. 

STUDY CONCLUSION

The course of action to be followed by the Corps of Engineers is to continue to 

reduce releases from Garrison Reservoir at critical high discharge periods at Bismarck—when flows from tributaries downstream from Garrison Dam could cause 

flooding at Bismarck and during winter ice-in (retain 13-foot target). Additional 

flood plain management measures should be considered by the city of Bismarck, 

Burleigh County, and those developing in the flood plain. These measures would 

limit future increases in flood damages and increase the safety of persons living in 

the flood plain. These measures include raising new development more than the required 1 foot above the potential existing-conditions 100-year flood elevation and 

raising the access roads to areas of extensive development. Also, those living or having businesses in the flood plain should continue to participate in the Federal Flood 

Insurance Program to minimize personal loss should flooding damage their property. 

RECOMMENDATION

(To be prepared following public comment.) 
37 
38 
39 
40 

Mr. GUNSCH. The Bottom line of that study, the conclusion was 

to change reservoir operations to minimize releases during critical 

high discharge periods and to recommend communities consider 

implementing additional criteria for flood plain development, raising access roads, encouraging participation in the National Flood 

Insurance Program. Given the March 2009 event we have to question if operational changes alone are adequate to address the ice 

jam events at this point. 

The 1985 study actually predicted increases in the base flood elevations for the Bismarck/Mandan area. And between 1981 and 
41 

1998 which is the two data sets for the 1985 and 2005 flood insurance studies which is a 17-year period, the elevations that were 

predicted in that report were already reached. So there are a number of professionals who agree this is not the end of the increases 

that will be experienced. Therefore more needs to be done before 

the situation deteriorates further. And we’re already 10 years past 

the most recent data set. 

More recently under section 108 Missouri River Protection Improvement Act 2000, title VII enlisted the professional engineering 

services of Louis Berger Group to complete a report entitled, Impacts of Siltation on the Missouri River in the State of North Dakota Report 2009. A copy of this report is also provided for the 

record. As it documents and justifies many of the concerns that 

have been expressed here this evening. 

[The information follows:] 

IMPACTS OF SILTATION OF THE MISSOURI RIVER IN THE STATE OF NORTH DAKOTA

SUMMARY REPORT

1.0 INTRODUCTION

The U.S. Army Corps of Engineers (USACE) tasked The Louis Berger Group Inc. 

(Berger) to assess impacts of sedimentation in the Missouri River Basin within the 

State of North Dakota. This assessment is intended to meet the level of effort defined in the Missouri River Protection and Improvement Act. The assessment had 

two main objectives. First, to identify sources and deposit locations of sediment 

within the Missouri River Basin in the State of North Dakota, utilizing existing 

data and information. Second, to analyze potential impacts of sedimentation on important issues and resources including: Federal, tribal, State and regional economies; recreation; hydropower generation; fish and wildlife; flood control; and Indian 

and non-Indian historical and cultural sites. 

For each resource area identified above, Berger prepared a detailed report. This 

document is a summary of those efforts and presents the key findings. We encourage the reader to refer to each report, provided in full as Appendices A through G 

at the end of this summary report. Full details of the project analyses and discussions are presented in each of those reports. 

This summary report is organized as follows: Section 2.0 describes the study area 

that was evaluated; Section 3.0 provides a summary of sources, deposits, and locations of erosion along the Missouri River; Section 4.0 discusses the economic impacts 

of sedimentation and erosion; Section 5.0 summarizes the impacts of sedimentation 

and erosion on recreational resources; Section 6.0 summarized the impacts of sediment and erosion on hydropower; Section 7.0 summarizes impacts to fish and wildlife; Section 8.0 summarizes impacts to flood control; Section 9.0 discusses impacts 

to Indian and non-Indian historical and cultural resources; and Section 10.0 discusses recommendations. 

2.0 STUDY AREA

The study area was defined by the USACE to include the watershed of the main 

stem of the Missouri River from the North Dakota-South Dakota border on the 

downstream end to the Montana-North Dakota border on the upstream end. The 

study area includes tributaries of the Missouri River, Lake Sakakawea, and Lake 

Oahe. 
42 

FIGURE 1.—Location of the Study Area 

3.0 SOURCES, DEPOSITS, AND EROSION LOCATIONS

The first task of this study was to conduct an assessment of potential sediment 

sources, deposits, and erosion locations for the main stem Missouri River in North 

Dakota. The analysis showed that potential sediment sources for the Missouri River 

in North Dakota include: (1) upper reaches of the Missouri River in Montana; (2) 

the Yellowstone River watershed (largest watershed draining into the Missouri 

River); and (3) the remaining watersheds in North Dakota draining into the Missouri River between the Garrison Dam and the city of Bismarck. 

The sediment load assessment showed that the Yellowstone River and the Missouri River in Montana delivered the largest percentage of sediment loads to the 

main stem Missouri River in North Dakota. The Yellowstone River and the portion 

of the Missouri River in Montana accounted for more than 86 percent of the total 

delivered sediment load, whereas the watersheds within the study area (not including the Yellowstone River watershed) accounted only for approximately 4 percent of 

the total delivered load in North Dakota. Sediment load from in-stream erosion 

within the Missouri River accounted for the remaining 10 percent. Table 1 summarizes the sediment sources and their load percentages. 

TABLE 1.—SEDIMENT LOADS AND THEIR FRACTIONS IN THE MISSOURI RIVER, ND 

Source 

Estimated Sediment Load (million tonnes/year) Percentage of 

Total Delivered 

Sediment Load 

Yellowstone River 1 .................................................................................................................. 29.1 64.7 

Missouri River from Montana 2 ............................................................................................... 9.5 21.1 

Watersheds within the Study Area 3 ....................................................................................... 1.7 3.8 

In-stream Erosion within the Garrison Reach 4 ..................................................................... 4.7 10.4 

Total ........................................................................................................................... 45.0 100.0 

1 Based on estimated sediment loads by USACE at USGS station 06185500 (Missouri River at Culbertson, Montana) and reduction of 30

percent. 2 Based on estimated sediment loads by USACE at USGS station 06329500 (Yellowstone River at Sidney, Montana) and reduction of 30 per- cent. 3 Based on 5 year average sediment load using the Generalized Watershed Loading Functions Model (GWLF); Includes all watersheds draining into the Missouri River in North Dakota except for the Yellowstone River. 4 Based on the difference between the total annual sediment load at the city of Bismarck USGS station (6342500) and the total delivered sediment load of the four sub-watersheds draining between Garrison Dam and the City of Bismarck. 

Additional analysis to identify areas of low, medium, and high levels of 

aggradation along the main stem sections of the Missouri River was conducted, in-
43 

cluding all sources identified in Table 1. The aggradation areas were plotted on 

maps and presented in Appendix A, attached to this document. In addition, the following conclusions were drawn from the analysis of aggradation areas. 

—The majority of the identified aggradation areas were located upstream of Lake 

Sakakawea close to the Montana/North Dakota border and in the vicinity of watersheds showing large amounts of delivered land-based sediments. These 

aggradation areas in the upper reaches of the river in North Dakota were predominantly caused by the delivery of sediment loads from the Yellowstone River 

and the Missouri River in Montana. 

—The area between the city of Bismarck and Lake Oahe showed several 

aggradation areas with mostly low and moderate aggradation potential. Potential sources for sediment deposition in these areas were caused by in-stream 

erosion of the Missouri River below the Garrison Dam and by land-based sediments originating from the Painted Woods-Square Butte, Knife River, Heart 

River, and Cannonball River watersheds. The largest source of these 

aggradation areas are likely sediment deposits from eroded riverbeds and riverbanks, due to the impact of hydropower use at Garrison Dam. 

—Areas that showed little or no aggradation were generally located within the 

center of the reservoirs (Lake Sakakawea and Lake Oahe) and in the stream 

reach between Garrison Dam and the city of Bismarck in which in-stream erosion dominates (90 percent of the total sediment load originates from in-stream 

erosion). 

4.0 IMPACTS TO FEDERAL, TRIBAL, STATE, AND REGIONAL ECONOMIES

Berger evaluated the direct economic impacts associated with increased sedimentation and erosion along the Missouri River in the State of North Dakota. The 

evaluation included a qualitative discussion on whether or not the direct economic 

impacts are relevant in scale and location to Federal, tribal, State, and regional 

economies. For instance, certain impacts may be relevant to tribal or regional economies due to the location of impacts, but may not be relevant at the State or national 

levels due to the size of the impact. Where possible, these distinctions were made 

with all direct economic impacts identified. 

The potential economic impacts were based in part on the impacts to other resource areas identified by the other subtasks. In addition, Berger completed a literature search and interviews with subject matter experts to identify additional economic impacts that may not have been identified by the other analyses. The resources and activities that may be impacted by sedimentation and that may have 

economic implications include: 

—Land Use 

—Coal-fired Power Production 

—Hydropower Production 

—Recreation 

—Water Supply Intakes 

Based on the analysis, Berger concluded that the most significant economic impact likely to occur is from potential increase in flooding risk caused by sedimentation in and around the Bismarck and Mandan areas, especially in winter. Other resources and activities such as electric power production (hydro and thermal), recreation, water supply and land use are also experiencing impacts. However, none of 

these impacts appear as significant as the potential impacts of increased flooding 

risk in urbanized areas. Berger was unable to fully quantify the potential economic 

impacts to recreation visitor use and agricultural use due to a lack of quantifiable 

data and would suggest these resources be studied further. 

The results of the economic impact analysis are summarized in Table 2. Additional information on economic impacts is provided in Appendix B. 
44 

TABLE 2.—POTENTIAL ECONOMIC IMPACTS OF SEDIMENTATION ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Resource Potential Impact 

Impact to Economy 

Timeframe Comments 

Federal State Local Tribal 

Agricultural Land Use ............................................................................................... Loss of Productivity of Agricultural Lands. ............ ............ X X Short-term ...Flood Control ............................................................................................................. Increased Flooding ............. ............ X X ............ Long-term .... Increased flooding potential can lead 

to costly buyouts, increased insurance costs, and reduction in property values. 

Coal-fired Power Plants ............................................................................................ Reduction in generation capacity. ............ ............ X ............ Long-term .... Loss in revenue or increase in costs to meet contract demands. Hydropower ................................................................................................................ Reduction in generation capacity. ............ X X X Long-term .... Increased flooding potential can reduce hydropower production, especially 

during colder months. 

Recreation ................................................................................................................. Increased maintenance 

costs for recreational facilities.

............ X X X Long-term .... Increased cost to dredge and maintain 

facilities affected by sedimentation. Impacts to visitor behavior are unknown. 

Water Supply ............................................................................................................. Increase operation and 

maintenance costs.

............ ............ X X Long-term .... Small number of intakes are impacted 

by sedimentation, causing an increase in operation and maintenance costs. 

Note.—Fish and wildlife resources have not been included in this table describing economic impacts of sedimentation for two reasons. First, economic impacts associated with affects of sedimentation on fish and wildlife would occur with 

a reduction in recreational activities (e.g. fishing, bird watching). This issue is addressed somewhat under Section 5.0—Recreation. The economic impact associated with a reduction in native species due to sedimentation cannot be quantified at this time due to lack of data. 
45 

5.0 RECREATION

The evaluation of impacts on recreation resources conducted by Berger revealed 

that drought conditions and sedimentation/siltation processes can result in access 

restrictions and temporary park or access closures. However, it appears that prolonged drought conditions have a much larger impact on recreational use than on 

sedimentation. However, drought was not a focus of this analysis. 

Even temporary closures of recreational sites can prevent access to areas within 

the river and reservoirs, resulting in direct impacts to the recreation resources. The 

loss of boater access results in longer drives to launch boats, trip cancellation, poor 

aesthetics, and safety hazards to those using the Missouri River and the reservoirs 

in North Dakota. In addition, boat access site managers are forced to spend more 

time and resources operating and maintaining the boat ramps, keeping them free 

of sediments to maintain boater access. Bays or arms just off the main channel have 

historically been the primary location for boater access; however, these areas are 

susceptible to sediment aggradation as reported in interviews conducted for this research. It is important to note that these areas were not identified by Berger when 

evaluating sediment sources and locations, so the number of visitors affected by 

sedimentation is difficult to estimate and could likely be much higher. It is also important to note that sedimentation can be a nuisance at boat ramps, increasing 

operational and maintenance costs for the users; however, the reservoirs still provide the greatest amount of flat water recreation opportunities in the state of North 

Dakota so that once on the water, recreationists may still report satisfactory trips. 

In response to drought conditions, boat ramps have been extended or relocated to 

accommodate for low water levels, and the State of North Dakota actively maintains 

access sites for the purpose of maximizing recreational opportunities. Extension or 

relocation would also accommodate for sedimentation build up at boat ramps within 

the study area, though Berger was unable to determine if any of the ramps were 

extended solely due to increased sedimentation. Erosion and sedimentation of boat 

ramps also causes problems for recreational opportunities in other areas along the 

reservoirs that were not identified by Berger (e.g. bay areas). Overall, however, tremendous opportunities exist in the area for flat water recreation and access to the 

reservoirs and rivers. From the data and information available, it was not possible 

to measure if increased sedimentation is causing a decline in recreational visitor 

days or a change in visitor behavior (e.g. visits to alternative areas). This information is needed to quantify economic impacts. 

It should be noted that sediment load is critical to the formation of sandbars. 

Sandbars are, in turn, critical fish habitat not only for walleye but also for a host 

of native fish species. From an angling perspective, sand bars often provide prime 

fishing spots to catch walleye. Any recommendations should consider both the positive and negative impact of sedimentation. 

Table 3 summarizes the key findings related to recreational resources. 
46 

TABLE 3.—IMPACT OF SEDIMENTATION ON RECREATION RESOURCES 

Direct Impact Significance Timeline Recommendations 

Ramp or Access Closure ................. Lack of boater access results in longer drives to 

launch boats, trip cancellation, poor aesthetics, and safety hazards to those using the Missouri River. Boat access site managers are forced to spend more time and resources operating and maintaining the boat ramps, keeping them free of sediments to maintain boater access.

Parks and access areas are predominantly used 

in the summer; therefore, summer would have the greatest level of impact. Because sedimentation processes occur throughout the year, however, impacts to access areas would be ongoing.

For long-term planning purposes, identify and prioritize areas, that 

are currently susceptible to sediment aggradation and that are close to population centers (e.g. Fort Stevenson State Park), and identify alternative ramp sites that would result in less aggradation on the ramps. 

Conduct an additional study of visitors’ willingness to travel in the 

event that popular boat ramps are closed. Identify the proximity to nearby alternatives. 

Evaluate the benefits of extending or relocating boat ramps depending on the information gathered from completing the first 

two recommendations. 

Evaluate the impact of closing ramps at sites that do not have 

viable alternative locations for new ramps and that have regular dredging needs. 

Underwater hazards ........................ Shallow water due to sediment deposition poses a 

risk to boaters and boating equipment.

Dynamic and dependent on reservoir and river 

elevations. Summer peak boating season with low lake and river levels poses the greatest risk.

Work with the North Dakota Game, Fish, and Parks (NDGFP) Department and recreation non-government organizations (NGOs) 

to evaluate options of educating the boating public. Consider: (a) Posting signage to make the public aware of the possible hazard. (b) Marking of obstructions in high-use, high-risk areas. (c) Updating bathymetric mapping efforts. 
47 

6.0 HYDROPOWER

Hydropower facilities along the Missouri River in North Dakota consist of the 

Garrison Dam and its reservoir, Lake Sakakawea. In addition, hydropower operations in North Dakota are affected by the operation of Oahe Dam in South Dakota 

because Lake Oahe extends into southern North Dakota up to just south of the city 

of Bismarck when the pool is full. Annual gross power production at the Garrison 

Dam averaged 2.29 million megawatt hours (MWh) from 1967 (2 years after Lake 

Sakakawea was filled) through 2007. However, hydropower operations at Garrison 

Dam have generally decreased over time to 1.31 MWh in 2007 due to drought. The 

main exception was a period in the mid-1990s with high precipitation in the upper 

Missouri River watershed. Peak months of outflow and the resulting energy generation are December, July, and August due to high power demand. 

The electricity generated at the Garrison facility is marketed by the Western Area 

Power Administration (WAPA), an agency of the Department of Energy (Western). 

Revenues are highest during the peak generation months in winter and summer. 

The total revenues from energy generated at Garrison Dam in the last 5 years (2003 

to 2007) ranged from $15 million to $22 million. Highest annual revenues were generated during the wet year 1996 with $43 million. 

The evaluation completed by Berger focuses on three potential impacts of sedimentation and erosion on hydropower generation, including: 

—Loss of Storage in Lake Sakakawea.—Lake Sakakawea traps nearly 100 percent 

of the sediment that enters the reservoir. Most of the sediment originates from 

the Missouri River and the Yellowstone River, a tributary to the Missouri River. 

This includes sediment that is eroded from the bank and bottom of the Missouri 

River, downstream of the Fort Peck Dam. The USACE estimated a storage loss 

rate of 25,900 acre-feet/year (or 0.11 percent per year. At this rate, the life expectancy of Lake Sakakawea is approximately 900 years before it is completely 

filled. This value is a first-order estimate only, as the life expectancy depends 

on a number of variables such as sediment trapping efficiency (which decreases 

over time), climate variability over time, and sediment contributions from the 

watershed of Fort Peck Dam. However, this first-order estimate indicates that 

this issue is not expected to be a concern to the hydropower operations at the 

Garrison facility during the short or intermediate term. 

—Entrainment of Sediment Into the Turbines at Garrison Dam.—With an annual 

loss of storage capacity by 0.11 percent, and with most of the deposition occurring in the upper reaches of the reservoir, impacts to the hydropower facility 

intakes are not expected in the short or intermediate future. As a result, the 

USACE does not currently have specific sediment management methods or sediment control facilities at their hydroelectric facilities. 

—Reduced Releases at Garrison Dam in Winter Due to Flooding Risk From Sediment Aggradation.—Siltation in the reach between Garrison Dam and Lake 

Oahe has resulted in increased risk of flooding downstream. The Missouri River 

typically freezes in December, remains frozen in January and February, and 

starts to thaw in March and April. A large consideration in flow releases is the 

potential formation of ice dams. As a result, aggradation of the river channel 

in the headwaters of Lake Oahe caused a slight decrease in electricity generation in the colder months as compared to the warmer months. 

The following actions are recommended to reduce impacts of sedimentation on hydropower production at the Garrison Dam facility (Table 4). 
48 

TABLE 4.—IMPACTS OF SEDIMENTATION ON HYDROPOWER PRODUCTION 

Direct Impact Significance Timeline Recommendations 

Sedimentation of Lake Sakakawea .......................... Minimal .................. Impacts are not expected to occur until well into the future ......... No Action Recommended. Turbine Impacts ....................................................... Minimal .................. Impacts are not expected to occur until well into the future ......... No Action Recommended. Reduced Releases at Garrison Dam ........................ Major ...................... Short to Long Term ........................................................................... Continue to collect monitoring data in order to apply an adaptive 

management approach at the Garrison Dam facility. 

Conduct small-scale dredging in local areas impacted by flooding. Review existing flood plain designation and zoning to reduce development in flood-prone areas. Quantitatively evaluate if higher elevations of Lake Oahe due to 

aggradation will reduce flow velocities. 
49 

7.0 FISH AND WILDLIFE

The Missouri River system is a complex system that includes a suite of ecological 

regions. North Dakota contains one dam, Garrison Dam, and its associated reservoir, Lake Sakakawea. The reservoir known as Lake Oahe, formed by the Oahe 

Dam in South Dakota, also extends into North Dakota from the south. From an ecological perspective, the Missouri River in North Dakota may be thought of as having 

four parts: 

—The Williston Reach.—The riverine segment close to the Montana border, into 

which the Yellowstone River flows and which flows into Lake Sakakawea. 

—Lake Sakakawea.—The reservoir formed by Garrison Dam (closed in 1953), the 

entire range of which is within the State of North Dakota. 

—The Garrison Reach.—The riverine segment from Garrison Dam to the headwaters of Lake Oahe. 

—Lake Oahe.—The reservoir formed by Oahe Dam in South Dakota (closed in 

1958) and which is in both North Dakota and South Dakota. 

Analyzing the impacts of sedimentation to fish and wildlife defines species as two 

groups of animals: those that constitute a conservation concern, including State and 

federally listed species, and those that are important for recreational purposes 

(hunting and fishing). These are hereafter referred to as ‘‘Conservation Species’’ and 

‘‘Recreational Species,’’ respectively. 

An increased sediment load in the reservoirs indicates increased sediment 

aggradation due to decreased maximum water velocity associated with reservoirs 

and the resulting limited ability of reservoirs to transport sediment downstream. 

Aggradation would cause an increase in delta size (Palmieri et al., 2001, cited in 

Kaemingk et al., 2007) and could lead to sediment accumulation behind dams. An 

increased sediment load would also increase turbidity in the inter-reservoir reaches 

and in the headwaters. The remainder of the reservoir would remain clear, due to 

the low water velocity causing suspended sediment to settle (Blevins, 2006). The impacts on different species of fish and wildlife would not be uniform, as some species 

benefit in some reaches while others are negatively affected. These differences are 

the result of a particular species’ life-cycle characteristics as they relate to each particular portion of the river. 

Many of the key recreation species of fish require clear and sediment-free water 

for their prosperity. Therefore, sedimentation and increased turbidity have negative 

impacts on their populations. Current conditions do allow, however, for abundant 

recreational fisheries. In addition, an increased sediment load could presumably 

have benefits for some of the conservation species that are adapted to life in a 

turbid environment. Other physical factors being equal, though, increased sediment 

loading alone is not likely to be sufficient to restore or support the populations of 

these species. 

Other conservation species would benefit from an increase in the amount of sandbar habitat available. Increased sedimentation could potentially generate new sandbar habitat; in many areas, the deficit of sandbar habitat results in reduced sediment load due to sediment retention by dams (NRC, 2002). Colonization of sandbars 

by cottonwood and willow trees constitutes another important part of habitat generation for many species. However, such colonization would require seasonal floods 

of a magnitude commensurate with those of the Missouri River during pre-regulation times (Johnson, 2002; Bovee and Scott, 2002). Thus, increased sedimentation 

alone may not generate suitable sandbar habitat unless a hydrologic regime is allowed to occur which suits cottonwood and willow tree colonization. 

The results of the analysis of impacts to fish and wildlife are summarized in Table 

5. 
50 

TABLE 5.—IMPACT OF SEDIMENTATION ON KEY SPECIES 

Species Positive impact No significant impact 

Positive impact if siltation increases riparian forest habitat; otherwise no impact Negative impact Siltation positive, but require other environ- mental factors as well Positive Impact if sil- tation increases sand- bar habitat River sections where spe- cies predominates 

Conservation Priority Level I 

Blue sucker ............................................................ ................................ ................................ ................................ ................................ X ................................ Oahe and Garrison Sturgeon chub ....................................................... ................................ ................................ ................................ ................................ X ................................ Williston only Sicklefin chub ........................................................ ................................ ................................ ................................ ................................ X ................................ Williston only 

Conservation Priority Level II 

Bald eagle ............................................................. ................................ ................................ X ................................ ................................ ................................ N/A Golden eagle .......................................................... ................................ ................................ X ................................ ................................ ................................ N/A Least tern .............................................................. ................................ ................................ ................................ ................................ ................................ X N/A Piping plover .......................................................... ................................ ................................ ................................ ................................ ................................ X N/A Red-headed woodpecker ........................................ ................................ ................................ X ................................ ................................ ................................ N/A River otter .............................................................. ................................ X ................................ ................................ ................................ ................................ N/A Flathead chub ........................................................ ................................ ................................ ................................ ................................ X ................................ Williston only Paddlefish .............................................................. ................................ ................................ ................................ ................................ X ................................ Williston, Sakakawea, 

Oahe 

Pallid sturgeon ...................................................... ................................ ................................ ................................ ................................ X ................................ Yellowstone River and 

Williston 

Conservation Priority Level III 

Smooth softshell turtle .......................................... ................................ ................................ ................................ ................................ ................................ X N/A False map turtle .................................................... ................................ ................................ ................................ ................................ ................................ X N/A Flathead catfish .................................................... ................................ ................................ ................................ ................................ X ................................ Oahe only 

Recreational Species 

Beaver .................................................................... ................................ ................................ ................................ ................................ ................................ ................................ N/A Canada goose ........................................................ ................................ X ................................ ................................ ................................ ................................ N/A Channel catfish ..................................................... X ................................ ................................ ................................ ................................ ................................ Oahe Chinook salmon ..................................................... ................................ ................................ ................................ X ................................ ................................ Sakakawea Muskrat .................................................................. ................................ ................................ ................................ ................................ ................................ ................................ N/A Northern pike ......................................................... ................................ ................................ ................................ X ................................ ................................ Sakakawea Sauger .................................................................... X ................................ ................................ ................................ ................................ ................................ Sakakawea, Oahe Walleye ................................................................... ................................ ................................ ................................ X ................................ ................................ Sakakawea, Oahe White bass ............................................................. ................................ ................................ ................................ X ................................ ................................ Sakakawea, Oahe 
51 

8.0 FLOOD CONTROL

Berger evaluated the potential impacts of siltation on flood control in the Missouri 

River Basin within the State of North Dakota. The analysis focused on a review of 

Flood Insurance Studies (FIS) prepared by the Federal Emergency Management 

Agency (FEMA) for the Bismarck, North Dakota, area to analyze changes in water 

surface elevation and its effects on flooding. 

Flood control issues within the Missouri River for the Bismarck, North Dakota, 

area are caused or affected by (1) open-water seasonal flooding from Garrison Dam 

operations, (2) open-water seasonal flooding from tributaries, and other residual 

drainage areas below Garrison Dam, combined with releases from Garrison Dam, 

(3) flooding, resulting from ice jams and ice conditions, and (4) flooding caused by 

aggradation in the upper reaches of Lake Oahe. 

Siltation in the reach between Garrison Dam and Lake Oahe has resulted in increased risk of flooding in the downstream reach between the dam and the headwater of Lake Oahe. Because of this sediment aggradation, the impact of ice dams 

on seasonal flooding has increased and is expected to continue. As a means to 

counter this impact, carefully sequenced water releases during the winter months 

are made to prevent flooding caused by ice dams. Water release from Garrison Dam 

is also used to provide flood control during other seasons as well. 

Within the Garrison Reach, the upstream and downstream controls (mainstem 

dams) provide upstream clear-water release and a downstream backwater. This results in scouring and lowering of the degradation zone of the channel in the upstream reaches and an aggradational effect in the lower portion of the reach. The 

elevation of the channel bed is raised in the aggradation zone. The channel begins 

to display braided characteristics within a meandering regime as it becomes wider 

and shallower, a result of the backwater condition and delta formation at the headwater of Lake Oahe. 

9.0 INDIAN AND NON-INDIAN HISTORICAL AND CULTURAL SITES

Berger assessed the potential types of cultural resources within Burleigh, 

Emmons, Mclean, Morton, Oliver, Williams, Dunn, McKenzie, Mercer, Mountrail, 

and Sioux Counties. The areas included USACE jurisdiction areas at Lake Oahe 

and Lake Sakakawea, the Standing Rock Sioux and Fort Berthold Reservations, as 

well as designated aggradation areas of the Missouri River corridor. The North Dakota Historical Society and USACE completed file searches between January and 

March 2009. Site types encountered during the files searches include prehistoric 

sites, historic sites, multi-component sites (sites with both prehistoric and historic 

materials), and sites that cannot be assigned to a specific time period (‘‘unknown’’). 

It should be noted that, while previous investigations have been conducted, there 

are portions of the project area where no surveys have been completed, particularly 

on private or tribal lands. 

The research conducted by USACE revealed that prior investigations have been 

undertaken within the aggradation areas; 148 sites have been recorded within the 

Lake Oahe portion of the project area, and 1,216 sites have been previously recorded 

within the Lake Sakakawea portion of the project area. The sites at Lake Oahe consist of 90 prehistoric, 31 historic, 17 multi-component, and 10 unknown sites. The 

sites at Lake Sakakawea consist of 835 prehistoric, 120 historic, 54 multi-component, 2 paleontological, and 205 unknown sites. 

Of the 144 sites recorded at Lake Oahe, 123 sites are eligible for inclusion in the 

National Register, while 21 sites remain unevaluated for eligibility. Of all sites recorded at Lake Sakakawea, the number of sites eligible for inclusion in the National 

Register is 22. The number of sites unevaluated for inclusion is 1,194. The research 

conducted by the North Dakota State Historic Preservation Offices (NDSHPO) revealed that more than 70 sites have been previously recorded on private land portions subject to aggradation along the mainstem of the river within the project area. 

Of the 76 sites, 4 sites are eligible for inclusion in the National Register, 4 sites 

are ineligible for inclusion in the National Register, and 68 sites are unevaluated. 

While siltation can effectively and beneficially protect and preserve some sites, 

such as subsurface archaeological sites, often the subsequent wind or water erosion 

is destructive. Recent drought conditions have resulted in lower than normal lake 

levels in Lake Oahe, changing the upstream character of the reservoir from reservoir to riverine character. Of particular concern is cut bank erosion. Archaeological sites and historic structures along reservoir and river banks can slowly or 

drastically deteriorate as the shoreline erodes. Indian and other ethnic group traditional-use or ceremonial areas can be affected by both siltation (covering the resource or area) and erosion (depleting the resource or area). Other potentially destructive factors to cultural resources are agricultural and grazing leases close to 
52 

the USACE jurisdictional boundary (Gilbert personal communication, 2009). Because Indian and non-Indian site resources are non-renewable, almost all impacts 

resulting from siltation and erosion are considered adverse or negative. In cultural 

resource terms, the integrity, or composition and cohesiveness, of a site is crucial 

to a site’s significance and intrinsic value to understanding our history or prehistory. The magnitude of the impact to the integrity of a site can vary from minor 

(e.g., artifact displacement resulting from sediment movement) to substantial (e.g., 

complete removal of a stone circle, stone cairn, or structural foundation resulting 

from an erosion event). 

According to USACE and NDSHPO records of known Indian and non-Indian sites 

along the reservoirs and mainstem of the river within potential areas of aggradation 

and erosion, USACE and other researchers have recorded erosion, inundation, 

bioturbation, and effects of farming, construction, and vandalism. 

Table 6 summarizes the impacts identified in the evaluation of cultural and historic resources and suggested recommendations on how to mitigate such impacts. 
53 

TABLE 6.—SUMMARY OF IMPACTS AND RECOMMENDATIONS 

Impact Significance Timeline Recommendation 

Inundation (partial, periodic, complete) ..................... Substantial ....................... Long term—for life of jurisdiction ....................................... Monitor at low water levels; data recovery as needed Erosion (cut bank, shoreline, general) ....................... Substantial ....................... Long term—for life of jurisdiction ....................................... Monitor for erosion; stabilize if needed; data recovery as needed General Disturbance .................................................... Moderate ........................... Long-term—for life of jurisdiction ....................................... Monitor; data recovery as needed Agriculture ................................................................... Minor—Moderate ............. Long-term—for life of lease ................................................. Protect or mitigate with fencing, testing, or data recovery Grazing ........................................................................ Minor—Moderate ............. Long term—for life of lease ................................................. Protect or mitigate with fencing, testing, or data recovery Construction ................................................................ Substantial ....................... Short term—up to one year as project progresses ............. Protect or mitigate with fencing, testing, or data recovery Recreation ................................................................... Moderate ........................... Long term—for life of jurisdiction ....................................... Monitor for activity and vandalism; fence as needed Vandalism ................................................................... Moderate ........................... Long term—for life of jurisdiction ....................................... Monitor for activity and vandalism; fence as needed All ................................................................................ Minor—Substantial .......... Short term (1 to 5 years) ...................................................... Prepare research design for cultural resources along the Missouri

River in North Dakota 
54 

10.0 RECOMMENDATIONS

Successfully addressing sedimentation issues within the Missouri River will likely 

require a holistic approach, and recommendations pertaining to multiple resources 

would be a part of that solution. Berger has evaluated a number of approaches to 

addressing impacts throughout this study and makes the following recommendations based on the results (Table 7). 
55 

TABLE 7.—RECOMMENDATIONS FOR ADDRESSING SEDIMENTATION IMPACTS ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Input/Resource Study/Product Timeline Cost Remarks 

Flooding Risks in Bismarck/Mandan Area ....... Tradeoff Analysis of Flood Controls (e.g. development restrictions vs. flow restrictions). Short term ............................... $500,000–$1,000,000 ............. Would require local partner 

Study impacts of sedimentation on flood risks when Lake 

Oahe pool is full.

2 to 3 years to complete ........ $500,000–$1,000,000 ............. Would require a cost-share 

sponsor 

Develop strategies for mitigating ice-affected flooding exacerbated by sediment deposition at the headwaters of Lake 

Oahe.

3 to 5 years to complete ........ $500,000–$1,000,000 ............. Would require a cost-share 

sponsor. Detailed Environmental Assessment (EA), may be an EIS 

Conduct debris/snag removal in the Heart River confluence 

area. This will minimize sediment accumulation in the area and decrease the likelihood of ice-affected flooding.

Short term; Less than 2 years 

to complete.

$100,000–$150,000 for design.$400,000–$1,000,000 for construction.

Would require a cost-share 

sponsor 

Garrison Reach ................................................. Complete cumulative Environmental Impacts Statement (EIS) 

for Garrison Reach.

2 to 3 years to complete ........ $1,000,000–$2,000,000 .......... Would require a cost-share 

sponsor 

Conduct bank stabilization projects ......................................... Short term; Less than 1 year 

to complete.

$300,000–$500,000 per site .. Very difficult without EIS 

Evaluate potential operational changes of the Garrison Dam 

and/or flow modifications.

3 to 5 years to complete ........ $1,000,000–$5,000,000 .......... Controversial; Re-opens master 

manual issues; Possibly outside the scope of title VII 

Fish and Wildlife .............................................. Study to evaluate the needs of multiple species along the 

Missouri River.

.................................................. $250,000–$300,000 (2-year 

study).

Would require a cost-share 

sponsor. Overlap with the BiOp could be complicated 

Study the life-cycle of the pallid sturgeon on the Yellowstone 

River.

.................................................. $200,000–$250,000 (2-year 

study).

This is part of the Missouri 

River Recovery Program 

Cultural Resources ........................................... Prepare a research design for cultural resources along the 

Missouri River. Provide a framework for management and treatment of cultural resources across jurisdictions.

Short term; less than 2 

years.

$200,000–$250,000 ................ Would require a cost-share 

sponsor 

Study to access cultural and historical resource sites to determine if impacts are occurring. Short term; less than 2 years. $250,000–$500,000 ................ Would require a cost-share sponsor 

Watershed Sediment Sources ........................... Study to determine the sediment contribution by source and 

approaches to reduce sediment reaching the river (watersheds and water quality).

3 to 5 years ............................. $500,000–$750,000 ................ BMPs, stream buffers, No-till 

farming, etc; Would require a cost-share partner 

Williston Reach ................................................. Perform hydrological study of sediment impacts to groundwater in the Williston Area. 1 to 2 years ............................. $250,000–$400,000 ................ Would require a cost-share sponsor 
56 

TABLE 7.—RECOMMENDATIONS FOR ADDRESSING SEDIMENTATION IMPACTS ALONG THE MISSOURI RIVER IN NORTH DAKOTA—Continued 

Input/Resource Study/Product Timeline Cost Remarks 

Recreation ......................................................... Dredge the Hazelton boat ramp. ............................................... Short term; Less than 1 year .. $100,000–$200,000 ................ Permits; Redeposit of sediment 

in river 

Study to evaluate any changes in recreational use due to 

sedimentation and drought.

Short term ............................... $250,000–$500,000 ................ Would require a cost-share 

partner. If the study included a survey, it would require Office of Management and Budget (OMB) approval which could impact costs and timing 
57 

APPENDIX A—IDENTIFICATION OF SOURCES AND DEPOSITS AND LOCATIONS OF EROSION

AND SEDIMENTATION

1.0 INTRODUCTION 

The Louis Berger Group Inc. (Berger) was tasked by the U.S. Army Corps of Engineers (USACE) to assess impacts of sedimentation in the Missouri River Basin within the State of North Dakota. This assessment is intended to meet the level of effort 

defined in the Missouri River Protection and Improvement Act. The assessment will 

have two objectives. First, Berger will identify sources and deposit locations of sediment within the Missouri River Basin in the State of North Dakota, using existing 

data and information. Next the team will analyze the potential impacts of sedimentation on important issues and resources including: local, regional and national 

as well as tribal economies; recreation; hydropower generation; fish and wildlife; 

flood control and Indian and non-Indian historical and cultural sites. 

This report focuses on the results of Task 5A—Identification of Sources and Deposit Locations of Erosion and Sedimentation. The assessment included three important steps. First, Berger conducted an extensive literature and data search for all 

possible sources of information that can help determine relevant sites of erosion and 

sedimentation within the Missouri River Basin in North Dakota. This data and information was organized as much as possible into a GIS database that can support 

easy retrieval and interpretation. Second, Berger identified aggradation locations in 

the main stem of the Missouri River based on existing data and information. Third, 

Berger calibrated a planning level tool that can be used to assess and rank different 

sources of sedimentation in the Missouri River. 

The following sections address the results of the task. Section 2.0 describes the 

study area that was evaluated. Section 3.0 provides the results of the literature and 

data search. Section 4.0 discusses the locations of aggradation along the Missouri 

River. Section 5.0 summarizes the sediment source evaluation and Section 6.0 compares the sources of sedimentation with the locations of aggradation evaluated for 

this report. 

2.0 STUDY AREA 

The study area was defined by the USACE to include the watershed of the main 

stem of the Missouri River from the North Dakota—South Dakota border on the 

downstream end to the Montana—North Dakota border on the upstream end. The 

study area includes tributaries of the Missouri River, Lake Sakakawea and Lake 

Oahe. Figure 2–1 provides a map of the study area as defined for this project. 

FIGURE 2–1.—Location of the Study Area 

3.0 LITERATURE AND DATA SEARCH 

The parameters of the project were to evaluate all existing literature and data 

sources that provide information on the potential location for erosion and sedi-
58 

1 Acronym for Hydrologic Unit Code: Every hydrologic unit is defined by a HUC (2 to 12 digits) 

defining the region, sub-region, basin, sub-basin, watershed, and sub-watershed. HUC–8 consists of eight digits and describes the drainage area at sub-basin level. HUC–1 0 consists of ten 

digits and describes the drainage at watershed level. 

mentation in the Missouri River. Because no new data and information was sought, 

Berger focused efforts on an extensive literature and data search. The results are 

discussed in this section. 

3.1 Literature Search 

Berger completed a comprehensive literature search, focusing on identifying and 

acquiring key research papers and documents related to erosion and sedimentation 

in the Missouri River in North Dakota. These sources of information were further 

analyzed and used to develop a series of maps that identify areas and resources that 

may be impacted by sedimentation. These maps will be used as a basis for focusing 

data and information collection efforts in progress for other tasks. 

The literature search included research papers and documents from USACE 

(Omaha District, Northwestern Division at the Reservoir Control Center, Garrison 

District, and Kansas City District), United States Department of Agriculture 

(USDA), Natural Resources Conservation Service (NRCS), Unites States Geological 

Survey (USGS), Journal papers (Hydrological Science, Journal of Hydrology, Journal 

Spatial Hydrology, Environmental Conservation, Water Resources Management, 

Geomorphology), conference proceedings, and other sources. 

A summary of the key documents located to date is outlined in Table 3–1. This 

literature search lead to the identification of locations of erosion and sedimentation 

in the Missouri River as described in Section 5.0. 

3.2 Data Search 

Berger also performed a comprehensive, in-depth data search, focusing on identifying and acquiring a wide range of information. The following summarizes the completed efforts in data acquisition. 

—Retrieved land cover data from the 2001 National Land Cover Data (NLCD) for 

North Dakota. 

—Retrieved and compiled hydrologic data (stream height and flow) and sediment 

data (total suspended sediments) from 15 USGS flow and water quality stations 

located within the study area. The locations of the USGS flow and water quality 

stations are shown in Figure 3–1. 

—Acquired the revised 1997 National Resources Inventory (NRI) database from 

the NRCS. The NRI database is an extensive collection of data such as land 

cover, habitat, and soil erosion from non-Federal lands and water areas within 

48 States in the U.S. (USDA, 2000, 2001). The soil erosion data set was used 

in the planning tool to provide estimates for soil loss per area in the study area. 

—Acquired climatic data from the National Climatic Data Center (NCDC) over 

EarthInfo Inc. and compiled precipitation and temperature data from weather 

stations within the study area. 

—Delineated the entire watershed into HUC–8 1 areas and into HUC–10 areas 

(Figure 3–1). The HUC–10 delineation served as the basis for the thematic map 

discussed in Section 6.0 

The majority of the retrieved data were integrated under a GIS platform for ease 

of analysis and retrieval. Table 3–2 presents the complete inventory of the various 

data types and sources that have been obtained to date. 
59 

TABLE 3–1.—KEY DOCUMENTS RELATED TO EROSION AND SEDIMENTATION IN THE MISSOURI RIVER 

Author Date Title 

Bhattaria, R. and D. Dutta ...................................................................... 2007 ............. Estimation of Soil Erosion and Sediment Yield Using GIS at Catchment Scale Jain, M.K. and U.C. Kothyari .................................................................... 2000 ............. Estimation of Soil Erosion and Sediment Yield Using GIS Jones, D.S., Kowalski, D.G. and R.B. Shaw ............................................. 1996 ............. Calculating Revised Universal Soil Loss Estimates on Department of Defense Lands: A Review of RUSLE factors and U.S. 

Army Land Condition Trend Analysis (LCTA) Data Gaps 

Kothyari, U.C. and M.K. Jain .................................................................... 1997 ............. Sediment yield estimation using GIS Kothyari, U.C., Jain, M.K. and K.G. Ranga Raju ...................................... 2002 ............. Estimation of temporal variation of sediment yield using GIS Mutua, B.M. and A. Klik ........................................................................... 2006 ............. Estimating Spatial Sediment Delivery Ratio on a Large Rural Catchment NRCS ......................................................................................................... 2001 ............. A Guide For Users of 1997 NRI Data Files Ouyang, D. and J. Bartholic ..................................................................... 1997 ............. Predicting Sediment Delivery Ratio in Saginaw Bay Watershed Shields, F.D., Simon, A., and L.J. Steffen ................................................ 2000 ............. Reservoir Effects on Downstream River Channel Migration USACE (Garrison, Omaha, and Cansas City Districts) ............................ 1957 ............. Degradation Below Garrison Dam: Observations in 1954 USACE (Omaha District) ........................................................................... 1980 ............. Verification of Sediment Transport Functions: Missouri River USACE (Omaha District) ........................................................................... 1984 ............. Aggradation and Degradation Aspects of the Missouri River Mainstem Dams USACE (Omaha District) ........................................................................... 1992 ............. Bank Recession USACE (Omaha District) ........................................................................... 1993 ............. Aggradation, Degradation, and Water Quality Conditions: Missouri River Mainstem Reservoir System USACE (Omaha District) ........................................................................... 1993 ............. Downstream Channel and Sediment Trends Study USACE (Omaha District) ........................................................................... June 1993 ..... Lake Oahe Aggradation Study USACE (Northwestern Division, Reservoir Control Center) ....................... 1999 ............. Missouri River Mainstem Reservoirs 1998–1999 Annual Operating Plan USACE (Omaha District) ........................................................................... 2000 ............. Downstream Channel and Sediment Trend Study Update USACE (Omaha District) ........................................................................... Dec. 2001 ..... Missouri River—Fort Peck Dam to Ponca State Park Geomorphological Assessment Related to Bank Stabilization USACE (Omaha District) ........................................................................... 2008 ............. Bank Stabilization Cumulative Impact Analysis Final Technical Report USDA (Glymph, Louis M.) ......................................................................... 1954 ............. Studies of Sediment Yields from Watersheds USDA ......................................................................................................... 1983 ............. National Engineering Handbook, Sedimentation: Sediment Sources, Yields, and Delivery Ratios USGS ......................................................................................................... 1992 ............. Techniques for Estimating Peak Flow Frequency Relations for North Dakota Streams USGS ......................................................................................................... 1995 ............. Transport and Sources of Sediment in the Missouri River between Garrison Dam and the Headwaters of Lake Oahe, North 

Dakota, May 1988 through April 1991 

USGS ......................................................................................................... 2000 ............. Suspended-Sediment Loads from Major Tributaries to the Missouri River between Garrison Dam and Lake Oahe, North 

Dakota, 1954–98 

USGS ......................................................................................................... 2006 ............. Water, Bed-Sediment, and Fish-Tissue Quality within the Standing Rock Sioux Reservation, North Dakota and South Dakota USGS ......................................................................................................... 2006 ............. Water-Quality Characteristics of Montana Streams in a Statewide Monitoring Network, 1999–2003 Walling, D.E. ............................................................................................. 1983 ............. The Sediment Delivery Problem Williams, J.R. ............................................................................................ 1977 ............. Sediment delivery ratios determined with sediment and runoff models Wuebben, J.L. and J.J. Gagnon ................................................................. 1995 ............. Ice jam flooding on the Missouri River near Williston, North Dakota 
60 

FIGURE 3–1.—Watershed Delineation, Weather Station Locations, and USGS 

Stations 

TABLE 3–2.—INVENTORY OF THE ACQUIRED VARIOUS DATA AND SOURCE 

Type Description Source(S) 

Physiographic data ................... Watershed boundary (8-digit and 10-digit HUCs) ..................... USGS, NRCS 

Land use/land cover ................................................................... NLCD 2001 

Soil data (STATSGO/SSURGO) ..................................................... NRCS 

Topographic data ........................................................................ 30m DEM (NED) 

Slopes .......................................................................................... Berger (Based on DEM) 

Stream network and water bodies ............................................. NHD 

River Mile Marker ........................................................................ USACE 

Flow data .................................................................................... USGS 

Stage Height ............................................................................... USGS 

Bluff to bluff ............................................................................... Berger (Based on DEM) 

Areas of Aggradations ................................................................ Berger (From USACE and 

USGS Reports) 

Weather data ............................ Weather Station Location ............................................................ NCDC 

Precipitation ................................................................................ NCDC 

Temperature ................................................................................ NCDC 

Flow data .................................. Daily flow from USGS gaging stations in North Dakota ............ USGS 

Administrative Boundaries ....... Federal Lands (FWS, USACE, BLM, NPS, BIA) ............................ ESRI, Agency Sources 

County/State Boundaries ............................................................ US Census 

Tribal Lands ................................................................................ US Census 

Municipal Areas .......................................................................... USACE 

Recreation ................................. State Park and Recreational Areas ............................................ North Dakota 

Boat Ramps ................................................................................ USACE 

Mitigation/Recovery Site ............................................................. USACE 

Cultural ..................................... Lewis and Clark Campsites ........................................................ USACE 

Cemetery Sites ............................................................................ USACE 

Transportation ........................... Major Highways ........................................................................... US Census 

Railroad ....................................................................................... USACE 
61 

TABLE 3–2.—INVENTORY OF THE ACQUIRED VARIOUS DATA AND SOURCE—Continued 

Type Description Source(S) 

Soil Loss Data .......................... 1997 site-specific revised soil loss data ................................... NRCS 

Water Quality Data ................... Total Suspended Solids Measurements ...................................... USGS 

BLM—Bureau of Land Management 

BIA—Bureau of Indian Affairs 

DEM—Digital Elevation Model 

FWS—Fish and Wildlife Service 

NCDC—National Climatic Data Center 

NHD—National Hydrography Dataset 

NPS—National Park Service 

NRCS—Natural Resources Conservation Service 

USACE—United States Army Corps of Engineers 

USGS—United States Geologic Survey 

3.3 Land Use Distribution 

Sediment can be delivered to the river from point sources located in the watershed 

and it can be carried in the form of non-point source runoff from non-vegetated or 

protected land areas. In addition, sediment can be generated in the river through 

the processes of scour and deposition, which are primarily a function of river flow. 

During periods of high flow, erosion of the river channel occurs. The eroded materials are deposited downstream in areas where the bed material load exceeds the 

transport capacity. As a result, sources of sediment are mainly related to the type 

of land use within the watershed. As such, Berger focused on collecting the most 

recent information on land use for the study area as described below. 

The land use characterization for the study area of the Missouri River was based 

on land cover data from the 2001 National Land Cover Data (NLCD). Figure 3–2 

displays a map of the land uses of watersheds draining into the Missouri River 

within North Dakota. The drainage area of the study area represents the entire Yellowstone River watershed and 17 HUC–8 sub-watersheds. 

Table 3–3 presents the Yellowstone River and the 17 HUC–8 sub-watersheds, as 

shown in Figure 3–2, with their two predominant land uses. A detailed break-down 

of land uses for each watershed is presented in Exhibit A. 

TABLE 3–3.—WATERSHEDS LOCATED IN THE STUDY AREA 

Watershed HUC–8 1

Predominant Land Use 

Category Fraction 

(percent) 

Yellowstone River .................................................................................. ( 2 ) Shrub .................................. 41.2 

Grassland/Herbaceous ....... 31.5 

Lake Sakakawea .................................................................................... 10110101 Cultivated Crops ................ 41.4 

Grassland/Herbaceous ....... 37.5 

Little Muddy River ................................................................................. 10110102 Cultivated Crops ................ 68.4 

Grassland/Herbaceous ....... 21.9 

Upper Little Missouri River ................................................................... 10110201 Grassland/Herbaceous ....... 57.8 

Shrub .................................. 32.0 

Boxelder Creek ....................................................................................... 10110202 Grassland/Herbaceous ....... 64.2 

Shrub .................................. 26.8 

Middle Little Missouri River .................................................................. 10110203 Grassland/Herbaceous ....... 62.9 

Cultivated Crops ................ 14.5 

Beaver Creek ......................................................................................... 10110204 Grassland/Herbaceous ....... 49.9 

Cultivated Crops ................ 31.6 

Lower Little Missouri River .................................................................... 10110205 Grassland/Herbaceous ....... 55.7 

Deciduous Forest ................ 12.5 

Painted Woods-Square Butte ................................................................ 10130101 Grassland/Herbaceous ....... 41.7 

Cultivated Crops ................ 31.9 

Upper Lake Oahe ................................................................................... 10130102 Grassland/Herbaceous ....... 66.3 

Cultivated Crops ................ 16.7 

Apple Creek ........................................................................................... 10130103 Grassland/Herbaceous ....... 56.9 

Cultivated Crops ................ 19.3 

Beaver Creek Oahe ................................................................................ 10130104 Grassland/Herbaceous ....... 57.2 

Cultivated Crops ................ 24.2 

Knife River ............................................................................................. 10130201 Grassland/Herbaceous ....... 57.3 

Cultivated Crops ................ 28.0 

Upper Heart ........................................................................................... 10130202 Cultivated Crops ................ 42.6 

Grassland/Herbaceous ....... 40.1 
62 

TABLE 3–3.—WATERSHEDS LOCATED IN THE STUDY AREA—Continued 

Watershed HUC–8 1

Predominant Land Use 

Category Fraction 

(percent) 

Lower Heart River .................................................................................. 10130203 Grassland/Herbaceous ....... 51.3 

Cultivated Crops ................ 33.5 

Upper Cannonball River ........................................................................ 10130204 Cultivated Crops ................ 48.2 

Grassland/Herbaceous ....... 32.9 

Cedar Creek ........................................................................................... 10130205 Grassland/Herbaceous ....... 42.5 

Cultivated Crops ................ 38.1 

Lower Cannonball River ........................................................................ 10130206 Grassland/Herbaceous ....... 77.0 

Cultivated Crops ................ 15.3 

1 HUC–8 = Hydraulic Unit Code describing the drainage area at sub-basin level. 

2 This includes the entire Yellowstone River watershed. 

The overall distribution of land uses in the study area by land area and percentage is presented in Table 3–3 and a brief description of land use classifications are 

presented in Table 3–4. Overall, grassland represents the dominant land use type 

(43.1 percent) followed by shrub and agriculture (both 21 percent). Cultivated crops 

showed greatest fraction in agriculture lands (16.6 percent). Forested land comprises 

8.3 percent of the land cover in the study area. The smallest percentage of land 

cover is for perennial ice/snow that is only part of the land use distribution in the 

Yellowstone River (0.04 percent). 

TABLE 3–4.—LAND USE CATEGORY AND DISTRIBUTION WITHIN THE STUDY AREA 

Land Use Category NLCD Land Use Type Hectare 

Fraction of Watershed’s Land Use Area 

(percent) 

Water/Wetland .............................................. Open Water .................................................. 423,736 2.20 

Woody Wetlands ........................................... 189,262 0.98 

Emergent Herbaceous Wetlands .................. 205,991 1.07 

Subtotal .......................................... ...................................................................... 818,989 4.25 

Developed ..................................................... Developed, Low Intensity ............................. 47,078 0.24 

Developed, Medium Intensity ....................... 7,105 0.04 

Developed, High Intensity ............................ 1,275 0.01 

Subtotal .......................................... ...................................................................... 55,457 0.29 

Agriculture ................................................... Pasture/Hay .................................................. 740,443 3.84 

Cultivated Crops .......................................... 3,203,883 16.62 

Subtotal .......................................... ...................................................................... 3,944,326 20.46 

Grassland (Prairie) ...................................... Grassland/Herbaceous ................................. 8,301,537 43.07 

Forest ........................................................... Deciduous Forest ......................................... 177,801 0.92 

Evergreen Forest .......................................... 1,412,006 7.33 

Mixed Forest ................................................. 17,412 0.09 

Subtotal .......................................... ...................................................................... 1,607,220 8.34 

Shrub ........................................................... Shrub ........................................................... 4,044,607 20.98 

Other ............................................................ Developed, Open Space ............................... 316,051 1.64 

Barren Land (Rock/Sand/Clay) .................... 178,444 0.93 

Perennial Ice/Snow ...................................... 8,417 0.04 

Subtotal .......................................... ...................................................................... 502,911 2.61 

Total ............................................... ...................................................................... 19,275,047 100.00 
63 

FIGURE 3–2.—Land Use Distribution of the Study Area in the Missouri River (ND) 

TABLE 3–5.—DESCRIPTIONS OF 2001 NLCD LAND USE TYPES 

Land Use Type Description 

Open Water ...................................... All areas of open water, generally with less than 25 percent cover of vegetation or 

soil. 

Woody Wetlands ............................... Areas where forest or shrub land vegetation accounts for greater than 20 percent of 

vegetative cover and the soil or substrate is periodically saturated with or covered 

with water. 

Emergent Herbaceous Wetlands ...... Areas where perennial herbaceous vegetation accounts for 75–100 percent of the 

cover and the soil or substrate is periodically saturated with or covered with 

water. 

Developed, Open Space ................... Includes areas with a mixture of some constructed materials, but mostly vegetation 

in the form of lawn grasses. Impervious surfaces account for less than 20 percent 

of total cover. These areas most commonly include large-lot single-family housing 

units, parks, golf courses, and vegetation planted in developed settings for recreation, erosion control, or aesthetic purposes. 

Developed, Low Intensity ................. Includes areas with a mixture of constructed materials and vegetation. Impervious 

surfaces account for 20–49 percent of total cover. These areas most commonly include single-family housing units. 

Developed, Medium Intensity ........... Includes areas with a mixture of constructed materials and vegetation. Impervious 

surfaces account for 50–79 percent of the total cover. These areas most commonly 

include single-family housing units. 

Developed, High Intensity ................ Includes highly developed areas where people reside or work in high numbers. Examples include apartment complexes, row houses and commercial/industrial. Total 

cover is 80–100 percent impervious surfaces. 

Pasture/Hay ...................................... Areas of grasses, legumes, or grass-legume mixtures planted for livestock grazing or 

the production of seed or hay crops, typically on a perennial cycle. Pasture/hay 

vegetation accounts for greater than 20 percent of total vegetation. 

Cultivated Crops .............................. Areas used for the production of annual crops, such as corn, soybeans, vegetables, 

tobacco, and cotton, and also perennial woody crops such as orchards and vineyards. Crop vegetation accounts for greater than 20 percent of total vegetation. 

This class also includes all land being actively tilled. 

Grassland ......................................... Areas dominated by upland grasses and forbs. In rare cases, herbaceous cover is 

less than 25 percent, but exceeds the combined cover of the woody species 

present. These areas are not subject to intensive management, but they are often 

utilized for grazing. 
64 

TABLE 3–5.—DESCRIPTIONS OF 2001 NLCD LAND USE TYPES—Continued 

Land Use Type Description 

Deciduous Forest .............................. Areas dominated by trees generally greater than 5 meters tall, and greater than 20 

percent of total vegetation cover. More than 75 percent of the tree species shed 

foliage simultaneously in response to seasonal change. 

Evergreen Forest .............................. Areas dominated by trees generally greater than 5 meters tall, and greater than 20 

percent of total vegetation cover. More than 75 percent of the tree species maintain their leaves all year. Canopy is never without green foliage. 

Mixed Forest ..................................... Areas dominated by trees generally greater than 5 meters tall, and greater than 20 

percent of total vegetation cover. Neither deciduous nor evergreen species are 

greater than 75 percent of total tree cover. 

Shrub ................................................ Areas characterized by natural or semi-natural woody vegetation with aerial stems, 

generally less than 6 meters tall, with individuals or clumps not touching to interlocking. Both evergreen and deciduous species of true shrubs, young trees, and 

trees or shrubs that are small or stunted because of environmental conditions are 

included. 

Barren Land ..................................... Barren areas of bedrock, desert pavement, scarps, talus, slides, volcanic material, 

glacial debris, sand dunes, strip mines, gravel pits and other accumulations of 

earthen material. Generally, vegetation accounts for less than 15 percent of total 

cover. 

Source.—National Land Cover Data (NLCD) (http://www.epa.gov/mrlc/definitions.html). 

3.4 Flow and Sediment Data 

Environmental monitoring efforts in the study area include flow and total suspended solid (TSS) measurements at three monitoring stations on the mainstem of 

the Missouri River and six monitoring stations at tributaries flowing into the Missouri River. Additionally, monitoring stations located at the Montana/North Dakota 

border (USGS 06185500) and the Yellowstone River in Montana (USGS 06329500) 

were included as boundary stations. Monitoring efforts presented in this section 

were conducted by the USGS. 

Figure 3–1 shows the location of the USGS stations. Table 3–6 presents an inventory of available flow and TSS data at USGS monitoring stations in the study area 

including the data range, number of samples, minimum, maximum, standard deviation, and average of the data type at each USGS station. Overall, historic and recent flow measurements were available for the majority of the stations. On average, 

the Yellowstone River delivered the largest amount of flow to the Missouri River 

within North Dakota followed closely by the amount of flow delivered from Montana. The remaining major tributaries discharging into the Missouri River within 

North Dakota had a relatively small impact on the flow budget in the Missouri 

River. As for TSS measurements, data were limited and no current measurements 

have been taken. Nonetheless, for comparison reason, the available TSS concentrations were graphed with the corresponding flow in Figures A–1 through A–7 of Exhibit A. In general, spikes of TSS levels were a direct response to high flow events. 
65 

TABLE 3–6.—INVENTORY OF FLOW (m3/sec) AND TOTAL SUSPENDED SOLIDS (mg/L) MONITORING STATIONS IN THE STUDY AREA 

USGS Station 

Number River/Station Name Data Type Data Range 1 Number of Samples Min Max Mean STDEV 

Missouri River 

6185500 Missouri River near Culbertson, MT ................................ Flow ........... 07/01/1941–12/31/1951 04/01/1958-present ................ 22,020 16.3 1,959.5 281.0 144.0 

TSS ............ 10/01/1971–09/30/1976 ................................................. 1,826 30.0 2,900.0 365.1 350.7 

06330000 Missouri River, Williston, ND ........................................... Flow ........... 10/01/1928–07/31/1965 ................................................. 13,453 37.4 5,097.0 577.8 422.8 06338490 Missouri River, Garrison Dam ......................................... Flow ........... 10/01/1969–09/30/2007 ................................................. 13,876 116.1 1,846.3 606.3 224.7 06342500 Missouri River, Bismarck, ND ......................................... Flow ........... 10/01/1927-present ......................................................... 29,323 51.0 10,279.0 628.7 368.7 

TSS ............ 10/01/1971–09/30/1981 ................................................. 3,653 14.0 2,800.0 173.7 180.1 

Tributaries 

06329500 Yellowstone River near Sidney MT .................................. Flow ........... 10/01/1910–12/31/1931 10/01/1933-present ................ 34,888 16.1 4,021.0 349.4 358.7 

TSS ............ 06/18/1965; 10/03/1971–05/28/08 ................................ 426 10.0 15,500.0 900.0 1596.0 

06340500 Knife River, at Hazen, ND ............................................... Flow ........... 04/01/1929-present ......................................................... 28,798 .................. 634.3 4.3 19.6 

TSS ............ 03/08/1946–07/31/1946 04/23/1948–09/30/1948 ........ 292 29.0 6,900.0 441.4 882.3 

06341410 Turtle Creek, above Washburn ........................................ Flow ........... 10/01/1986–09/30/2003 ................................................. 6,209 .................. 21.7 0.4 0.9 06342260 Square Butte Creek, below Center, ND ........................... Flow ........... 06/01/1965-present ......................................................... 15,675 .................. 75.6 0.3 2.5 06342450 Burnt Creek, near Bismarck, ND ..................................... Flow ........... 10/01/1967-present ......................................................... 11,656 .................. 110.4 0.3 2.1 06349000 Heart River, near Mandan, ND ........................................ Flow ........... 04/01/1924-present ......................................................... 27,822 .................. 804.2 7.2 27.4 

TSS ............ 10/01/1971–09/30/1976 ................................................. 1,826 1.0 3,460.0 124.1 358.7 

06349500 Apple Creek, near Menoken, ND ...................................... Flow ........... 03/01/1905-present ......................................................... 22,891 .................. 158.3 1.2 4.9 

1 Data were retrieved from begin of record until June 15, 2008; Flow were continuous measured and TSS instantaneous. 

TSS—Total Suspended Solids 
66 

4.0 IDENTIFICATION OF AGGRADATION LOCATIONS IN THE MAINSTEM OF 

THE MISSOURI RIVER 

Prior to the identification of sources of erosion and sedimentation (described in 

Section 5), Berger conducted an analysis of aggradation areas within the main stem 

of the Missouri River using information from three available key documents. Sediment deposit sites located upstream from Garrison Dam were identified based on 

information from the Aggradation, Degradation, and Water Quality Conditions report by USACE (1993). Sediment deposit sites located between the Garrison Dam 

and the city of Bismarck were identified based on information from the Missouri 

River—Fort Peck Dam to Ponca State Park Geomorphological Assessment Related 

to Bank Stabilization report by USACE (December 2001). Sediment deposit sites located between the city of Bismarck and the downstream boundary of this study (Figure 3–1) were identified based on information from the Lake Oahe Aggradation 

Study by USACE (June 1993). However, these reports were used to identify 

aggradation areas only in longitudinal direction. As a result, the latitudinal extent 

of the aggradation areas was randomly defined between bluff to bluff of the Missouri 

River. The aggradation areas were classified in low, moderate, and high in order to 

show qualitatively the magnitude of aggradation (the classification was based on 

narrative and numeric description of the magnitude of aggradation reported in the 

above quoted literature). 

Sediment Aggregation Between ND–MT State Line and Garrison Dam 

The USACE (1993) report compiled a record of available sediment-related data 

and information that were collected at least 30 years ago (between 1946 and 1989) 

by the USACE (Omaha District) and USGS on the Missouri River in Montana, 

North Dakota, South Dakota, and Nebraska. The report also provided an evaluation 

of changes in channel geometry (channel width, average bed profile, thalweg profile, 

and cross-sectional area) in order to analyze reservoir volume, bed material gradation, stream bank erosion, and tailwater trends in terms of aggradation and degradation. 

Specifically, the thalweg profiles and the average bed profiles developed between 

the North Dakota and Montana State line for 4 representative years (1956, 1964, 

1978, and 1987) presented in the USACE report were used by Berger to locate and 

estimate qualitatively aggradation sites in this area. Based on this analysis, the 

largest continuous area of sediment aggradation were found in the upstream ends 

of Lake Sakakawea extending approximately over 94 miles between river mile 1564 

(approximately 22 miles downstream from the Yellowstone River) and river mile 

1470 (approximately 4 miles downstream from Clarks Creek) (Figures 4–1 and 4– 

2). The highest level of aggradation in this area were located between river mile 

1534 and river mile 1521 shown in red in Figure 4–1. It should be noted that the 

presented location of the aggradation areas needs to be verified with more current 

measurements. 

Sediment Aggradation Between Garrison Dam and the City of Bismarck 

The USACE (Dec. 2001) report evaluated the potential impacts of bank stabilization on the morphologic processes in the Missouri River. The report analyzes four 

open stretches on the main stem of the Missouri River (Fort Peck to vicinity of Yellowstone River, Garrison Dam to Lake Oahe, Fort Randall Dam to the Niobrara 

River, and Gavins Point Dam to Ponca). The analysis is based on an extensive field 

investigation and data collection for sediment from banks, bars, islands, and tributaries, and includes the establishment of relationships between channel width and 

bars and islands, bar and island density analysis, sediment gradation analysis, bank 

erosion analysis, and sediment budget. 

Specifically, the calculated net sediment transport presented in the USACE (Dec. 

2001) for the Garrison Reach was used by Berger to locate and estimate qualitatively aggradation sites in this area. The reported net sediment transport volumes 

were calculated for six geomorphic reaches and were based on estimated volumes 

for erosion and deposition at banks and beds between 1976 and 1998. Overall, the 

Garrison reach is dominated by erosion with stream bed erosion playing the major 

role. The largest erosion was found in the upper section of the Garrison reach between Garrison Dam and river mile 1363. Downstream from this section between 

river mile 1362 and 1363 (geomorphic reach GR3), erosion decreased considerably 

which led to the only aggradation area located within the Garrison Reach. Figure 

4–3 depicts the location of this aggregation area. The erosion in the remaining 

downstream section between river mile 1352 and 1315 increased again and reached 

a dynamic equilibrium in the last 24 miles (river mile 1339 to 1315) of the Garrison 

Reach. 
67 

Sediment Aggradation Between the City of Bismarck and the Downstream Boundary 

of This Study (Upper end of Lake Oahe) 

The USACE (June 1993) compiled information on morphologic conditions and 

trends for Lake Oahe using historic survey data (profiles of the aggradation ranges, 

bed and suspended sediment data, density of sediment deposits, pool elevation 

records, capacity and sediment depletion data, and shoreline erosion information) 

collected during eight surveys between 1958 and 1989. 

Specifically, the profiles for average bed elevation profiles, thalweg elevation, and 

average depth of sediment deposit presented in the USACE report were used by 

Berger to locate and estimate qualitatively aggradation sites in this area. Except for 

an approximately 10 mile stretch downstream of the city of Bismarck, aggradation 

areas were identified along the entire section (Figures 4–3 and 4–4). High amount 

of aggradation were found in four relatively small stretches of approximately 5 miles 

long located at approximately 20 miles downstream from the city of Bismarck and 

upstream and downstream of the confluence with the Grand River (RM 1190— 

1205). A stretch of 31 miles located between RM 1248 and 1217 showed the largest 

extent of medium aggradation (Figure 4–4). 
68 

FIGURE 4–1.—Aggradations Area Map—Lake Sakakawea upstream from Garrison 

Dam through Williston, ND 
69 

FIGURE 4–2.—Aggradations Area Map—Lake Sakakawea upstream from Garrison 

Dam through Ft. Berthold Indian Reservation 
70 

FIGURE 4–3.—Aggradations Area Map—Mainstem between Garrison Dam and RM 

1279 
71 

FIGURE 4–4.—Aggradations Area Map—Mainstem between RM 1279 and 1180 

5.0 SEDIMENT SOURCE ASSESSMENT 

Berger conducted an assessment of potential sediment sources for the mainstem 

Missouri River in North Dakota. The purpose of this assessment is to estimate ap-
72 

proximate sediment loads of each potential source delivered to the mainstem Missouri River in North Dakota and approximate sediment loads produced within the 

mainstem Missouri River in North Dakota (instream erosion loads from bed and 

banks). Potential sediment sources are delivered from Missouri River in Montana, 

the Yellowstone River watershed (largest watershed draining into the Missouri 

River within North Dakota), from the remaining watersheds in North Dakota draining into the Missouri River, and produced within the area between Garrison Dam 

and the city of Bismarck of the Missouri River. The delivered sediment loads from 

Montana and from the Yellowstone River were obtained from sediment load estimates by USACE. The delivered sediment loads from the remaining watersheds 

within North Dakota were estimated using the planning-level tool Generalized Watershed Loadings Functions (GWLF). The instream erosion loads were estimated 

using USGS gaging data and the estimates from GWLF. 

5.1 Delivered Sediment Load From Montana and the Yellowstone River 

Based on Wuebben and Gagnon (1995), the USACE in 1978 estimated an annual 

long-term sediment load for Missouri River at Culbertson, Montana (USGS gage 

number 06185500, located approximately 20 miles upstream from the Montana— 

North Dakota border) of approximately 13.5 million tons and for the Yellowstone 

River at Sidney, Montana (USGS gage number 06329500, located approximately 20 

miles upstream from the confluence with the Missouri River) of approximately 41.5 

million tons. Both sediment loads are delivered into Lake Sakakawea. However, as 

mentioned in Wueben and Gagnon (1995), based on a preliminary study by the 

USGS, these loads may have been overestimated by 30-percent. The USACE (1993a) 

estimated that the gross storage loss for all of Lake Sakakawea since closure of the 

dam in 1953 and the survey date in 1988 was 907,000 acre-feet or 25,900 acre-feet/ 

year. Using a bulk density of 1.4 g/cm3, based on values provided by Geiger (1963) 

for sand and silt, this volume translates into a sediment supply of 45 million tons/ 

year. This volume is similar to the volume discussed above in Wuebben and Gagnon 

(1995), after allowing for a 30 percent reduction as suggested. Therefore, using this 

30-percent reduction, the approximate annual delivered sediment load from the Missouri River at Culbertson, Montana, is 9.5 million tons and from the Yellowstone 

River at Sidney, Montana, 29.1 million tons. 

5.2 Delivered Sediments From the Remaining Watersheds Within the Study Area 

Berger evaluated sediment sources for the remaining watersheds draining into 

the Missouri River in North Dakota using a planning level tool. The remaining watersheds included the HUC–8 watersheds Lake Sakakawea, Little Muddy River, 

Upper Little Missouri River, Boxelder Creek, Middle Little Missouri River, Beaver 

Creek, Lower Little Missouri River, Painted Woods-Square Butte, Upper Lake Oahe, 

Apple Creek, Beaver Creek Oahe, Knife River, Upper Heart, Lower Heart River, 

Upper Cannonball River, Cedar Creek, and Lower Cannonball River. The planninglevel tool is the Generalized Watershed Loadings Functions (GWLF). It is a timevariable simulation model that simulates hydrology and land-based sediment loadings on a watershed basis. The objective was to combine the data collected for these 

watersheds and to assess and rank the land-based loads of sediments. 

The following outlines the overall procedure used to assess the sources of erosion 

in the remaining watersheds within the study area: 

—The watershed was divided into HUC–10 segments (Figure 3–1). These sub-watersheds served as the basis for developing the erosion sources thematic map 

which shows the land-based sediment loads for each sub-watershed. 

—The planning tool was applied to the Knife River watershed to estimate the delivered land based sediment unit-loads (tons per hectare) to the Missouri River. 

The Knife River watershed served as a prototype to verify the hydrology and 

generate the reference land-based sediment loads by land use category. As a result, the planning tool was validated for hydrology and sediment loads. 

—The reference land-based delivered sediment unit-loads, specific to the Knife 

River; serve as a basis to develop the unit-loads in each of the sub-watersheds. 

The Knife River unit-loads were adjusted using the following HUC10 specific 

factors: 

—Land use distribution in each of the HUC10 watersheds (Exhibit A) 

—Soil erodibility (K factor) 

—Field slope length and steepness (LS factor) 

—Land cover management factor (C factor) 

—Conservation practice factor (P factor) 

—Sediment delivery ratios based on drainage area and total delivered sediment 

load 
73 

5.2.1 Description of the Planning Tool—GWLF 

The GWLF planning tool is a time variable model that simulates hydrology and 

sediment loadings on a watershed basis. Observed daily precipitation data is required in GWLF as the basis for water budget calculations. Surface runoff, 

evapotranspiration and groundwater flows are calculated based on user specified parameters. Stream flow is the sum of surface runoff and groundwater discharge and 

was computed using the Soil Conservation Service’s Curve Number Equation. Curve 

numbers are a function of soils and land use type. Evapotranspiration is computed 

based on the method described by Hamon (1961) and is dependent upon temperature, daylight hours, saturated water vapor pressure, and a cover coefficient. 

Groundwater discharge to the stream was calculated using a lumped parameter for 

unsaturated and shallow saturated water zones. Infiltration to the unsaturated zone 

occurs when precipitation exceeds surface runoff and evapotranspiration. Percolation to the shallow saturated zone occurs when the unsaturated zone capacity is exceeded. The shallow saturated zone is modeled as a linear reservoir to calculate 

groundwater discharge. In addition, the model allows for seepage to a deep saturated zone. 

Erosion and sediment loading is a function of the land source areas present in 

the watershed. Multiple source areas may be defined based on land use type, the 

underlying soils type, and the management practices applied to the lands. Sediment 

loads from each source area are summed to obtain a watershed total. The Universal 

Soil Loss Equation (USLE) is used to compute erosion for each source area and a 

sediment delivery ratio is applied to determine the sediment loadings to the stream 

(Wischmeier and Smith, 1978), and is expressed as: 

A = R*K*LS*C*P 

Where: 

A = Average annual soil loss in tons per hectare per year 

R = Rainfall/runoff erosivity 

K = Soil erodibility 

LS = Field slope length and steepness 

C = Cover/management factor 

P = Conservation practice factor. 

The R factor is an expression of the erosivity of rainfall and runoff in the area 

of interest; the R factor increases as the amount and intensity of rainfall increases. 

The K factor represents the inherent erodibility of the soils in the area of interest 

under standard experimental conditions. The K factor is expressed as a function of 

the particle-size distribution, organic-matter content, structure, and permeability of 

the soils. The LS factor represents the effect of topography, specifically field slope 

length and steepness, on rates of soil loss at a particular site. The LS factor increases with field slope length and steepness due to the resulting accumulation and 

acceleration of surface runoff as it flows down slope. The C factor represents the 

effects of surface cover and roughness, soil biomass, and soil-disturbing activities on 

rates of soil loss at the area of interest. The C factor decreases as surface cover and 

soil biomass increase. The P factor represents the effects of supporting conservation 

practices, such as contouring, buffer strips, and terracing, on soil loss at the area 

of interest. 

5.2.2 Application of the Planning Tool to the Knife River 

This section presents and describes the setup and calibration of the GWLF planning tool and the sediment loading estimates generated for the Knife River. The tool 

was set up and validated for hydrology and sediment by comparing model output 

to observed stream flow data and published sediment loading data. 

5.2.2.1 Model Set-Up 

The GWLF planning tool requires two input files: a weather input file (Weather.dat) and a transport input file (Transport.dat). The weather input file requires 

daily precipitation data expressed in centimeters and daily temperature data expressed in degrees Celsius. The transport input file requires specification of input 

parameters relating to hydrology, erosion, and sediment yield. Runoff curve numbers and USLE erosion factors are specified as an average value for a given source 

area. The existing and projected land cover classifications present in the study area 

(Section 4) were used to define model source areas. A total of 16 source areas were 

defined in modeling the land cover conditions in the study area. As necessary, GIS 

analyses were employed to obtain area-weighted parameter values for each given 

source area. 
74 

Runoff curve numbers were developed for each model source area in the study 

area based on values published in the NRCS Technical Release 55 (NRCS, 1986). 

STATSGO soils GIS coverages were analyzed to determine the dominant soil hydrologic groups for each model source area. Evapotranspiration cover coefficients were 

developed based on values provided in the GWLF manual (Haith et al., 1992) for 

each model source area. Average watershed monthly evapotranspiration cover coefficients were computed based on an area-weighted method. Initialization of groundwater hydrology and other parameters were set to default values recommended in 

the GWLF manual. 

USLE factors for soil erodibility (K), length-slope (LS), cover and management (C), 

and supporting practice (P) were derived from multiple sources based on data availability. KLSCP factors were obtained from the revised 1997 National Resources Inventory (NRI) database provided by the NRCS. Otherwise, average K, LS, C, and 

P values for model source areas were determined based on GIS analysis of soils and 

topographic coverages, and literature review. The rainfall erosivity coefficient was 

determined from values given in the GWLF manual. The sediment delivery ratio 

was computed directly in the GWLF model interface. 

Developed lands include impervious surfaces that are not subject to soil erosion. 

Therefore, sediment loads from developed lands were not modeled using the USLE. 

Instead, sediment loads from developed lands were computed based on typical loading rates from developed lands (Horner et al., 1994). 

5.2.2.2 Hydrology Calibration in the Knife River Watershed 

GWLF was originally developed as a planning tool for estimating nutrient and 

sediment loadings on a watershed basis. Designers of the model intended for it to 

be implemented without calibration. Nonetheless, comparisons were made between 

predicted and observed stream flow collected in the study area to ensure the general 

validity of the model. 

Daily stream flow data were available at one USGS station (06340500) located in 

the study area (Figure 3–1). The groundwater seepage coefficient, base flow recession coefficient, and unsaturated zone available water capacity were adjusted using 

an iterative approach in order to obtain a best fit with observed data. 

Results of the hydrology verification are presented in Figures 5–1 and 5–2. Figure 

5–1 depicts the monthly observed and simulated flows and Figure 5–2 shows the 

stream flow verification statistics. Total flow volume was under-predicted by approximately 13 percent. The GWLF model predicted fairly well the observed flow in 

the Knife River indicated by the robustness of the regression with an R-square of 

0.87. 

FIGURE 5–1.—Hydrology Verification for the Knife River—Observed and Simulated 

Flow 
75 

FIGURE 5–2.—Hydrology Verification for the Knife River—Regression between 

Observed and Simulated Flows 

5.2.2.3 Sediment Loads Verification in the Knife River Watershed 

The objective of the sediment verification was to insure that the sediment loads 

(erosion rates or edge of stream loads) were within acceptable published values. As 

a guideline, published literature values of expected erosion rates (Donigian, 2003) 

were used. Table 5–1 depicts the results of the simulated erosion rates in the Knife 

River watershed as they compared to the published values. 

TABLE 5–1.—SIMULATED EROSION RATES BY LAND COVER TYPE IN THE KNIFE RIVER 

WATERSHED 

Land Use Type Published Values 

(tons/ha) 

Simulated Erosion Rates (tons/ha) 

MEAN STDEV MIN MAX 

Mixed Forest ............................................................................................. 0.1–0.9 0.29 0.16 0.11 0.51 

Grassland/Herbaceous ............................................................................. 0.35–1.9 0.82 0.46 0.33 1.47 

Pasture/Hay .............................................................................................. 0.7–3.8 1.53 0.86 0.61 2.73 

Cultivated Crop 1 ..................................................................................... 1.6–12.3 3.67 2.07 1.45 6.55 

Barren Land ............................................................................................. > 15.0 5.05 2.85 2.00 9.00 

Developed, Low intensity ......................................................................... 0.4–2.2 0.27 0.15 0.11 0.49 

Developed, Med Intensity ......................................................................... 0.4–2.2 0.32 0.18 0.13 0.57 

Developed, High Intensity ........................................................................ 0.4–2.2 0.38 0.22 0.15 0.68 

Developed, Open Space ........................................................................... 0.4–2.2 0.40 0.22 0.16 0.71 

1 Average sediment loads from conventional and low-till land uses. 

The typical erosion rates presented in Table 5–1 were used as verification guidelines to insure that the simulated erosion rates were within acceptable published 

values. These sediment loads from the Knife River serve as the basis to estimate 

the sediment loads from the remaining watersheds. 

5.2.3 Sediment Load Assessment for the Remaining Sub-Watersheds 

The reference land-based delivered sediment unit-loads presented in the previous 

section served as a basis to develop the unit-loads in each of the sub-watersheds. 

In the first step, the sediment unit-loads were applied to the land use distribution 

in each of the sub-watersheds. Then the estimated sediment loads were adjusted 

using the specific K, LS, C, and P factors of the prototype watershed (Knife River) 

and each sub-watershed. This initial adjustment accounted for the differences between the Knife River watershed and each sub-watershed in terms of the USLE factors including: soil erodibility (K factor), field slope length and steepness (LS factor), 
76 

land cover management factor (C factor), and the conservation practice factor (P factor) The USLE factors were obtained from the revised 1997 NRI database. 

The derived sediment loads from each sub-watershed were then adjusted to derive 

the sediment loads delivered to the Missouri River. Sediment delivery ratios were 

estimated for each sub-watershed based on the size of the drainage area using a 

method published by McCuen (1998) for Midwestern watersheds: 

SDL = 64.6 * A¥0.2775(100 ≤ A ≤ 1000mi2) 

SDL = Sediment Delivery ratio (%) 

A = Drainage Area (mi2) 

The estimated land-based sediment loads delivered to the Missouri River in North 

Dakota from each of the sub-watersheds were used to develop a thematic map using 

GIS. Figure 5–3 shows the thematic map of the land-based delivered sediments to 

the main stem of the Missouri River from each sub-watershed. The results revealed 

that the largest portion of the delivered sediment loads originated from the northern 

and center sections of the study area. These areas also contained the largest percentage of land cover devoted to cultivated crops in the study area that is prone to 

soil erosion (Figure 3–2). The calculated total delivered sediment load was then used 

to rank each of the sub-watersheds (HUC08) based on loads (Table 5–2). As a result 

of this analysis, the highest delivered sediment load to the Missouri River originated 

from the Lake Sakakawea watershed that accounts for approximately 29-percent of 

the total delivered land based sediment load. 

TABLE 5–2.—DELIVERED SEDIMENT LOAD TO THE MISSOURI RIVER FROM EACH WATERSHED 

(HUC08) 

Watershed HUC08 

Sediment Load delivered to the Missouri River 

metric tons/year 

Fraction of the 

total delivered 

load (percent) 

Lake Sakakawea ....................................................................................... 10110101 ........ 496,447 28.7 

Painted Woods—Square Butte ................................................................ 10130101 ........ 159,527 9.2 

Knife River ................................................................................................ 10130201 ........ 150,124 8.7 

Upper Cannonball River ........................................................................... 10130204 ........ 126,027 7.3 

Upper Heart .............................................................................................. 10130202 ........ 105,946 6.1 

Lower Heart River ..................................................................................... 10130203 ........ 102,731 5.90 

Upper Lake Oahe ...................................................................................... 10130102 ........ 94,924 5.5

Little Muddy River .................................................................................... 10110102 ........ 91,445 5.3 

Middle Little Missouri River ..................................................................... 10110203 ........ 88,971 5.1 

Cedar Creek .............................................................................................. 10130205 ........ 74,852 4.3 

Apple Creek .............................................................................................. 10130103 ........ 53,657 3.1 

Upper Little Missouri River ...................................................................... 10110201 ........ 49,194 2.8 

Beaver Creek ............................................................................................ 10110204 ........ 38,660 2.2 

Upper Cannonball River ........................................................................... 10130204 ........ 33,356 1.9 

Beaver Oahe Creek ................................................................................... 10130104 ........ 32,153 1.9 

Boxelder Creek .......................................................................................... 10110202 ........ 25,350 1.5 

Lower Little Missouri River ...................................................................... 10110205 ........ 7,280 0.4 

Total delivered land based load ................................................ .......................... 1,730,644 100.0 

5.3 Produced Instream Erosion in the Mainstem of the Missouri River Between Garrison Dam and the City of Bismarck 

Based on the analysis in section 4 of this report and additional studies by USACE 

(2008) and USGS (1995), the mainstem reach between Garrison Dam and the city 

of Bismarck is the only segment in the mainstem of the Missouri River of North 

Dakota in which instream erosion dominates. The total instream erosion load for 

this reach was estimated by subtracting the total annual sediment load at the 

USGS Bismarck gaging station (USGS 06342500) from the sediment load delivered 

by sub-watersheds that drain into the Missouri River between Garrison Dam and 

the city of Bismarck; the sediment load delivered from Garrison Dam was deemed 

to be insignificant. The total annual sediment load was estimated using all available 

flow and TSS measurements (1971–1981) at USGS 06342500 (Table 3–6) and a 10 

percent adjustment to account for bedload (USGS, 1995). The total sediment load 
77 

delivered from the sub-watersheds draining into the Missouri River between Garrison Dam and the city of Bismarck was estimated based on estimates provided in 

Table 5–2. This analysis resulted in a total instream erosion load of 4.7 million tons/ 

year and accounts for 90 percent of the total sediment load produced between Garrison Dam and the City of Bismarck. 

5.4 Summary of Sediment Loads in the Missouri River Within North Dakota 

Based on the sediment load assessment conducted in Section 5.1, 5.2, and 5.3, the 

Yellowstone River and the Missouri River in Montana delivered the largest fraction 

of sediment loads to the main stem Missouri River in North Dakota. The Yellowstone River and the Missouri River in Montana accounted for more than 86 percent 

of the total delivered load whereas the watersheds within the study area (not including the Yellowstone River watershed) accounted only for approximately 4 percent of the total delivered load in North Dakota. Sediment load from instream erosion within the Missouri River accounted for more than 10 percent. Table 5–3 summarizes the sediment loads and their fractions. 

TABLE 5–3.—SEDIMENT LOADS AND THEIR FRACTIONS IN THE MISSOURI RIVER, ND 

Source 

Estimated Sediment 

Load of the mainstem 

of the Missouri River 

within North Dakota 

(million tons/year) 

Fraction of Total Delivered Sediment Load (percent) 

Yellowstone River 1 .................................................................................................. 29.1 64.7 

Missouri River from Montana 2 ............................................................................... 9.5 21.1 

Watersheds within the Study Area 3 ....................................................................... 1.7 3.8 

Instream Erosion within the Garrison Reach 4 ....................................................... 4.7 10.4 

Total 5 ........................................................................................................ 45.0 100.0 

1 Based on estimated sediment loads by USACE at USGS station 06185500 (Missouri River at Culbertson, Montana) and reduction of 30

percent. 2 Based on estimated sediment loads by USACE at USGS station 06329500 (Yellowstone River at Sidney, Montana) and reduction of 30 per- cent. 3 Based on 5 year average sediment load using GWLF; Includes all watersheds draining into the Missouri River in North Dakota except for 

the Yellowstone River. 4 Based on the difference between the total annual sediment load at USGS 06342500 and the total delivered sediment load of the four sub-watersheds draining between Garrison Dam and the city of Bismarck. 5 Sum of delivered sediment load to the mainstem of the Missouri River within North Dakota and produced sediment within the Garrison Reach (Missouri River mainstem between Garrison Dam and the City of Bismarck). 

FIGURE 5–3.—Thematic Map of the Sediments Delivered to the Missouri River 
78 

6.0 LINKAGE BETWEEN AGGRADATION AREAS AND SEDIMENT SOURCES 

The main stem of Missouri River located between the North Dakota—Montana 

state line and Lake Oahe was analyzed to determine whether the identified 

aggradation areas presented in Section 4 could be linked to sediment sources delivered from Montana and from 201 sub-watersheds in North Dakota presented in Section 5. Figure 6–1 shows the identified aggradation areas and delivered sediment 

to the main stem of the Missouri River from Montana and from each sub-watershed 

within the study area. The following conclusions can be drawn from this analysis. 

—The majority of the identified aggradation areas were located upstream of Lake 

Sakakawea in the close vicinity to the Montana/North Dakota border and in the 

vicinity of watersheds that showed large amounts of delivered land-based sediments. It appears that the aggradation areas were predominantly caused by the 

delivered sediment loads from the Yellowstone River and the Missouri River in 

Montana when the proportions of estimated delivered sediment load are compared to each other (Table 5–3). 

—The area between the city of Bismarck and Lake Oahe showed several 

aggradation areas with mostly low and moderate aggradation. Potential sources 

for sediment deposition were sediment erosion from instream erosion caused by 

hydropower at Garrison Dam and delivered land-based sediments from the 

Painted Woods Square Butts, Knife River, Heart River, and Cannonball River 

watersheds. The largest source of these aggradation areas are likely sediment 

deposits from eroded riverbed and riverbank sediments due to the impact of hydropower use at Garrison Dam. 

—Areas that showed little or no aggradation were generally located within the 

center of the lakes (Lake Sakakawea and Lake Oahe) and in the stream reach 

between Garrison Dam and the city of Bismarck in which instream erosion 

dominates (90 percent of the total sediment load originates from instream erosion). 

FIGURE 6–1.—Sediment Aggradation Areas and Amount of Delivered Sediment from 

each Sub-watershed 

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EXHIBIT A

Table A–1 through A–18: Land Use Distribution for the Yellowstone River Watershed and each HUC8 Watersheds within the Study Area. 

TABLE A–1.—LAND USE DISTRIBUTION OF THE YELLOWSTONE RIVER WATERSHED 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 68,614 0.84 

Developed, Open Space .................................................................................................................. 49,780 0.61 

Developed, Low Intensity ................................................................................................................ 18,155 0.22 

Developed, Medium Intensity .......................................................................................................... 2,958 0.04 

Developed, High Intensity ............................................................................................................... 433 0.01 

Barren Land (Rock/Sand/Clay) ....................................................................................................... 127,428 1.56 

Deciduous Forest ............................................................................................................................. 17,209 0.21 

Evergreen Forest ............................................................................................................................. 1,323,268 16.17 

Mixed Forest .................................................................................................................................... 4,332 0.05 

Shrub ............................................................................................................................................... 3,367,598 41.15 

Grassland/Herbaceous .................................................................................................................... 2,578,292 31.50 

Pasture/Hay ..................................................................................................................................... 211,442 2.58 

Cultivated Crops ............................................................................................................................. 264,217 3.23 

Woody Wetlands .............................................................................................................................. 84,425 1.03 

Emergent Herbaceous Wetlands ..................................................................................................... 57,212 0.70 

Perennial Ice/Snow .......................................................................................................................... 8,417 0.10 

Total ................................................................................................................................... 8,175,362 100.00 

TABLE A–2.—LAND USE DISTRIBUTION OF THE LAKE SAKAKAWEA WATERSHED (HUC 10110101) 

NLCD Land Use Type Hectare Percent 

Open Water .................................................................................................................................... 151,781 8 .90 

Developed, Open Space ................................................................................................................ 52,092 3 .06 

Developed, Low Intensity .............................................................................................................. 5,018 0 .29 

Developed, Medium Intensity ........................................................................................................ 591 0 .03 

Developed, High Intensity ............................................................................................................. 107 0 .010 

Barren Land (Rock/Sand/Clay) ..................................................................................................... 7,611 0 .45 

Deciduous Forest ........................................................................................................................... 37,138 2 .18 

Evergreen Forest ........................................................................................................................... 1,207 0 .07 

Mixed Forest .................................................................................................................................. 2,968 0 .17 
81 

TABLE A–2.—LAND USE DISTRIBUTION OF THE LAKE SAKAKAWEA WATERSHED (HUC 10110101)— 

Continued 

NLCD Land Use Type Hectare Percent 

Shrub ............................................................................................................................................. 23,126 1 .36 

Grassland/Herbaceous .................................................................................................................. 639,752 37 .52 

Pasture/Hay ................................................................................................................................... 24,466 1 .43 

Cultivated Crops ........................................................................................................................... 705,176 41 .36 

Woody Wetlands ............................................................................................................................ 11,687 0 .69 

Emergent Herbaceous Wetlands ................................................................................................... 42,270 2 .48 

Total ................................................................................................................................. 1,704,993 100 .00 

TABLE A–3.—LAND USE DISTRIBUTION OF THE LITTLE MUDDY RIVER WATERSHED (HUC 

10110102) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 3,452 1.46 

Developed, Open Space .................................................................................................................. 9,512 4.03 

Developed, Low Intensity ................................................................................................................ 377 0.16 

Developed, Medium Intensity .......................................................................................................... 29 0.01 

Developed, High Intensity ............................................................................................................... 3 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 46 0.02 

Deciduous Forest ............................................................................................................................. 232 0.10 

Evergreen Forest ............................................................................................................................. 16 0.01 

Mixed Forest .................................................................................................................................... 31 0.01 

Shrub ............................................................................................................................................... 3,303 1.40 

Grassland/Herbaceous .................................................................................................................... 51,703 21.89 

Pasture/Hay ..................................................................................................................................... 740 0.31 

Cultivated Crops ............................................................................................................................. 161,623 68.44 

Woody Wetlands .............................................................................................................................. 670 0.28 

Emergent Herbaceous Wetlands ..................................................................................................... 4,412 1.87 

Total ................................................................................................................................... 236,148 100.00 

TABLE A–4.—LAND USE DISTRIBUTION OF THE UPPER LITTLE MISSOURI RIVER WATERSHED (HUC 

10110201) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 566 0.06 

Developed, Open Space .................................................................................................................. 3,960 0.45 

Developed, Low Intensity ................................................................................................................ 483 0.05 

Developed, Medium Intensity .......................................................................................................... 14 ....................

Developed, High Intensity ............................................................................................................... 1 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 1,729 0.19 

Deciduous Forest ............................................................................................................................. 686 0.08 

Evergreen Forest ............................................................................................................................. 30,083 3.39 

Mixed Forest .................................................................................................................................... 1 ....................

Shrub ............................................................................................................................................... 284,486 32.02 

Grassland/Herbaceous .................................................................................................................... 514,185 57.88 

Pasture/Hay ..................................................................................................................................... 1,710 0.19 

Cultivated Crops ............................................................................................................................. 40,017 4.50 

Woody Wetlands .............................................................................................................................. 4,165 0.47 

Emergent Herbaceous Wetlands ..................................................................................................... 6,316 0.71 

Total ................................................................................................................................... 888,402 100.00 

TABLE A–5.—LAND USE DISTRIBUTION OF THE BOXELDER CREEK WATERSHED (HUC 10110202) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 219 0.07 
82 

TABLE A–5.—LAND USE DISTRIBUTION OF THE BOXELDER CREEK WATERSHED (HUC 

10110202)—Continued 

NLCD Land Use Type Hectare Percent 

Developed, Open Space .................................................................................................................. 563 0.18 

Developed, Low Intensity ................................................................................................................ 130 0.04 

Developed, Medium Intensity .......................................................................................................... .................... ....................

Developed, High Intensity ............................................................................................................... .................... ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 324 0.11 

Deciduous Forest ............................................................................................................................. 218 0.07 

Evergreen Forest ............................................................................................................................. 8,069 2.62 

Mixed Forest .................................................................................................................................... .................... ....................

Shrub ............................................................................................................................................... 82,732 26.84 

Grassland/Herbaceous .................................................................................................................... 197,962 64.21 

Pasture/Hay ..................................................................................................................................... 116 0.04 

Cultivated Crops ............................................................................................................................. 14,232 4.62 

Woody Wetlands .............................................................................................................................. 2,246 0.73 

Emergent Herbaceous Wetlands ..................................................................................................... 1,484 0.48 

Total ................................................................................................................................... 308,294 100.00 

TABLE A–6.—LAND USE DISTRIBUTION OF THE MIDDLE LITTLE MISSOURI RIVER WATERSHED (HUC 

10110203) 

NLCD Land Use Type Hectare Percent 

Open Water .................................................................................................................................... 3,410 0.61 

Developed, Open Space ................................................................................................................ 7,332 1.30 

Developed, Low Intensity .............................................................................................................. 777 0.14 

Developed, Medium Intensity ........................................................................................................ 15 ....................

Developed, High Intensity ............................................................................................................. 0 .4 ....................

Barren Land (Rock/Sand/Clay) ..................................................................................................... 7,542 1.34 

Deciduous Forest ........................................................................................................................... 16,637 2.95 

Evergreen Forest ........................................................................................................................... 8,621 1.53 

Mixed Forest .................................................................................................................................. 2,288 0.41 

Shrub ............................................................................................................................................. 61,781 10.96 

Grassland/Herbaceous .................................................................................................................. 354,883 62.98 

Pasture/Hay ................................................................................................................................... 13,986 2.48 

Cultivated Crops ........................................................................................................................... 81,856 14.53 

Woody Wetlands ............................................................................................................................ 3,475 0.62 

Emergent Herbaceous Wetlands ................................................................................................... 921 0.16 

Total ................................................................................................................................. 563,524 100.00 

TABLE A–7.—LAND USE DISTRIBUTION OF THE BEAVER CREEK WATERSHED (HUC 10110204) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 278 0.12 

Developed, Open Space .................................................................................................................. 5,040 2.23 

Developed, Low Intensity ................................................................................................................ 675 0.30 

Developed, Medium Intensity .......................................................................................................... 73 0.03 

Developed, High Intensity ............................................................................................................... 4 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 1,796 0.79 

Deciduous Forest ............................................................................................................................. 2,926 1.29 

Evergreen Forest ............................................................................................................................. 1,591 0.70 

Mixed Forest .................................................................................................................................... 418 0.18 

Shrub ............................................................................................................................................... 14,944 6.60 

Grassland/Herbaceous .................................................................................................................... 112,922 49.87 

Pasture/Hay ..................................................................................................................................... 11,595 5.12 

Cultivated Crops ............................................................................................................................. 71,494 31.58 

Woody Wetlands .............................................................................................................................. 2,155 0.95 

Emergent Herbaceous Wetlands ..................................................................................................... 508 0.22 

Total ................................................................................................................................... 226,420 100.00 
83 

TABLE A–8.—LAND USE DISTRIBUTION OF THE LOWER LITTLE MISSOURI RIVER WATERSHED (HUC 

10110205) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 7,970 1.70 

Developed, Open Space .................................................................................................................. 3,635 0.78 

Developed, Low Intensity ................................................................................................................ 710 0.15 

Developed, Medium Intensity .......................................................................................................... 38 0.01 

Developed, High Intensity ............................................................................................................... 4 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 15,876 3.39 

Deciduous Forest ............................................................................................................................. 58,399 12.48 

Evergreen Forest ............................................................................................................................. 9,763 2.09 

Mixed Forest .................................................................................................................................... 5,671 1.21 

Shrub ............................................................................................................................................... 38,440 8.21 

Grassland/Herbaceous .................................................................................................................... 260,691 55.71 

Pasture/Hay ..................................................................................................................................... 9,011 1.93 

Cultivated Crops ............................................................................................................................. 49,411 10.56 

Woody Wetlands .............................................................................................................................. 4,990 1.07 

Emergent Herbaceous Wetlands ..................................................................................................... 3,330 0.71 

Total ................................................................................................................................... 467,939 100.00 

TABLE A–9.—LAND USE DISTRIBUTION OF THE PAINTED WOODS-SQUARE BUTTE WATERSHED 

(HUC 10130101) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 29,657 4.62 

Developed, Open Space .................................................................................................................. 24,365 3.79 

Developed, Low Intensity ................................................................................................................ 1,899 0.30 

Developed, Medium Intensity .......................................................................................................... 307 0.05 

Developed, High Intensity ............................................................................................................... 21 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 813 0.13 

Deciduous Forest ............................................................................................................................. 8,259 1.29 

Evergreen Forest ............................................................................................................................. 52 0.01 

Mixed Forest .................................................................................................................................... 53 0.01 

Shrub ............................................................................................................................................... 324 0.05 

Grassland/Herbaceous .................................................................................................................... 267,816 41.71 

Pasture/Hay ..................................................................................................................................... 58,377 9.09 

Cultivated Crops ............................................................................................................................. 204,979 31.92 

Woody Wetlands .............................................................................................................................. 17,615 2.74 

Emergent Herbaceous Wetlands ..................................................................................................... 27,564 4.29 

Total ................................................................................................................................... 642,103 100.00 

TABLE A–10.—LAND USE DISTRIBUTION OF THE UPPER LAKE OAHE WATERSHED (HUC 10130102) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 59,833 6.55 

Developed, Open Space .................................................................................................................. 19,825 2.17 

Developed, Low Intensity ................................................................................................................ 3,306 0.36 

Developed, Medium Intensity .......................................................................................................... 740 0.08 

Developed, High Intensity ............................................................................................................... 262 0.03 

Barren Land (Rock/Sand/Clay) ....................................................................................................... 2,429 0.27 

Deciduous Forest ............................................................................................................................. 6,871 0.75 

Evergreen Forest ............................................................................................................................. 125 0.01 

Mixed Forest .................................................................................................................................... 82 0.01 

Shrub ............................................................................................................................................... 1,420 0.16 

Grassland/Herbaceous .................................................................................................................... 606,052 66.34 

Pasture/Hay ..................................................................................................................................... 38,323 4.19 

Cultivated Crops ............................................................................................................................. 152,196 16.66 

Woody Wetlands .............................................................................................................................. 9,059 0.99 

Emergent Herbaceous Wetlands ..................................................................................................... 13,036 1.43 
84 

TABLE A–10.—LAND USE DISTRIBUTION OF THE UPPER LAKE OAHE WATERSHED (HUC 

10130102)—Continued 

NLCD Land Use Type Hectare Percent 

Total ................................................................................................................................... 913,559 100.00 

TABLE A–11.—LAND USE DISTRIBUTION OF THE APPLE CREEK WATERSHED (HUC 10130103) 

NLCD Land Use Type Hectare Percent 

Open Water .................................................................................................................................... 71,174 7 .95 

Developed, Open Space ................................................................................................................ 28,751 3 .21 

Developed, Low Intensity .............................................................................................................. 2,643 0 .30 

Developed, Medium Intensity ........................................................................................................ 706 0 .08 

Developed, High Intensity ............................................................................................................. 189 0 .02 

Barren Land (Rock/Sand/Clay) ..................................................................................................... 323 0 .04 

Deciduous Forest ........................................................................................................................... 344 0 .04 

Evergreen Forest ........................................................................................................................... 18 ......................

Mixed Forest .................................................................................................................................. 23 ......................

Shrub ............................................................................................................................................. 523 0 .060 

Grassland/Herbaceous .................................................................................................................. 509,259 56 .87 

Pasture/Hay ................................................................................................................................... 71,997 8 .04 

Cultivated Crops ........................................................................................................................... 172,864 19 .30 

Woody Wetlands ............................................................................................................................ 527 0 .06 

Emergent Herbaceous Wetlands ................................................................................................... 36,198 4 .04 

Total ................................................................................................................................. 895,537 100 .00 

TABLE A–12.—LAND USE DISTRIBUTION OF THE BEAVER OAHE WATERSHED (HUC 10130104) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 7,883 2.98 

Developed, Open Space .................................................................................................................. 8,631 3.26 

Developed, Low Intensity ................................................................................................................ 1,049 0.40 

Developed, Medium Intensity .......................................................................................................... 159 0.06 

Developed, High Intensity ............................................................................................................... 40 0.02 

Barren Land (Rock/Sand/Clay) ....................................................................................................... 270 0.10 

Deciduous Forest ............................................................................................................................. 208 0.08 

Evergreen Forest ............................................................................................................................. 2 ....................

Mixed Forest .................................................................................................................................... .................... ....................

Shrub ............................................................................................................................................... 2,005 0.76 

Grassland/Herbaceous .................................................................................................................... 151,276 57.16 

Pasture/Hay ..................................................................................................................................... 27,906 10.54 

Cultivated Crops ............................................................................................................................. 64,086 24.21 

Woody Wetlands .............................................................................................................................. 225 0.08 

Emergent Herbaceous Wetlands ..................................................................................................... 933 0.35 

Total ................................................................................................................................... 264,671 100.00 

TABLE A–13.—LAND USE DISTRIBUTION OF THE KNIFE RIVER WATERSHED (HUC 10130201) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 1,827 0.28 

Developed, Open Space .................................................................................................................. 17,360 2.68 

Developed, Low Intensity ................................................................................................................ 1,578 0.24 

Developed, Medium Intensity .......................................................................................................... 199 0.03 

Developed, High Intensity ............................................................................................................... 44 0.01 

Barren Land (Rock/Sand/Clay) ....................................................................................................... 607 0.09 

Deciduous Forest ............................................................................................................................. 8,573 1.32 

Evergreen Forest ............................................................................................................................. 315 0.05 

Mixed Forest .................................................................................................................................... 176 0.03 

Shrub ............................................................................................................................................... 5,291 0.82 

Grassland/Herbaceous .................................................................................................................... 371,983 57.34 
85 

TABLE A–13.—LAND USE DISTRIBUTION OF THE KNIFE RIVER WATERSHED (HUC 10130201)— 

Continued 

NLCD Land Use Type Hectare Percent 

Pasture/Hay ..................................................................................................................................... 51,626 7.96 

Cultivated Crops ............................................................................................................................. 181,352 27.95 

Woody Wetlands .............................................................................................................................. 6,354 0.98 

Emergent Herbaceous Wetlands ..................................................................................................... 1,484 0.23 

Total ................................................................................................................................... 648,771 100.00 

TABLE A–14.—LAND USE DISTRIBUTION OF THE UPPER HEART WATERSHED (HUC 10130202) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 2,667 0.60 

Developed, Open Space .................................................................................................................. 16,584 3.73 

Developed, Low Intensity ................................................................................................................ 3,026 0.68 

Developed, Medium Intensity .......................................................................................................... 567 0.13 

Developed, High Intensity ............................................................................................................... 60 0.01 

Barren Land (Rock/Sand/Clay) ....................................................................................................... 1,095 0.25 

Deciduous Forest ............................................................................................................................. 1,200 0.27 

Evergreen Forest ............................................................................................................................. 56 0.01 

Mixed Forest .................................................................................................................................... 45 0.01 

Shrub ............................................................................................................................................... 2,354 0.53 

Grassland/Herbaceous .................................................................................................................... 178,175 40.08 

Pasture/Hay ..................................................................................................................................... 45,944 10.33 

Cultivated Crops ............................................................................................................................. 187,860 42.26 

Woody Wetlands .............................................................................................................................. 4,584 1.03 

Emergent Herbaceous Wetlands ..................................................................................................... 349 0.08 

Total ................................................................................................................................... 444,566 100.00 

TABLE A–15.—LAND USE DISTRIBUTION OF THE LOWER HEART RIVER WATERSHED (HUC 

10130203) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 2,296 0.54 

Developed, Open Space .................................................................................................................. 14,194 3.36 

Developed, Low Intensity ................................................................................................................ 1,538 0.36 

Developed, Medium Intensity .......................................................................................................... 271 0.06 

Developed, High Intensity ............................................................................................................... 31 0.01 

Barren Land (Rock/Sand/Clay) ....................................................................................................... 605 0.14 

Deciduous Forest ............................................................................................................................. 6,180 1.46 

Evergreen Forest ............................................................................................................................. 61 0.01 

Mixed Forest .................................................................................................................................... 56 0.01 

Shrub ............................................................................................................................................... 915 0.22 

Grassland/Herbaceous .................................................................................................................... 217,000 51.30 

Pasture/Hay ..................................................................................................................................... 29,785 7.04 

Cultivated Crops ............................................................................................................................. 141,800 33.52 

Woody Wetlands .............................................................................................................................. 7,183 1.70 

Emergent Herbaceous Wetlands ..................................................................................................... 1,113 0.26 

Total ................................................................................................................................... 423,027 100.00 

TABLE A–16.—LAND USE DISTRIBUTION OF THE UPPER CANNONBALL RIVER WATERSHED (HUC 

10130204) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 1,324 0.31 

Developed, Open Space .................................................................................................................. 14,097 3.33 

Developed, Low Intensity ................................................................................................................ 860 0.20 
86 

TABLE A–16.—LAND USE DISTRIBUTION OF THE UPPER CANNONBALL RIVER WATERSHED (HUC 

10130204)—Continued 

NLCD Land Use Type Hectare Percent 

Developed, Medium Intensity .......................................................................................................... 31 0.01 

Developed, High Intensity ............................................................................................................... 4 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 332 0.08 

Deciduous Forest ............................................................................................................................. 997 0.24 

Evergreen Forest ............................................................................................................................. 108 0.03 

Mixed Forest .................................................................................................................................... 17 ....................

Shrub ............................................................................................................................................... 1,037 0.24 

Grassland/Herbaceous .................................................................................................................... 139,550 32.93 

Pasture/Hay ..................................................................................................................................... 57,497 13.57 

Cultivated Crops ............................................................................................................................. 204,153 48.17 

Woody Wetlands .............................................................................................................................. 3,103 0.73 

Emergent Herbaceous Wetlands ..................................................................................................... 718 0.17 

Total ................................................................................................................................... 423,827 100.00 

TABLE A–17.—LAND USE DISTRIBUTION OF THE CEDAR CREEK WATERSHED (HUC 10130205) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 1,453 0.32 

Developed, Open Space .................................................................................................................. 12,952 2.82 

Developed, Low Intensity ................................................................................................................ 564 0.12 

Developed, Medium Intensity .......................................................................................................... 8 ....................

Developed, High Intensity ............................................................................................................... 2 ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 219 0.05 

Deciduous Forest ............................................................................................................................. 662 0.14 

Evergreen Forest ............................................................................................................................. 80 0.02 

Mixed Forest .................................................................................................................................... 24 0.01 

Shrub ............................................................................................................................................... 891 0.19 

Grassland/Herbaceous .................................................................................................................... 194,924 42.49 

Pasture/Hay ..................................................................................................................................... 68,676 14.97 

Cultivated Crops ............................................................................................................................. 174,620 38.07 

Woody Wetlands .............................................................................................................................. 3,304 0.72 

Emergent Herbaceous Wetlands ..................................................................................................... 361 0.08 

Total ................................................................................................................................... 458,741 100.00 

TABLE A–18.—LAND USE DISTRIBUTION OF THE LOWER CANNONBALL RIVER WATERSHED (HUC 

10130206) 

NLCD Land Use Type Hectare Percent 

Open Water ..................................................................................................................................... 1,125 0.49 

Developed, Open Space .................................................................................................................. 3,709 1.60 

Developed, Low Intensity ................................................................................................................ 90 0.04 

Developed, Medium Intensity .......................................................................................................... 8 ....................

Developed, High Intensity ............................................................................................................... .................... ....................

Barren Land (Rock/Sand/Clay) ....................................................................................................... 240 0.10 

Deciduous Forest ............................................................................................................................. 1,362 0.59 

Evergreen Forest ............................................................................................................................. 42 0.02 

Mixed Forest .................................................................................................................................... 23 0.01 

Shrub ............................................................................................................................................... 265 0.11 

Grassland/Herbaceous .................................................................................................................... 178,363 77.01 

Pasture/Hay ..................................................................................................................................... 8,062 3.48 

Cultivated Crops ............................................................................................................................. 35,417 15.29 

Woody Wetlands .............................................................................................................................. 2,186 0.94 

Emergent Herbaceous Wetlands ..................................................................................................... 707 0.31 

Total ................................................................................................................................... 231,600 100.00 
87 

EXHIBIT B

Figure B–1 through B–7: Time Series of TSS and Flow at USGS Monitoring Stations at Boundary Stations and within the Missouri River in North Dakota. 

FIGURE B–1.—TSS and Flow Measurements at USGS 06185500, Missouri River 

(Culbertson, MT) 

FIGURE B–2.—TSS and Flow Measurements at USGS 06342500, Missouri River 

(Bismarck, ND) 
88 

FIGURE B–3.—TSS and Flow Meas. at USGS 06329500, Yellowstone River (Sidney, 

MT), 1965–1980 

FIGURE B–4.—TSS and Flow Meas. at USGS 06329500, Yellowstone River (Sidney, 

MT), 1980–1995 
89 

FIGURE B–5.—TSS and Flow Measurements at USGS 06329500, Yellowstone River 

(Sidney, MT),1995–2008 

FIGURE B–6.—TSS and Flow Measurements at USGS 06340500, Knife River (at 

Hazen, ND) 
90 

FIGURE B–7.—TSS and Flow Measurements at USGS 0634900, Heart River (near 

Mandan, ND) 

APPENDIX B—ECONOMIC IMPACT OF SEDIMENTATION AND EROSION ALONG THE

MISSOURI RIVER, NORTH DAKOTA

1.0 INTRODUCTION 

The Louis Berger Group Inc. (Berger) was tasked by the U.S. Army Corps of Engineers (USACE) to assess impacts of sedimentation in the Missouri River Basin within the State of North Dakota. This assessment is intended to meet the level of effort 

defined in the Missouri River Protection and Improvement Act. The assessment has 

two objectives. First, Berger identified sources and deposit locations of sediment 

within the Missouri River Basin in the State of North Dakota, utilizing existing 

data and information. This task was completed in August (2008). Next, the team 

analyzed the potential impacts of sedimentation, using the results of Task 5A on 

important issues and resources including: 

—Federal, tribal, State and Regional Economies; 

—Recreation; 

—Hydropower Generation; 

—Fish and Wildlife; 

—Flood Control; and 

—Indian and Non-Indian Historical and Cultural sites. 

Under this subtask the direct economic impacts associated with increased sedimentation and erosion along the Missouri River in the State of North Dakota were 

evaluated. The evaluation includes a qualitative discussion on whether or not the 

direct economic impacts are relevant in scale and location to Federal, tribal, State, 

and Regional economies. For instance, certain impacts may be very relevant to tribal or regional economies due to the location of impacts but may not be relevant at 

the State or national levels due to the size of the impact. Where possible, these distinctions will be made with direct economic impacts identified in this report. 

Berger utilized an integrated approach to evaluate the economic impacts using the 

results of other tasks that evaluated the resources listed above. As such, results of 

other subtasks were important to the economic evaluation such as flood control, 

recreation, and hydroelectric generation. Thus the task leads worked closely together to properly identify and quantify, where possible, the potential impacts in a 

way that can be used to evaluate economic implications. 

Louis Berger has identified potential impacts from erosion and sedimentation that 

may have economic impacts to Federal, tribal, State and Regional economies. These 

potential impacts were identified in the results of other subtasks as well as additional literature searches and interviews with subject matter experts. The potential 

impacts would be associated with the following resources or activities including: 
91 

1 USDA National Agricultural Statistics Service (NASS) Cropland Data Layer for Midwestern/ 

Prairie States, 2007. 

—Land Use 

—Coal-Fired Power Production 

—Hydropower Production 

—Recreation 

—Water Supply Intakes 

Each of these potential impacts is discussed below. 

2.0 LAND USE 

The initial assumption used for this analysis is that local land use near or adjacent to the Missouri River can be impacted by fluvial geomorphic changes, including 

rapid aggregation and erosion of riparian lands, and that these changes would lead 

to complications for landowners. The evaluations to date show that land uses most 

likely to be impacted by erosion and sedimentation include agricultural uses (grasslands and pasture, cultivated crops) and small areas of development. The developed 

areas are near the cities of Williston and Bismarck. 

2.1 Agriculture 

To evaluate sedimentation impacts to agricultural lands, Berger first evaluated 

the land uses within the aggradation areas identified in Task 5A. The GIS layers 

for the aggradation areas were over laid on agricultural acreage published by the 

U.S. Department of Agriculture.1 The land use categories were sorted to include 

only those uses that were thought to be in agriculture production. Thus, areas identified as ‘‘wetlands’’ were removed from the analysis. The results provided a summary of potential agricultural land uses that may be impacted by sedimentation 

along the Missouri River. Table 2–1 summarizes the acreage by county and level 

of impact and shows that in total approximated 43,000 agricultural acres fall within 

the aggradations areas. This total distribution of acreage includes 37 percent in low 

impact areas (16,000), 59 percent in medium impact areas (25,600) and 4 percent 

(1,600) in high impact areas. 

TABLE 2–1.—ESTIMATED AGRICULTURAL ACREAGE WITHIN THE AGGRADATION AREAS ALONG THE 

MISSOURI RIVER IN NORTH DAKOTA 

County 

Level of Impact 

Total 

Low Medium High 

Williams ........................................................................................ 3,560 11,947 211 15,717 

McKenzie ....................................................................................... 3,162 1,066 182 4,411 

Mountrail ....................................................................................... 902 294 .................... 1,196 

Dunn ............................................................................................. 6 .................... .................... 6 

Oliver ............................................................................................. .................... 7,172 .................... 7,172 

Morton ........................................................................................... 376 663 508 1,547 

Sioux ............................................................................................. 5,539 1,020 .................... 6,558 

McLean .......................................................................................... 73 264 .................... 337 

Burleigh ........................................................................................ 373 751 717 1,841 

Emmons ........................................................................................ 2,135 2,420 .................... 4,555 

Total ................................................................................ 16,126 25,596 1,618 43,339 

Table 2–2 through Table 2–11 shows a further breakdown of agricultural land use 

types impacted within each county. 

TABLE 2–2.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—WILLIAMS COUNTY 

Crop Type 

Level of Impact Area 

Total 

Low Medium High 

Alfalfa ........................................................................................... 680 331 5 1,016 

Barley ............................................................................................ 128 976 .................... 1,104 

Canola ........................................................................................... 4 58 1 62 

Corn .............................................................................................. 8 757 .................... 764

Clover/Wildflowers ......................................................................... 1 2 .................... 3 

Durum Wheat ................................................................................ 74 1,609 5 1,688 

Fallow/Idle Cropland ..................................................................... 32 255 1 288 
92 

TABLE 2–2.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—WILLIAMS 

COUNTY—Continued 

Crop Type 

Level of Impact Area 

Total 

Low Medium High 

Flaxseed ........................................................................................ .................... 30 .................... 30 

Herbaceous Grassland .................................................................. 2,301 4,831 190 7,322 

Lentils ........................................................................................... 1 561 4 566 

Misc. Vegs. And Fruits ................................................................. .................... 7 .................... 7 

Oats .............................................................................................. 4 13 1 18 

Peas .............................................................................................. 8 475 4 486 

Potatoes ........................................................................................ .................... 215 .................... 215 

Safflower ....................................................................................... 3 3 1 7 

Soybeans ....................................................................................... .................... 6 .................... 6 

Spring Wheat ................................................................................ 124 1,187 1 1,311 

Sugar beets .................................................................................. 164 406 .................... 570 

Sunflowers .................................................................................... 2 152 .................... 153 

Winter Wheat ................................................................................ 26 73 .................... 100 

Total ................................................................................ 3,560 11,947 211 15,717 

TABLE 2–3.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—MCKENZIE COUNTY 

Crop Type 

Level of Impact Total Low Medium High 

Alfalfa ........................................................................................... 335 2 .................... 337

Barley ............................................................................................ 25 4 1 29 

Canola ........................................................................................... 7 2 .................... 9 

Corn .............................................................................................. 11 17 4 32 

Clover/Wildflowers ......................................................................... 2 .................... .................... 2 

Dry Beans ..................................................................................... .................... 1 .................... 1 

Durum Wheat ................................................................................ 84 17 .................... 101 

Fallow/Idle Cropland ..................................................................... 102 3 .................... 105 

Flaxseed ........................................................................................ 2 1 .................... 2 

Herbaceous Grassland .................................................................. 2,428 993 174 3,595 

Lentils ........................................................................................... 2 .................... .................... 2 

Millet ............................................................................................. 1 1 .................... 2 

Misc. Vegs. And Fruits ................................................................. 1 .................... .................... 1 

Oats .............................................................................................. 6 .................... .................... 6 

Peas .............................................................................................. 26 .................... .................... 26 

Safflower ....................................................................................... 5 1 .................... 6 

Sunflowers .................................................................................... 4 .................... .................... 4 

Spring Wheat ................................................................................ 118 20 3 141 

Sugar beets .................................................................................. 2 3 .................... 4 

Winter Wheat ................................................................................ 2 2 1 5 

Total ................................................................................ 3,162 1,066 182 4,411 

TABLE 2–4.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—MOUNTRAIL COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Barley ............................................................................................ 17 .................... .................... 17 

Canola ........................................................................................... 1 1 .................... 3 

Durum Wheat ................................................................................ 10 .................... .................... 10 

Fallow/Idle Cropland ..................................................................... 1 .................... .................... 1 

Herbaceous Grassland .................................................................. 772 290 .................... 1,062 

Flaxseed ........................................................................................ 1 .................... .................... 1 

Oats .............................................................................................. 1 .................... .................... 1 

Peas .............................................................................................. 5 1 .................... 6 

Spring Wheat ................................................................................ 14 1 .................... 15 

Sunflowers .................................................................................... 1 .................... .................... 1 
93 

TABLE 2–4.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—MOUNTRAIL 

COUNTY—Continued 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Winter Wheat ................................................................................ 81 .................... .................... 81 

Total ................................................................................ 902 294 .................... 1,196 

TABLE 2–5.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—DUNN COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Herbaceous Grassland .................................................................. 6 .................... .................... 6

Total ................................................................................ 6 .................... .................... 6 

TABLE 2–6.—AGRICULTURAL LAND WITHIN THE AGGRADATION AREAS—MCLEAN COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Alfalfa ........................................................................................... .................... 9 .................... 9 

Barley ............................................................................................ 1 1 .................... 2 

Canola ........................................................................................... .................... 1 .................... 1 

Corn .............................................................................................. .................... 7 .................... 7 

Dry Beans ..................................................................................... .................... 21 .................... 21 

Durum Wheat ................................................................................ .................... 1 .................... 1 

Herbaceous Grassland .................................................................. 71 220 .................... 291 

Other Small Grains ....................................................................... .................... 2 .................... 2 

Safflower ....................................................................................... .................... 1 .................... 1 

Spring Wheat ................................................................................ 1 2 .................... 4 

Total ................................................................................ 73 264 .................... 337 

TABLE 2–7.—AGRICULTURAL LAND WITHIN THE AGGRADATION AREAS—OLIVER COUNTY 

Crop Type 

Level of Impact Total Low Medium High 

Alfalfa ........................................................................................... .................... 444 .................... 444 

Barley ............................................................................................ .................... 73 .................... 73 

Canola ........................................................................................... .................... 23 .................... 23 

Corn .............................................................................................. .................... 2,141 .................... 2,141 

Dry Beans ..................................................................................... .................... 61 .................... 61 

Durum Wheat ................................................................................ .................... 16 .................... 16 

Fallow/Idle Cropland ..................................................................... .................... 11 .................... 11 

Flaxseed ........................................................................................ .................... 32 .................... 32 

Herbaceous Grassland .................................................................. .................... 2,450 .................... 2,450 

Millet ............................................................................................. .................... 1 .................... 1 

Oats .............................................................................................. .................... 19 .................... 19 

Peas .............................................................................................. .................... 33 .................... 33 

Safflower ....................................................................................... .................... 1 .................... 1 

Sorghum ........................................................................................ .................... 4 .................... 4 

Soybeans ....................................................................................... .................... 19 .................... 19 

Spring Wheat ................................................................................ .................... 1,644 .................... 1,644 

Sugar beets .................................................................................. .................... 1 .................... 1 

Sunflowers .................................................................................... .................... 196 .................... 196 

Winter Wheat ................................................................................ .................... 3 .................... 3 

Total ................................................................................ .................... 7,172 .................... 7,172 
94 

TABLE 2–8.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—MORTON COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Alfalfa ........................................................................................... 15 26 31 73 

Barley ............................................................................................ 1 2 27 31 

Corn .............................................................................................. 26 8 45 80 

Fallow/Idle Cropland ..................................................................... 6 .................... 1 7 

Herbaceous Grassland .................................................................. 312 617 355 1,284 

Oats .............................................................................................. .................... .................... 1 1 

Spring Wheat ................................................................................ 12 8 12 32 

Sunflowers .................................................................................... 4 .................... 2 5 

Winter Wheat ................................................................................ .................... .................... 34 34 

Total ................................................................................ 376 663 508 1,547 

TABLE 2–9.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—BURLEIGH COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Alfalfa ........................................................................................... 2 2 2 6 

Barley ............................................................................................ 2 3 1 5 

Canola ........................................................................................... .................... .................... 1 1 

Corn .............................................................................................. .................... 4 4 8 

Dry Beans ..................................................................................... .................... .................... .................... ....................

Fallow/Idle Cropland ..................................................................... .................... .................... 3 3 

Herbaceous Grassland .................................................................. 369 671 694 1,735 

Oats .............................................................................................. .................... 5 .................... 5 

Peas .............................................................................................. .................... 1 2 2 

Soybeans ....................................................................................... .................... .................... .................... ....................

Spring Wheat ................................................................................ .................... 64 11 75 

Winter Wheat ................................................................................ .................... 1 .................... 1 

Total ................................................................................ 373 751 717 1,841 

TABLE 2–10.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—EMMONS COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Alfalfa ........................................................................................... 7 1 .................... 8 

Barley ............................................................................................ 7 3 .................... 10 

Canola ........................................................................................... 1 1 .................... 2 

Corn .............................................................................................. 8 .................... .................... 8 

Dry Beans ..................................................................................... 5 .................... .................... 5 

Fallow/Idle Cropland ..................................................................... 5 5 .................... 10 

Herbaceous Grassland .................................................................. 2,013 2,377 .................... 4,390 

Oats .............................................................................................. 1 2 .................... 2 

Potatoes ........................................................................................ 27 .................... .................... 27 

Soybeans ....................................................................................... 1 .................... .................... 1 

Spring Wheat ................................................................................ 48 23 .................... 71 

Sunflowers .................................................................................... 12 .................... .................... 12 

Winter Wheat ................................................................................ 1 8 .................... 9 

Total ................................................................................ 2,135 2,420 .................... 4,555 

TABLE 2–11.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—SIOUX COUNTY 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Alfalfa ........................................................................................... 177 87 .................... 264 
95 

2Where possible, 2009 Projected Crop Budgets published by the North Dakota Extension 

Agency were used to estimate average revenue per acre and returns per acre. For crops that 

did not have a projected budget (e.g. sugar beets, potatoes) data on average productivity and 

prices were obtained for the National Agricultural Statistical Service for North Dakota. 

TABLE 2–11.—AGRICULTURAL LAND USES WITHIN THE AGGRADATION AREAS—SIOUX COUNTY— 

Continued 

Crop Type 

Level of Impact 

Total 

Low Medium High 

Barley ............................................................................................ 57 26 .................... 83 

Canola ........................................................................................... 2 4 .................... 6 

Corn .............................................................................................. 721 6 .................... 727

Durum Wheat ................................................................................ .................... .................... .................... ....................

Fallow/Idle Cropland ..................................................................... 7 .................... .................... 7 

Flaxseed ........................................................................................ 1 .................... .................... 1 

Herbaceous Grassland .................................................................. 4,234 853 .................... 5,087 

Millet ............................................................................................. .................... 1 .................... 1 

Oats .............................................................................................. 49 .................... .................... 49 

Peas .............................................................................................. .................... 1 .................... 1 

Soybeans ....................................................................................... 4 3 .................... 7 

Spring Wheat ................................................................................ 223 29 .................... 252 

Sunflowers .................................................................................... 43 10 .................... 54 

Winter Wheat ................................................................................ 20 .................... .................... 20 

Total ................................................................................ 5,539 1,020 .................... 6,558 

While the total acreage within each impact magnitude category and land use was 

identified, it is uncertain how these different areas would be impacted by sedimentation on an annual basis. For instance, it is possible that acreage within a low 

impact area would only be impacted during an extreme flood event. It is likely that 

acreage within medium and high impact areas would be impacted more often than 

acreage in low impact areas. Because of this uncertainty, it is impossible to estimate 

the economic impact on agricultural production from sedimentation. However, data 

was collected on the productivity, prices and returns by land use to gain an understanding of the importance of these areas to Federal, tribal, State and regional agricultural industries and economies. 

To estimate average economic returns from acreage within sedimentation impact 

areas, certain assumptions were needed regarding agricultural operations. For instance, herbaceous grasslands were assumed to be used for cattle operations (e.g. 

cow/calf). Cultivated crop production was assumed to follow the lands uses identified 

in the GIS layer. Berger then collected average productivity, crop and livestock 

prices, and average returns on labor and management from the National Agricultural Statistical Agency and the North Dakota Agricultural Extension Agency.2

These values were used in combination with acreage estimates to estimate annual 

revenues and returns. 

Table 2–12 shows the estimates of average total annual revenue and returns for 

acreage within each county that may be impacted by sedimentation. For all 43,300 

acres, average annual revenue was estimated to be $13.5 million and annual returns were estimated to $970,000. 

TABLE 2–12.—ESTIMATED ANNUAL REVENUES AND RETURNS TO AREAS POTENTIALLY IMPACTED 

BY SEDIMENTATION 

County Total Impacted 

Acreage Total Revenue Total Returns 

Williams ..................................................................................................... 15,717 $5,071,164 $501,793 

McKenzie .................................................................................................... 4,411 1,358,325 132,906 

Mountrail .................................................................................................... 1,196 395,671 25,236 

Dunn ........................................................................................................... 6 2,018 ( 1 ) 

Oliver .......................................................................................................... 7,172 1,724,668 112,531 

Morton ........................................................................................................ 1,547 493,904 3,546 

Sioux ........................................................................................................... 6,558 2,080,086 98,887 

McLean ....................................................................................................... 337 113,187 1,736 

Burleigh ...................................................................................................... 1,841 626,123 ¥77 
96 

3 USACE, Omaha District, Garrison Dam/Lake Sakakawea Master Plan with Integrated Programmatic Environmental Assessment, Missouri River, North Dakota, Update of Design Memorandum MGR–107D, December 14, 2007. 

TABLE 2–12.—ESTIMATED ANNUAL REVENUES AND RETURNS TO AREAS POTENTIALLY IMPACTED 

BY SEDIMENTATION—Continued 

County Total Impacted 

Acreage Total Revenue Total Returns 

Emmons ..................................................................................................... 4,555 1,609,779 102,561 

Total .............................................................................................. 43,339 13,474,924 979,119 

1 NA. 

According to the U.S. Bureau of Economic Analysis, value added produced by Agriculture, Forestry, Fishing and Hunting in 2007 was $2.1 billion for North Dakota. 

Comparing the estimated revenue from the potential impacted areas with the value 

added for the entire State from these industries, indicates the areas are a relatively 

small contributor to the industry and the State economy (less than 1 percent) as 

a whole. However, if increased sedimentation were to cause these areas to be removed from production, it would likely have a measurable impact on local communities, tribes and counties. This is especially true for counties with the large percentage of potentially impacted acreage (Williams, Sioux, Oliver and Emmons). 

It is noted here that the impacts discussed above are not related to lands already 

part of the flowage easements that have been purchased by the USACE. In 1996, 

Congress passed Public Law 104–303, which required the Federal Government to 

purchase flowage and saturation easements from willing sellers within the BufordTrenton Irrigation District located on the headwaters of the Garrison Dam/Lake 

Sakakawea project and southwest of Williston, North Dakota. According to the Garrison Dam/Lake Sakakawea Master Plan, published in December 2007, acquisition 

of flowage easements in the Buford-Trenton Irrigation District is nearly complete. 

The total flowage easement acreage was approximately 11,750.3 While individual 

owners were compensated for these easements, the State of North Dakota, county 

and local governments will continue to be impacted by the loss in tax base into the 

future due to the Federal acquisition of these easements. 

The analysis discussed above was only able to examine areas that may be impacted by increased sedimentation. There are other agricultural areas along the 

river that will also be affected by erosion. Stream bank erosion results in the permanent loss of flood plain land, leading to a loss of production for individual land owners. Louis Berger was unable to quantify the magnitude of this impact at this time 

given the availability of information and data. 

2.1.1. High Water Tables 

Berger has discovered that sedimentation may be impacting agricultural lands 

near Williston due higher water tables. These impacts may be causing additional 

acreage to go out of production. While there is antidotal evidence of this impact, no 

studies were located which evaluate the issue in detail. 

2.1.2. Potential Increased Flooding in Developed Areas 

Berger completed an evaluation of the potential impacts of sedimentation on flood 

control associated with the Missouri River in North Dakota. The analysis only included a review of Flood Insurance Studies (FIS) prepared by the Federal Emergency Management Agency (FEMA) for the Bismarck, North Dakota area to analyze 

changes in water surface elevation and its affects on flooding. At this time, new 

flood data has not been generated for significant portion of the Missouri River. The 

exception is Williams County near the city of Williston which is now being developed. Due to the lack of new flood data all along the Missouri River, the analysis 

was limited to the areas where historic and current flood data were available, particularly the areas surrounding the city of Bismarck. 

Sedimentation in the reach between the Garrison Dam and Lake Oahe has resulted in increased risk of flooding in the downstream reach between the dam and 

the headwater of Lake Oahe. Because of this sediment aggradation, the impact of 

ice dams on seasonal flooding is increasing. As a means to counter this impact, careful sequenced water releases during the winter months are made to decrease the 

potential for flooding caused by ice effects. Water releases from the Garrison Dam 

are also used to provide flood control during other seasons as well. 
97 

4 Remus, John, Personal Communication, November, 2008. 

5FEMA. Flood Insurance Study—Burleigh County, North Dakota and Incorporated Areas. FIS 

Number 3801 5CV000A. Federal Emergency Management Agency, July 2005. 6FEMA. National Flood Insurance Program, Flood Insurance Manual, May 2008, Revised October 2008. Accessed at http://www.fema.gov/pdf/nfip/manual200810/coverl102008.pdf. 7The city of Bismarck provided GIS layers showing building foot prints, the 1985 flood plain 

and the 2005 flood plain that was used for this analysis. 

Analysis of floodplain maps for the 1985 and 2005 Flood Insurance Study (FIS) 

for the city of Bismarck and parts of Burleigh County indicated that the area of the 

100-year floodplain has increased by nearly 28.6 percent within Burleigh County 

(Table 2–13). This may be attributed to areas with high aggradation and/or the natural morphology of the river changing and/or restricting the channel’s ability to convey the flow associated with a particular storm event. 

TABLE 2–13.—FLOODPLAIN AREA COMPARISON 

Burleigh County Bismarck City Limits 

1985 100-year Floodplain—28 mi2 ......................................... 1985 100-year Floodplain—2.7 mi2

2005 100-year Floodplain—36 mi2 ......................................... 2005 100-year Floodplain—3.6 mi2

mi2= square miles 

In urban areas such as Bismarck and Mandan, flood plain development restricts 

the Missouri River’s ability to accommodate increases flows during certain storm 

events (e.g. river channel has no room to widen without affecting properties). 

Aggradation in this area of the river compounds the problem resulting in an increase risk of flooding and the loss of property. Potential buyouts due to flooding 

concerns in the Bismarck-Mandan area are estimated at over $100 million.4 The impact of flooding is estimated to be greatest between RM 1300 and 1316, i.e., in 

downtown Bismarck and Mandan.5 Flooding also occurs outside of urbanized areas, 

affecting cropland and causing soil erosion. 

Property owners whose property now lies within the expanded flood plain may 

also be impacted by a decline property values and increased insurance cost. Homes, 

businesses, and agricultural land are among the types of properties most heavily affected by an increase in the 100-year flood plain. 

FEMA manages the National Flood Insurance Program (NFIP) which insures 

buildings and structures against flood damage. As a result of changes in the Flood 

Insurance Rate Map, all entities requiring a mortgage for structures on property 

within the 100-year floodplain will be required to purchase insurance under the 

NFIP. Owners of buildings must purchase insurance against damages to the structure of the building itself and also against damages to the contents of any floors 

below flood level that would be inundated in the event of a 100-year flood. Owners 

may purchase a basic level of coverage or increase coverage for an additional cost. 

The cost of the insurance is based on the area of the building (square feet). The insurance rate per square foot is dependent on the building’s characteristics, on the 

date of construction of the building, and on the ‘‘flood zone’’ that the building is located in. 

There are four different types of buildings covered under NFIP: 

—Non-residential 

—Single-family dwellings 

—Condominiums 

—2–4 family dwellings 

Each building type has a different flood insurance rate depending on the zone 

where it is located as delineated in FEMA’s Flood Insurance Rate Map (FIRM). It 

appears that areas impacted by the new delineation will be designated as either in 

FEMA’s Zone B or Zone C. 

Table 2–15 summarizes the insurance costs per square foot for buildings of various types located within FEMA’s Zone C. This table is based on the FEMA’s Flood 

Insurance Manual.6 At this time, it is unknown the exact number, type or square 

footage of structures that may be required to purchase flood insurance. However, 

an evaluation of GIS data 7 provided by the city of Bismarck associated with the 

1985 and 2005 Flood Insurance Study indicates that the number of structures within the floodplain has declined (Table 2–14). This indicates that the number of individuals or entities that would be subject to flood insurance may have actually declined in this area even with an increase in the size of the 100-year floodplain. 
98 

TABLE 2–14.—BUILDINGS WITHIN FLOOD PLAIN AREAS IN 1985 AND 2005 IN BISMARCK 

1985 Flood Plain 2005 Flood Plain 

1341 buildings (86 acres) ........................................................ 1332 buildings (78 acres) 

To gain an understanding of how individual property owners may be impacted by 

flood insurance, a simple example was developed to demonstrate the magnitude of 

flood insurance costs. Assume a single family unit of 1,500 square feet in size without a basement is located within the floodplain. Basic coverage would cost $1,170 

for building coverage and $1,800 for contents on an annual basis. 

As mentioned earlier, properties within the expanded flood plain are also likely 

to realize a decline in property value. At this time, it is not possible to quantify the 

potential decline in property values that may occur under this scenario. 
99 

TABLE 2–15.—ANNUAL INSURANCE RATES PER SQUARE FOOT FOR $100 IN COVERAGE FOR BUILDINGS IN ZONE C (BASIC/ADDITIONAL) 

Occupancy 

Single Family 2–4 Family Other Residential Non-Residential 

Building Contents Building Contents Building Contents Building Contents 

Building Type: 

No Basement/Enclosure ................................................................................................. .78/.21 1.20/.37 0.78/0.21 .................... 0.74/0.21 .................... 0.74/0.21 ....................With Basement ............................................................................................................... .89/.30 1.36/.43 0.89/0.30 .................... 0.95/0.30 .................... 0.95/0.30 ....................With Enclosure ............................................................................................................... .89/.34 1.36/.49 0.89/0.34 .................... 0.95/0.34 .................... 0.95/0.34 ....................Manufactured (Mobile) Home ........................................................................................ .78/.38 1.20/.37 .................... .................... .................... .................... 0.95/0.39 ....................

Contents Location: 

Basement & Above ........................................................................................................ .................... .................... .................... 1.53/0.56 .................... 1.53/0.56 .................... 1.58/0.61 Enclosure & Above ......................................................................................................... .................... .................... .................... 1.53/0.65 .................... 1.53/0.65 .................... 1.58/0.73 Lowest Floor Only—Above Ground Level ....................................................................... .................... .................... .................... 1.20/0.59 .................... 1.20/0.59 .................... 0.97/0.43 Lowest Floor Above Ground Level and Higher Floors .................................................... .................... .................... .................... 1.20/0.37 .................... 1.20/0.37 .................... 0.97/0.31 Above Ground Level—More than One Full Floor ........................................................... .................... .................... .................... 0.35/0.12 .................... 0.35/0.12 .................... 0.22/0.12 Manufactured (Mobile) Home ........................................................................................ .................... .................... .................... .................... .................... .................... .................... 0.85/0.53 

Source: FEMA, 2008. 
100 

8Thermal electric plants may either have a once through or closed loop cooling system. Once 

through systems can realize a reduction in thermal efficiencies from sedimentation. Closed cooling processes have potential withdrawal impacts as well as higher costs associated with water 

treatment. 

3.0 COAL-FIRED POWER GENERATION FACILITIES 

Berger has identified seven coal-fired power generation facilities in North Dakota 

that may be impacted by sedimentation or erosion along the Missouri River. Figure 

3–1 shows the location of these facilities relative to the sediment load map produced 

in the Sedimentation Report. Berger completed a series of interviews with managers 

at some of the facilities to gain knowledge on the potential impacts to their operations from sedimentation or erosion. Table 3–1 provides a summary of the plants, 

location, generation capacity, operator and a summary of impacts identified in the 

interviews. 

From these interviews, Berger learned the following regarding potential impacts. 

Thermoelectric power plants have two dominate uses for water to conduct basic operations: steam creation for driving turbines and water for condensing steam back 

to water, with the latter constituting the highest volume of water use. Problems incurred at facilities with once through cooling 8 from high sedimentation levels include degradation and plugging of the tubes and tube sheets in condensers, degradation of mechanical pumps and decreasing thermal efficiency. Associated impacts include having to reduce power production and more frequent maintenance. This can 

reduce the life span of mechanical pumps from 10 years to 7 years due to sedimentation requiring plants to obtain new, more expensive equipment increasing 

their costs. Many of those interviewed believe that larger costs are associated with 

the loss in capacity to generate electricity. This can lead to a reduction in revenue 

in the millions over the lifetime of the facility. In addition, sediment issues can necessitate additional maintenance over the life of the plant. 

To gain an understanding of the cost of lost energy production from thermal electric plants due to sedimentation issues, Berger was able to obtain some actual data 

from one of the facilities over the course of 8 months. The operator provided data 

on the reductions in capacity due to issues related to condensers. Reductions in capacity were due to the following: 

—Debris in the condenser causing a decline in efficiency; 

—Large ice dams during the winter months at the intake reducing inlet flows to 

the pumps; 

—Low river levels; and 

—River temperatures (Upper Thermal Discharge limitations). 
101 

FIGURE 3–1.—Location of Coal Fired Power Plants in North Dakota 
102 

TABLE 3–1.—IMPACTS OF SEDIMENTATION AND EROSION TO COAL-FIRED POWER PLANTS NEAR THE MISSOURI RIVER IN NORTH DAKOTA 

Power Plant Location Electric Generation Capacity Operator Issues Related to Sedimentation 

Antelope Valley ....... Beulah ............. Unit 1: 43 8mw; Unit 2: 438mw .... Basin Electric Power Co-op ............ Water withdrawals come from Sakakawea Reservoir (150 feet deep). No direct sedimentation 

impacts. Higher turbidity in the reservoir lead to higher water treatment costs because of a closed cooling process is employed. Potential sedimentation impacts to water withdrawals but no impact to plant efficiencies. 

Coal Creek .............. Underwood ....... Unit 1: 550mw; Unit 2: 550mw ...... Great River Energy Co-op ............... Higher turbidity in water source will cause an increase in water treatment costs because of 

a closed cooling process is employed. Potential sedimentation impacts to water withdrawals but no impact to plant efficiencies. 

Leland Olds ............ Stanton ............ Unit 1: 216mw; Unit 2: 440mw ...... Basin Electric Power Co-op ............ Missouri River provides once through cooling. The performance of the condensers can be adversely affected by the build-up of sediment, scale, corrosion or biological growth inside 

the tubes. Erosion can affect mechanical pumps. etc. Impacts can lead to a decrease in thermal efficiency and requires a reduction in electrical generation. 

Coyote ..................... Beulah ............. Unit 1: 4 14mw ............................... Otter Tail Corp ................................ Coyote is not a once through system; pump to secondary pond then from pond to plant. Siltation affects condensers, pumps and pipelines that bring water to the plant. Sedimentation impacts on condensers can cause millions of dollars in maintenance and replacement costs. For a 50 year plant, sediment issues can necessitate maintenance to occur 

once or twice over the 50 year lifetime. Sediment can also plug the river intake itself, which is an issue at this plant from time to time. If output from dam falls below 11,000 cfs, intakes will silt in. 

Milton R. Young ..... Center .............. Unit 1: 257mw; Unit 2: 454mw ...... Minnkota Power Co-op .................... Missouri River is the main source of surface water. Water removed from river is diverted to 

stand-alone man-made lake for once through cooling. 

Stanton ................... Stanton ............ Unit 1: 170mw ................................ Great River Energy Co-op ............... Missouri River provides once through cooling. Heskett Station ....... Mandan ........... Unit 1: 25mw; Unit 2: 75mw .......... Montana Dakota Utilities Co ........... Missouri River provides once through cooling. 
103 

Berger evaluated the data and selected occurrences that were most likely tied to 

increases in sedimentation. The results are summarized in Figure 3–2. Over the 8 

month period, this facility lost over 13,000 MWh in electricity generation due to 

sedimentation issues. To evaluate the value of this reduction in capacity, Berger utilized wholesale electricity rates published by the Energy Information Agency for the 

Cinergy Hub during 2008 (EIA, 2008). 

FIGURE 3–2.—Loss in Capacity (MWh) due to Sedimentation 

Weekly weighted average wholesale prices were used to estimate an average 

monthly price used in the analysis as summarized in column three of Table 3–2. 

The average monthly price was applied to the decrease in capacity that may be due 

to increased sedimentation for this particular facility. It is assumed that this facility 

would either experience a reduction in revenue with a decrease in capacity or would 

need to purchase electricity from the wholesale market to meet contract obligations. 

This would likely either result in a loss in sales or an increase in cost to the operator. Table 3–2 represents an estimated value in the loss of this capacity based on 

the assumptions listed above over an 8 month period. 

TABLE 3–2.—ESTIMATED VALUE OF LOST POWER PRODUCTION CAPACITY DUE TO SEDIMENTATION 

Month MWh Reduction Wholesale Price Per MWh Energy Value 

Jan .............................................................................................................. 4,808 $45.17 $217,139 

Feb ............................................................................................................. 1,207 78.00 94,120 

Mar ............................................................................................................. ........................ 67.67 ........................

Apr .............................................................................................................. 274 73.06 20,018 

May ............................................................................................................. ........................ 61.50 ........................

Jun .............................................................................................................. 5,333 53.70 286,400 

Jul ............................................................................................................... 181 93.42 16,862 

Aug ............................................................................................................. 1,374 64.00 87,931 

Total .............................................................................................. 13,176 ........................ 722,470 

4.0 HYDROPOWER 

Hydropower facilities along the Missouri River in North Dakota consist of the 

Garrison Dam and its reservoir, Lake Sakakawea. In addition, hydropower operations in North Dakota are affected by the operation of Oahe Dam in South Dakota 

because Lake Oahe extends into southern North Dakota up to just south of the city 
104 

9 USACE, Northwest Division. Missouri River Mainstem Reservoir System, Master Water 

Control Manual, Missouri River Basin. 2006. 

of Bismarck when the pool is full. Louis Berger completed an evaluation of the potential impacts to hydropower generation at the Garrison facility. The results indicate the only measurable impact of sedimentation on hydropower generation at this 

time is a loss in power production during the colder months of the year due to increased flooding risks. This section will evaluate the economic implications of this 

loss in power production. 

Outflows from Lake Sakakawea at Garrison Dam are commonly through the 

power facilities. The power facilities have a normal capacity of 38,000 cfs and a 

maximum capacity of 41,000 cfs.9 The average outflow is 22,800 cfs, resulting in an 

annual plant factor of approximately 60 percent. The Garrison Dam has a five unit 

power plant with a generating capacity 583.3 MW. This reflects a recent upgrade 

from previously 518 MW (USACE, 2006). 

The benefits of the hydropower facilities along the Missouri River consist of providing dependable energy to meet annual peak power demands of the region. Energy 

generated by these facilities have valuable characteristics that improve the reliability and efficiency of the electric power supply system, such as efficient peaking, 

a rapid rate of unit unloading, and rapid power availability for emergencies in the 

power grid (USACE, 2006). Further, the facilities generate clean energy with a 

minimal carbon-footprint. 

Annual gross power generation at Garrison Dam was on average 2.29 million 

MWh from 1967 (2 years after Lake Sakakawea was filled) through 2007 (Table 4– 

1). During this time, the annual power generation at the dam has ranged from 1.31 

million MWh in 2007 to 3.35 million MWh in 1975. Hydropower generation is highest during the winter heating season (December to mid-February) and in the summer when air-conditioning systems are used (mid-June to early September). 

In general, power generation has decreased over time, largely as a function of decreased runoff in the watershed caused by drought. The exception occurred during 

the mid-1990s when spring snow melt and high rainfall in the Upper Missouri River 

watershed resulted in high power generation rates. In addition, some generation capacity, especially during the winter months, has been lost and sedimentation is 

playing an unquantifiable part. 

To get an understanding to the impacts that may occur with a reduction in hydropower capacity at the Garrison facility during the winter, an analysis was conducted 

on average power production as follows. Water release rates at Garrison Dam for 

ice-in vary from year to year depending on the specific conditions and needs of other 

users. Under ‘‘normal conditions’’, the USACE would release from ‘‘the top of the 

maintenance zone’’ and gradually release the water over the winter. However, reduced runoff in the watershed has resulted in a decline in power generation between 

1967 and 2008 by almost a factor of two. Louis Berger used linear regression to estimate the decline as approximately 8 percent greater during the 5-month-long colder 

period (December to April) than during the other months of the year. Although 

there are other potential causes for a relatively greater decline during the winter 

months (such as the statistical effect of the floods in the mid-1990s), aggradation 

in the Missouri River in the headwater of Lake Oahe have likely contributed to this 

decline but at an unquantifiable level. 
105 

TABLE 4–1.—GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWH) 

YEAR 

MONTH 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

1967 ................................... .................... .................... .................... .................... .................... 232,818 295,092 336,767 237,050 275,633 237,942 241,156 1968 ................................... 252,539 250,001 172,681 196,858 181,466 149,118 156,431 189,139 212,389 290,561 220,158 234,317 1969 ................................... 270,694 273,173 274,214 226,709 220,131 163,022 257,475 282,114 238,412 234,153 234,215 270,807 1970 ................................... 238,768 229,732 184,253 216,135 249,277 249,694 253,971 260,164 202,972 254,324 255,847 226,249 1971 ................................... 278,471 237,686 261,810 310,917 344,378 316,965 332,812 252,987 219,089 227,357 231,432 227,571 1972 ................................... 264,805 246,236 251,070 339,180 355,277 337,281 259,622 223,343 193,055 207,270 207,332 216,580 1973 ................................... 252,601 214,626 235,511 184,710 162,558 175,566 195,675 200,477 182,992 184,094 183,062 216,226 1974 ................................... 239,337 220,615 229,313 173,132 193,606 216,058 250,441 265,274 217,902 274,602 224,294 229,846 1975 ................................... 202,670 228,625 228,566 159,040 300,368 344,928 327,106 346,401 344,051 307,207 301,414 259,895 1976 ................................... 238,366 267,342 241,560 280,298 293,607 337,657 347,855 297,624 241,298 240,857 267,802 222,627 1977 ................................... 261,495 226,827 187,604 145,158 146,577 140,361 161,710 149,503 130,351 116,836 144,514 188,750 1978 ................................... 238,901 223,758 170,809 152,426 147,911 282,902 365,976 359,461 297,607 294,386 288,538 216,800 1979 ................................... 273,286 242,247 243,472 247,986 337,281 326,261 248,273 200,522 161,316 143,923 131,469 185,069 1980 ................................... 211,978 250,217 244,215 180,241 171,693 187,355 242,163 220,382 195,389 205,592 215,010 192,581 1981 ................................... 223,298 221,708 201,301 144,434 157,530 220,945 258,497 211,709 169,211 137,018 134,494 174,483 1982 ................................... 229,612 246,046 230,513 150,534 220,269 205,686 241,775 196,792 165,964 182,936 273,082 214,505 1983 ................................... 195,282 252,410 265,769 202,091 158,451 166,381 171,991 255,878 213,868 133,385 156,472 209,450 1984 ................................... 255,688 234,352 177,212 149,491 133,458 133,898 219,728 268,821 241,132 229,359 235,378 208,485 1985 ................................... 252,369 240,712 177,209 160,436 177,001 188,864 185,625 173,756 156,144 127,688 139,786 199,184 1986 ................................... 235,321 212,537 229,322 170,761 99,653 141,125 188,609 235,182 184,242 214,922 226,168 193,816 1987 ................................... 226,673 231,899 158,323 97,604 148,884 169,561 180,083 178,711 154,063 127,735 122,734 191,642 1988 ................................... 198,547 223,301 175,902 159,051 168,085 166,187 172,799 160,599 117,128 95,739 94,058 159,654 1989 ................................... 163,976 170,372 137,847 130,908 182,384 192,195 198,356 190,547 108,517 95,189 158,685 170,366 1990 ................................... 206,707 148,555 128,636 146,336 164,180 168,175 172,163 158,428 92,532 88,832 96,474 148,656 1991 ................................... 173,156 159,305 103,663 140,304 163,980 161,695 174,731 173,966 118,687 116,791 122,517 166,840 1992 ................................... 196,593 164,598 108,911 136,972 169,802 164,615 172,671 160,192 115,239 86,884 84,653 156,621 1993 ................................... 159,708 104,673 89,163 85,072 134,907 138,487 137,753 149,864 104,769 96,345 102,339 130,855 1994 ................................... 136,453 117,532 115,117 111,526 231,975 216,358 190,774 184,486 150,159 112,592 128,289 180,847 1995 ................................... 199,766 175,462 134,753 111,981 119,587 105,419 137,043 300,487 347,671 353,293 294,565 197,713 1996 ................................... 221,226 191,266 182,434 250,196 290,399 335,550 367,096 359,879 331,570 261,562 197,127 185,159 1997 ................................... 218,714 183,318 153,772 154,629 297,147 360,731 377,870 362,492 359,527 356,377 316,385 199,143 1998 ................................... 197,614 198,563 173,961 170,373 214,778 223,976 219,973 220,021 185,343 146,834 175,793 190,242 1999 ................................... 221,959 217,155 212,825 235,541 236,204 265,232 267,076 260,022 210,046 171,329 154,754 177,371 2000 ................................... 187,146 200,649 163,472 167,992 197,165 209,323 210,979 204,901 151,966 122,592 174,651 153,161 2001 ................................... 159,385 129,011 113,542 103,331 105,408 116,976 121,032 122,385 94,213 85,351 85,865 111,259 
106 

TABLE 4–1.—GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWH)—Continued 

YEAR 

MONTH 

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 

2002 ................................... 111,452 100,760 99,396 86,132 106,810 172,552 179,593 180,714 144,581 118,357 146,246 162,429 2003 ................................... 150,925 164,934 142,549 150,091 155,550 174,755 183,761 177,311 135,844 86,510 93,167 130,288 2004 ................................... 156,136 171,953 132,585 130,906 126,761 140,007 145,470 138,970 116,618 92,022 97,700 119,484 2005 ................................... 118,210 90,236 93,733 129,719 125,240 115,245 125,521 127,459 110,058 100,814 103,473 122,061 2006 ................................... 140,181 109,310 114,305 104,814 122,996 158,479 169,765 176,082 135,781 94,534 99,072 117,784 2007 ................................... 121,942 108,113 112,359 100,052 104,596 125,814 130,747 129,425 90,900 85,512 82,820 117,329 2008 ................................... 117,115 110,226 97,062 92,767 98,124 110,098 114,729 119,052 104,899 .................... .................... ....................

TABLE 4–1 (CONTINUED).—GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWH) 

Year 

FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 

MIN MAX TOTAL MEAN MIN MAX Mean 

1967 ................................................................................................................................................................. 232,818 336,767 .................... .................... 172,681 252,539 222,647 1968 ................................................................................................................................................................. 149,118 290,561 2,505,658 208,805 226,709 274,214 255,821 1969 ................................................................................................................................................................. 163,022 282,114 2,945,119 245,427 184,253 270,807 227,939 1970 ................................................................................................................................................................. 184,253 260,164 2,821,386 235,116 226,249 310,917 263,027 1971 ................................................................................................................................................................. 219,089 344,378 3,241,475 270,123 227,571 339,180 265,772 1972 ................................................................................................................................................................. 193,055 355,277 3,101,051 258,421 184,710 252,601 220,806 1973 ................................................................................................................................................................. 162,558 252,601 2,388,098 199,008 173,132 239,337 215,725 1974 ................................................................................................................................................................. 173,132 274,602 2,734,420 227,868 159,040 229,846 209,749 1975 ................................................................................................................................................................. 159,040 346,401 3,350,271 279,189 238,366 280,298 257,492 1976 ................................................................................................................................................................. 222,627 347,855 3,276,893 273,074 145,158 261,495 208,742 1977 ................................................................................................................................................................. 116,836 261,495 1,999,686 166,641 152,426 238,901 194,929 1978 ................................................................................................................................................................. 147,911 365,976 3,039,475 253,290 216,800 273,286 244,758 1979 ................................................................................................................................................................. 131,469 337,281 2,741,105 228,425 180,241 250,217 214,344 1980 ................................................................................................................................................................. 171,693 250,217 2,516,816 209,735 144,434 223,298 196,664 1981 ................................................................................................................................................................. 134,494 258,497 2,254,628 187,886 150,534 246,046 206,238 1982 ................................................................................................................................................................. 150,534 273,082 2,557,714 213,143 195,282 265,769 226,011 1983 ................................................................................................................................................................. 133,385 265,769 2,381,428 198,452 149,491 255,688 205,239 1984 ................................................................................................................................................................. 133,458 268,821 2,487,002 207,250 160,436 252,369 207,842 1985 ................................................................................................................................................................. 127,688 252,369 2,178,774 181,565 170,761 235,321 209,425 1986 ................................................................................................................................................................. 99,653 235,321 2,331,658 194,305 97,604 231,899 181,663 
107 

1987 ................................................................................................................................................................. 97,604 231,899 1,987,912 165,659 159,051 223,301 189,689 1988 ................................................................................................................................................................. 94,058 223,301 1,891,050 157,588 130,908 170,372 152,551 1989 ................................................................................................................................................................. 95,189 198,356 1,899,342 158,279 128,636 206,707 160,120 1990 ................................................................................................................................................................. 88,832 206,707 1,719,674 143,306 103,663 173,156 145,017 1991 ................................................................................................................................................................. 103,663 174,731 1,775,635 147,970 108,911 196,593 154,783 1992 ................................................................................................................................................................. 84,653 196,593 1,717,751 143,146 85,072 159,708 119,047 1993 ................................................................................................................................................................. 85,072 159,708 1,433,935 119,495 111,526 136,453 122,297 1994 ................................................................................................................................................................. 111,526 231,975 1,876,108 156,342 111,981 199,766 160,562 1995 ................................................................................................................................................................. 105,419 353,293 2,477,740 206,478 182,434 250,196 208,567 1996 ................................................................................................................................................................. 182,434 367,096 3,173,464 264,455 153,772 218,714 179,118 1997 ................................................................................................................................................................. 153,772 377,870 3,340,105 278,342 170,373 199,143 187,931 1998 ................................................................................................................................................................. 146,834 223,976 2,317,471 193,123 190,242 235,541 215,544 1999 ................................................................................................................................................................. 154,754 267,076 2,629,514 219,126 163,472 200,649 179,326 2000 ................................................................................................................................................................. 122,592 210,979 2,143,997 178,666 103,331 159,385 131,686 2001 ................................................................................................................................................................. 85,351 159,385 1,347,758 112,313 86,132 111,452 101,800 2002 ................................................................................................................................................................. 86,132 180,714 1,609,022 134,085 142,549 164,934 154,186 2003 ................................................................................................................................................................. 86,510 183,761 1,745,685 145,474 130,288 171,953 144,374 2004 ................................................................................................................................................................. 92,022 171,953 1,568,612 130,718 90,236 129,719 110,276 2005 ................................................................................................................................................................. 90,236 129,719 1,361,769 113,481 104,814 140,181 118,134 2006 ................................................................................................................................................................. 94,534 176,082 1,543,103 128,592 100,052 121,942 112,050 2007 ................................................................................................................................................................. 82,820 130,747 1,309,609 109,134 92,767 117,329 106,900 2008 ................................................................................................................................................................. 92,767 119,052 .................... .................... .................... .................... ....................
108 

10 ‘‘The Missouri River: A View from Upstream’’, Prairie Fire Newspaper, December 2007, 

http://www.prairiefirenewspaper.com/print/178. 

The value of lost power production was estimated as follows. Table 4–2 shows the 

monthly average hydropower production during the cold months during two points 

in time. This includes 1968 and 1972 after the dam was operational and 2003 and 

2007, the last years that data are available. The average for the cold months for 

each of these periods is shown in the last row of the table and indicates that production has declined by nearly 50 percent. 

TABLE 4–2.—MONTHLY MEAN HYDROPOWER PRODUCTION FROM THE GARRISON DAM 

Year 

Cold Month (Dec.–April) Mean Hydropower Production 

Mean Monthly 

Production Year Mean Monthly Production 

1968 ........................................................................................................... 225,821 2003 144,374 

1969 ........................................................................................................... 227,939 2004 110,276 

1970 ........................................................................................................... 263,027 2005 118,134 

1971 ........................................................................................................... 265,772 2006 112,050 

1972 ........................................................................................................... 184,710 2007 106,900 

5-yr Average (MWh) ................................................................................... 233,454 ........................ 118,347 

Table 4–3 shows the reduction in mean power production between the two time 

periods. These differences were extrapolated to calculate a loss in power production 

over the 5 month cold period as shown in column 3. In other words, on average 

power production has declined be over 570,000 MWh during the cold months between the late 1960s and the present. 

TABLE 4–3.—DIFFERENCE IN HYDROPOWER PRODUCTION 

Mean Cold Month Generation 

(MWh) 

Total Average 

Production During Cold Months 

(MWh) 

1968–1972 .............................................................................................................................. 233,454 1,167,269 

2003–2007 .............................................................................................................................. 118,347 591,734 

Difference ................................................................................................................... 115,107 575,535 

Because it is uncertain how much aggradation in downstream reaches is contributing to flooding and reduced flows from the Garrison Dam during colder months, 

several scenarios were developed to provide some insight on the potential economic 

impacts to hydropower production. The results are shown in Table 4–4. The top of 

the table shows electricity generation reduction scenarios which range from 10 to 

100 percent. 

As mentioned earlier, Western markets and transmits the power generated at the 

dam at cost to non-profit preference power entities. While the cost of hydropower 

production does not change over the year, the value of the power produced varies 

due to changes in demand with the highest demand occurring in the summer and 

winter. Therefore, the impacts of a reduction in electricity generation would not 

occur to Western but to its customers if it is unable to meet power demands. This 

issue has been raised most recently in relation to Western’s inability to meet power 

commitments due to drought conditions. For instance, between 2004 and 2007, rates 

to wholesale customers increased by 37.3 percent to cover cost of power purchased 

off the open market due, in part, to reduced reservoir levels.10

To value of the loss in electricity generation at the Garrison Dam, a price differential was applied to the capacity losses as discussion above. The price differential 

represents the difference in cost of production to Western and the average weighted 

monthly wholesale prices for winter months discussed in Section 3.0. The difference 

thus represents a higher cost alternative for power reduction than hydropower. 

The results are summarized in Table 4–4. Under a low impact scenario, electricity 

generation capacity would decline by 10 percent or 57,000 MWh. Assuming a price 

differential of $27/MWh, the cost to replace this capacity with an alternative is $1.5 

million per year. Under a high impact scenario, with the greatest reduction in hydropower capacity due to various factors and the highest price differential, losses 

could reach as much as $34.5 million per year. 
109 

TABLE 4–4.—ESTIMATED VALUE OF POWER PRODUCTION SCENARIOS 

Percentage Reduction in Hydropower (MWh) 

10 percent 

(57,554) 

25 percent 

(143,884) 

50 percent 

(287,768) 

75 percent 

(431,651) 

100 percent 

(575,535) 

Value of Lost Production (Sales)—$27/MWh ..... $1,553,945 $3,884,861 $7,769,723 $11,654,584 $15,539,445 

Value of Lost Production (Sales)—$42/MWh ..... 2,417,247 6,043,118 12,086,235 18,129,353 24,172,470 

Value of Loss Production (Sales)—$60/MWh ..... 3,453,210 8,633,025 17,266,050 25,899,075 34,532,100 

5.0 RECREATION 

Water based recreation, especially sport fishing, has a very important role in 

North Dakota’s economy. A recent study by North Dakota State University estimated that the total gross business volume generated by fishing on Lake 

Sakakawea alone was as high as $89 million per year. Thus, changes in the reservoirs or river reaches due to sedimentation and erosion have potential significant 

economic implications. The economic evaluation will utilize the results of subtask 

5C which evaluated the impacts of siltation on recreation in North Dakota. 

Under Task 5A, Berger identified areas of the river impacted most by the accumulation of sediments and occur approximately 10 to 15 miles downstream from the 

upstream end of the lake zones (Lake Sakakawea and Lake Oahe) created by the 

Garrison and Oahe Dams. Most of the sediment accumulation is concentrated within 

a 30-mile reach of these points. Under Task 5C, Berger identified recreational sites 

that are located within the areas impacted by sedimentation as summarized in Figure 5–1. According to the sediment aggradation maps, nearly all of the intensive use 

recreation sites on Lake Sakakawea are in areas of low to moderate sedimentation 

levels. On Lake Oahe, Graner Park Recreation Area and Kimball Bottom Recreation 

Area are areas of intense recreational use that are affected by high levels of sedimentation. MacLean Bottom Recreation Area is also identified as an area with high 

sedimentation levels but the site is considered a low density recreation area. In all, 

1.1 million visitors recreated at sites within areas identified as either ‘‘low’’ or ‘‘moderate’’ areas of sediment aggradation on Lake Sakakawea and an additional 2.3 million visitors recreated at similarly identified sites in Lake Oahe according to the 

aggradation maps. 

FIGURE 5–1.—Developed Recreational Sites within Aggradation Areas 

Sedimentation can negatively affect recreation resources in two ways: 

—Direct.—Affecting access or pathways within the reservoirs which impact visitors ability to access or utilize the water, compromising their safety, or affecting 

the aesthetic environment, or 
110 

11 USACE, Missouri River Master Water Control Manual, Final Environmental Impact Statement, March 2004. 

—Indirect.—Affecting physical properties within the reservoirs which in turn affect aspects of the recreationists overall trip (e.g., important fish habitat which 

would affect the recreational fishery). 

Loss of either access or declines in sport fishing would have negative consequences on recreators coming to the area for these activities. This can lead to economic impacts but will depend on how recreators react to changing conditions. For 

instance, if sedimentation reduces access to certain boat ramps at the river or reservoirs but recreators can utilize alternative sites for access the number of visitor 

days may or may not decline. Recreators may need to incur higher costs to recreate 

in the area due to traveling farther to gain access to the site. However, this reaction 

will not have a negative impact on the regional or State economy though it may 

have some negative impacts to local areas where high sedimentation is occurring. 

Louis Berger was unable to find any studies that have evaluated how recreators 

would change their behaviors in reaction to sedimentation levels. Thus, it is unknown how sedimentation may cause economic impacts to the recreation industry. 

5.1 Impacts to Boat Ramps 

Erosion and transport of silts and sediments into Lakes Sakakawea and Oahe can 

result in the aggradation near boat ramps posing problems to users and rendering 

them unusable. Dredging the ramps is currently performed when access is blocked 

by sediment build up on and around ramps; however this poses an ongoing maintenance cost to monitor and remove the sediments to keep ramps open. Complicating 

the management of sediment bound boat ramps are the lake levels. Severe drought 

in the recent past has resulted in very low lake levels which leaves some ramps out 

of the water or the ends of the ramps a long distance from the parking area. Sediment aggradation and boat ramp closures in areas with few points of access would 

cause additional strain as the cost to remove the sediment may outweigh the benefit 

of clearing the ramp resulting in ramp closures. Ramp closures in remote locations 

around the study area would force visitors to drive further to launch a boat. In some 

areas, building a new ramp nearby is more cost effective than dredging existing 

ramps. 

The USACE provides high, mid, and low water ramps at many of the access areas 

to accommodate changes in reservoir levels which also provide alternative access 

during periods when ramps are covered with sediment. Most recently Fort Stevenson State Park, Government Bay, and Sanish Bay were locations within the reservoir that required dredging to provide boater access. The Fort Stevenson West 

Ramp was closed because it is entirely silted in and a brand new marina ramp is 

being constructed on the northwest side of the bay. Fort Stevens State Park is approximately 3 miles south of the town of Garrison; however it is not known if sediment is being loaded into the arm from tributary or in-reservoir sources. The Government Bay low water ramp was completely reconstructed within the last year because of siltation problems as the bay is filling up with silt and there is no longer 

a good location for moving the boat ramp. Complicating matters, the ramp cannot 

be extended because of a lack of room. In general, USACE’s recent solution has been 

to move or extend ramps rather than continue to dredge out areas, because it is less 

expensive. These areas are within bays or smaller arms that are subject to local 

sedimentation processes and were not identified as areas of aggradation by Berger 

under Task 5A that focused on changes in the elevations within the main channel 

and thalweg. 

6.0 WATER SUPPLY AND IRRIGATION INTAKES 

Review of documents and studies has revealed that an increase in sedimentation 

along the river is impacting water intakes for municipalities, irrigation, commercial 

and industrial customers. According to the Missouri River Master Manual 11 there 

are over 500 water intakes along Lake Sakakawea and the Garrison Reach of the 

Missouri River in North Dakota. Table 6–1 summarizes the number and type of intakes by location. 

TABLE 6–1.—WATER INTAKE LOCATIONS ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Location Power Municipal Industrial Irrigation Domestic Public Total 

Lake Sakakawea ............................ 1 10 (5) 6 (1) 44 (10) 228 (63) 11 300 (79) 
111 

TABLE 6–1.—WATER INTAKE LOCATIONS ALONG THE MISSOURI RIVER IN NORTH DAKOTA— 

Continued 

Location Power Municipal Industrial Irrigation Domestic Public Total 

Garrison Reach .............................. 6 3 6 77 28 3 123 

Source.—USACE, Missouri River Master Water Control Manual, Final Environmental Impact Statement, Table 3.10.1, p. 3–112, March 2004. 

( ) Denotes intakes on Reservation Lands. 

Berger further evaluated potential impacts to water intakes from sedimentation. 

Given that 77 percent of total water use in North Dakota is for power generation, 

impacts to these facilities are addressed separately in Section 3.0. In addition, 

Berger conducted interviews with the city of Mandan Water Department and the 

Public Works Director of the city of Williston to learn about potential impacts to 

municipal water intakes from sedimentation. Both entities indicated that they have 

been impacted by increased sedimentation. The city of Mandan’s water intake has 

been impacted by both increases in sedimentation and vegetation. The city shares 

the intake with the Tesoro Refinery. Both parties have spent several thousands of 

dollars keeping the intake free of debris. This includes $150,000 to dredge one-half 

mile of the river 5 years ago and $20,000 to hire a diver to remove silt from the 

intake in April 2007. They are expecting that additional maintenance will be needed 

in another 2 years. 

The city of Williston originally operated three water intakes from the Missouri 

River as the city’s sole source of water. Two of these intakes became completely covered with silt and in 2003 the city received $2.0 million from the EPA to develop 

an alternative water line. 

The interviewees indicated that Trenton Indian Service Area, which is controlled 

by Turtle Mountain, and the Heskett Plant are also experiencing impacts to intakes 

due to sedimentation or increased vegetation. However, Berger was unable to reach 

any representatives from these entities to confirm these statements. 

In addition to these uses, 121 intakes are used for agricultural irrigation which 

helps to increase crop yields or grow crops that could not be grown in this region. 

Most of these irrigation intakes are portable and placed to access water at a low 

cost. However, operators may be impacted by higher operating costs, loss in efficiency or increases in maintenance related to sedimentation issues. 

To get an understanding of how many irrigation intakes may be affected by sedimentation along the Missouri River in North Dakota, Berger obtained location data 

of all the irrigation intakes from the USACE and plotted these locations on the 

aggradation maps created under Task 5A. Each intake located within one-half mile 

of the aggradation areas was identified as being potentially impacted by sedimentation. The analysis showed that 100 intakes were located within defined aggradation 

areas. Of these 100 intakes, most were located in either ‘‘low’’ or medium 

aggradation areas while five were located in a ‘‘high’’ aggradation area (Table 6– 

2). It is not known at this time how intakes within the different aggradation areas 

may be impacted by sedimentation though it is likely that operators in areas of high 

aggradation will be impacted more severally than those in moderate or low areas. 

TABLE 6–2.—INTAKES WITHIN INDENTIFIED AREAS OF AGGRADATION 

Level of Aggradation Number of Intakes 

Low ....................................................................................................................................................................... 48 

Moderate ............................................................................................................................................................... 47 

High ...................................................................................................................................................................... 5 

7.0 CONCLUSIONS 

Under this Task, Berger evaluated the potential impacts to different resources 

and activities from sedimentation and what consequences these impacts would have 

to Federal, tribal, State, regional economies. It appears that the most significant impact is from increased flooding in and around Bismarck and Mandan especially in 

the winter. Other resources and activities are also experiencing impacts such as 

electric power production (hydro and thermal), recreation, water supply and land 

use. However none of these impacts appear as significant as flood control. The report was unable to quantify impacts to recreation and agricultural use and would 

suggest these resources be studied further. In addition, data and costs may become 
112 

available associated with operational and maintenance impacts for infrastructure 

impacted by sedimentation. 

The results of the analysis are summarized in Table 7–1. 
113 

TABLE 7–1.—POTENTIAL ECONOMIC IMPACTS OF SEDIMENTATION ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Resource Potential Impact 

Impact to Economy 

Timeframe Comments 

Federal State Local Tribal 

Agricultural Land Use ............... Loss of Productivity of Ag Lands ............................ ............ ............ X X Short Term .......Flood Control ............................. Increased Flooding ................................................... ............ X X ............ Long-term ........ Increased flooding potential can lead to costly buy outs, increased insurance costs and reduction in property values. Coal-Fired Power Plants ............ Reduction in generation capacity ........................... ............ ............ X ............ Long-term ........ Loss in revenue or increase in costs to meet contract demands. Hydropower ................................ Reduction in generation capacity ........................... ............ X X X Long-term ........ Increased flooding potential can reduce hydropower production; 

especially during colder months. 

Recreation ................................. Increased maintenance costs for recreational facilities. ............ X X X Long-term ........ Increased cost to dredge and maintain facilities affected by sedimentation. Impacts to visitor behavior are unknown. Water Supply ............................. Increase operation and maintenance costs ............ ............ ............ X X Long-term ........ Small number of intakes are impacted by sedimentation causing an increase in operation and maintenance costs. 
114 

References 

Energy Information Agency, Wholesale Market Data, Cinergy Hub 2008, accessed 

at http://www.eia.doe.gov/cneaf/electricity/wholesale/wholesale.html. 

FEMA. September 1985. Flood Insurance Study—City of Bismarck, North Dakota 

Burleigh County. Community Number 380149. Federal Emergency Management 

Agency. 

FEMA. September 1985. Flood Insurance Study—Burleigh County, North Dakota 

Unincorporated Areas. Community Number 380017. Federal Emergency Management Agency. 

FEMA. July 2005. Flood Insurance Study—Burleigh County, North Dakota and 

Incorporated Areas. FIS Number 38015CV000A. Federal Emergency Management 

Agency. 

FEMA. National Flood Insurance Program, Flood Insurance Manual, May 2008, 

Revised October 2008. Accessed at http://www.fema.gov/pdf/nfip/manual200810/ 

coverl102008.pdf. 

Remus, John, Personal Communication, November, 2008. 

‘‘The Missouri River: A View from Upstream’’, Prairie Fire Newspaper, December 

2007, http://www.prairiefirenewspaper.com/print/178. 

USACE, Missouri River Master Water Control Manual, Final Environmental Impact Statement, March 2004. 

USDA National Agricultural Statistics Service (NASS) Cropland Data Layer for 

Midwestern/Prairie States, 2007. 

USACE, Omaha District, Garrison Dam/Lake Sakakawea Master Plan with Integrated Programmatic Environmental Assessment, Missouri River, North Dakota, 

Update of Design Memorandum MGR–107D, December 14, 2007. 

USACE, Northwest Division. Missouri River Mainstem Reservoir System, Master 

Water Control Manual, Missouri River Basin. 2006. 

APPENDIX C—IMPACTS OF SILTATION OF THE MISSOURI RIVER ON RECREATION IN

NORTH DAKOTA

1.0 INTRODUCTION 

The Missouri River flows for approximately 410 miles through North Dakota providing a multitude of recreation opportunities for residents and visitors alike. Lakes 

Sakakawea and the upper 70 miles of Lake Oahe supply approximately 430,000 

acres of flat water boating opportunities between these two reservoirs. The study 

area includes an area of the Missouri River from the Montana border to the upstream end of Lake Sakakawea, which can extend past Williston to just south of 

Bismarck at full pool, and also approximately 80 miles of riverine conditions from 

Garrison Dam to the upstream end of Lake Oahe (Garrison reach). In the summer, 

recreational opportunities in the area consist of boating, fishing, hunting, camping, 

hiking, horseback riding, wildlife viewing, swimming, and sunbathing. In the winter, activities such as snowmobiling and ice fishing are common in this area. 

North Dakota contains one dam, Garrison Dam, and its associated reservoir, Lake 

Sakakawea. The reservoir known as Lake Oahe, formed by the Oahe Dam in South 

Dakota, also extends into North Dakota from the south. Therefore, from a recreation 

perspective the Missouri River in North Dakota may be thought of as having four 

parts: 

—The Williston Reach.—The riverine segment close to the Montana border, into 

which the Yellowstone River flows, and which flows into Lake Sakakawea. This 

reach can become inundated by Lake Sakakawea at full pool; 

—Lake Sakakawea.—The reservoir formed by Garrison Dam (finished in 1953), 

whose entire surface is within the State of North Dakota; 

—The Garrison Reach.—The riverine segment from Garrison Dam to the headwaters of Lake Oahe; and 

—Lake Oahe.—The reservoir formed by Oahe Dam in South Dakota (closed in 

1958), and which is in both North Dakota and South Dakota. 

These four separate regions will be used to describe impacts to recreation from 

siltation of the Missouri River in North Dakota. 

2.0 LITERATURE AND DATA COLLECTION METHODOLOGY 

Several types of information were used to meet study objectives, including (1) 

interviews with experienced recreation managers and (2) a review of existing documents. Key recreation personnel were contacted from the following institutions: 

—North Dakota Game and Fish 

—North Dakota Park and Recreation Department 

—North Dakota Water Commission 

—North Dakota State University 
115 

1http://www.nodakoutdoors.com/valleyoutdoors5.php. 

2http://news.minnesota.publicradio.org/features/2003/07/03lgundersondlriverrecreation/. 

—City of Williston 

—Bismarck Parks and Recreation District 

—Ford Abraham Lincoln State Park 

—United States Army Corps of Engineers, Omaha District 

A list of recreation issues, sites, and documents were derived from the interviews 

and incorporated into the evaluation. In addition, Federal, State, and local agencies 

in the recreation resources arena were contacted for literature detailing recreation 

opportunities, policies, planning efforts, use levels, and attitudes related to recreation on the Missouri River. The following reports, documents, and Web sites were 

reviewed for information related to recreation, erosion, and siltation related to the 

study objectives: 

—Quarterly Drought Reports from the, (USACE—Omaha District, 2008). 

—North Dakota State Comprehensive Outdoor Recreation Plan 2008–2012, (DH 

Research, the North Dakota Recreation and Parks Association and the North 

Dakota Parks and Recreation Department). 

—Missouri River Mainstem Reservoir System Master Water Control Manual Missouri River Basin (Reservoir Control Center, USACE—Northwestern Division, 

2006). 

—A Reference Guide to Water in North Dakota (North Dakota Water Commission, 2005) The Valley Outdoors: Lake Sakakawea in Peril 1 (Leier, 2004). 

—Minnesota Public Radio, Water Wars: Recreation on the Missouri River 

(Gunderson, July 2, 2003).2

3.0 RECREATION OPPORTUNITIES 

The Missouri River accounts for 80 percent of the total streamflow in the State 

(USGS 2008) and also provides significant water based recreation opportunities. 

Recreation facilities along the river vary from game lands, State parks, municipal 

parks, Native American owned and operated facilities, and private access, to primitive dispersed areas. Figure 3–1 shows the location of the 56 formal recreation areas 

along the river in the study area, while Table 3–1 contains the names of the access 

points on the figure and summarizes the amenities at the site and the agency/entity 

responsible for managing the site. 

(Source: USACE 2008a, as modified by staff) 

FIGURE 3–1.—Developed Recreation Facilities Along the Missouri River in North 

Dakota 
116 

TABLE 3–1.—AMENITIES AT EACH DEVELOPED RECREATION FACILITY ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Location/Manager ID 

Amenities at Each Recreation Facility 

Boat 

Ramp 

Boat 

Dock 

Boat 

Rental 

Boat 

Storage Camping Cabin Rental Electric Hookup Drinking Water Showers Restrooms Picnic Shelter Picnic Tables Swim Beach Playground Restaurant/ Concession Boat Fuel Dump Station Fishing Cleaning Station 

Lake Trenton/WCWRD ..................... 1 X X ............ .............. X ............ X X X X X X X X X ........ X X Little Muddy/WCWRD ...................... 2 X ........ ............ .............. ............ ............ ................ ................ .............. X X X .......... .................... ...................... ........ .............. ................American Legion Park/American 

Legion ........................................ 3 X ........ ............ .............. X ............ X X .............. X X X .......... .................... ...................... ........ .............. ................

Lewis and Clark State Park/State 

of ND ......................................... 4 X X X X X ............ X X X X X X X X X X X X 

White Tail Bay (Lund’s Landing)/ 

WCWRD ...................................... 5 X X ............ .............. X X ................ X X X X X .......... .................... X ........ .............. ................

Tobacco Gardens/McKenzie Co. 

Park Board ................................. 6 X X ............ .............. X X X X X X X X .......... X X X X X 

Little Egypt/WCWRD ....................... 7 ........ ........ ............ .............. X ............ ................ ................ .............. X X X .......... .................... ...................... ........ .............. ................Little Beaver Bay/Williams County 

Water Resource District (WCWRD) .................................... 8 X X ............ .............. X ............ ................ ................ .............. X X X .......... .................... ...................... ........ .............. ................

White Earth Bay/Mountrail County 

Park Board ................................. 9 X X ............ .............. X ............ ................ X X X X X .......... .................... X ........ X X 

Four Bears/Three Affiliated 

Tribes ......................................... 10 X X ............ .............. X ............ ................ X .............. X X .............. .......... .................... X X X X 

New Town/New Town Park Board .. 11 X X ............ X X X X X X X X X .......... X X X X X Reunion Bay (Sanish Bay)/New 

Town Park Board ....................... 12 X X ............ .............. ............ ............ ................ ................ .............. .................. .............. .............. .......... .................... ...................... ........ .............. ................

Skunk Creek/Three Affiliated 

Tribes ......................................... 13 X ........ ............ .............. X X ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................

Pouch Point/Three Affiliated 

Tribes ......................................... 14 X X ............ .............. X ............ X X X X X X .......... .................... X ........ .............. ................

Van Hook/Mountrail County Park 

Board ......................................... 15 X X ............ X X X X X X X X X .......... X X X X X 

Parshall Bay/Mountrail County 

Park Board ................................. 16 X X X .............. X X X X X X X X .......... X X X X X 

Deepwater Creek/USACE ................ 17 X X ............ .............. X ............ ................ X .............. X X X .......... .................... ...................... ........ .............. ................McKenzie Bay/Watford City Park 

Board ......................................... 18 X X X X X X X X X X X X .......... X X X X X 
117 

Charging Eagle/Three Affiliated 

Tribes ......................................... 19 X ........ ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................

Little Missouri Bay (now closed)/ 

USACE ........................................ 20 X ........ ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................

Indian Hills/State of ND & Three 

Affiliated Tribes ......................... 21 X X X X X X X X X X .............. X .......... .................... X X X X 

Twin Buttes/Three Affiliated 

Tribes ......................................... 22 ........ ........ ............ .............. X ............ X ................ .............. X X X X .................... ...................... ........ .............. ................

Beaver Creek Bay/Zap Park 

Board ......................................... 23 X X ............ .............. X ............ ................ ................ .............. X X X .......... .................... ...................... ........ .............. ................

Lake Shore Park (DakotaWaters)/ 

Beulah Park Board .................... 24 X X ............ X X X X X X X X X .......... X X X X X 

Beulah Bay/Beulah Park Board ..... 25 X X ............ .............. X X X X X X X X .......... .................... ...................... ........ X X Hazen Bay (Walleye Bay)/Hazen 

Park Board ................................. 26 X X ............ .............. X X X X X X X X .......... .................... ...................... ........ X X 

Douglas Creek/USACE .................... 27 X X ............ .............. X ............ ................ X .............. X .............. X .......... .................... ...................... ........ .............. ................Lake Sakakawea State Park/State 

of ND ......................................... 28 X X X X X X X X X X X X X X X X X X 

Ft. Stevenson State Park/State of 

ND .............................................. 29 X X X X X X X X X X X X X X X X X X 

Sportsmen’s Centennial Park/ 

McLean County .......................... 30 X X ............ .............. X ............ X X X X X X X X X ........ .............. X

West Totten Trail/McLean County .. 31 X X ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................East Totten Trail/USACE ................ 32 X X ............ .............. X ............ X X .............. X .............. X .......... .................... ...................... ........ X X Wolf Creek/USACE .......................... 33 X X ............ .............. X ............ ................ X .............. X X X .......... X ...................... ........ X X Government Bay/USACE ................. 34 X X ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. X Riverdale Overlook/USACE .............. 35 ........ ........ ............ .............. ............ ............ ................ ................ .............. .................. X X .......... .................... ...................... ........ .............. ................Spillway Overlook/USACE ............... 36 ........ ........ ............ .............. ............ ............ ................ ................ .............. X X X .......... .................... ...................... ........ .............. ................Tailrace (Missouri River Ramp)/ 

USACE ........................................ 37 X X ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. X 

Tailrace West/USACE ...................... 38 ........ ........ ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................Downstream Campground/USACE .. 39 ........ ........ ............ .............. X ............ X X X X .............. X .......... X ...................... ........ X ................Spillway Pond/USACE ..................... 40 X ........ ............ .............. ............ ............ ................ X .............. X X X X X ...................... ........ .............. ................General Sibley Park/city of Bismarck ......................................... 41 X ........ ............ .............. X ............ X X X X X X .......... X ...................... ........ .............. ................Sibley Nature Park (Trail)/city of 

Bismarck .................................... 42 ........ ........ ............ .............. ............ ............ ................ ................ .............. .................. .............. .............. .......... .................... ...................... ........ .............. ................

Little Heart/Morton County ............. 43 X ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................Kimball Bottom/Burleigh County ... 44 X ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................
118 

TABLE 3–1.—AMENITIES AT EACH DEVELOPED RECREATION FACILITY ALONG THE MISSOURI RIVER IN NORTH DAKOTA—Continued 

Location/Manager ID 

Amenities at Each Recreation Facility 

Boat 

Ramp 

Boat 

Dock 

Boat 

Rental 

Boat 

Storage Camping Cabin Rental Electric Hookup Drinking Water Showers Restrooms Picnic Shelter Picnic Tables Swim Beach Playground Restaurant/ Concession Boat Fuel Dump Station Fishing Cleaning Station 

Kimball Bottom ORV/Burleigh 

County ........................................ 45 ........ ........ ............ .............. ............ ............ ................ ................ .............. .................. .............. .............. .......... .................... ...................... ........ .............. ................

Graner Park/Morton County ............ 46 X ........ ............ .............. X ............ ................ ................ .............. X .............. X .......... X ...................... ........ .............. X MacLean Bottom/State of ND ........ 47 X ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................Fort Rice/Morton County ................ 48 X ........ ............ .............. X ............ ................ ................ .............. X .............. X .......... .................... ...................... ........ .............. X Hazelton/USACE .............................. 49 X ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. X Badger Bay/USACE ......................... 50 ........ ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................Walker Bottom/Standing Rock 

Sioux Tribe ................................. 51 ........ ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................

Beaver Creek/USACE ...................... 52 X ........ ............ .............. X ............ X X X X X X X X ...................... ........ X X Fort Yates/Standing Rock Sioux 

Tribe ........................................... 53 X ........ ............ .............. ............ ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. ................

Cattail Bay/USACE ......................... 54 X ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. X Langelier Bay/Emmons County ...... 55 X ........ ............ .............. X ............ ................ ................ .............. X .............. .............. .......... .................... ...................... ........ .............. X State Line/Emmons County ............ 56 X ........ ............ .............. ............ ............ ................ ................ .............. .................. .............. .............. .......... .................... ...................... ........ .............. ................

(Source: USACE 2005, USACE 2003, as modified by staff.) 
119 

3 Visitor hour is defined as the presence of one or more persons on an area of land or water 

for the purpose of engaging in one or more recreation activities during continuous, intermittent, 

or simultaneous periods of time aggregating to 60 minutes. Visitor-hour incorporates both the 

number of participants and duration of use and provides an estimate on the ‘‘amount’’ of use 

(USACE (Oahe Master Plan) 2007). 

In addition to traditional water based opportunities, recreation and visitors enjoy 

a number of other cultural and historical sites and wildlife areas which are located 

on the river. A list of these sites is provided in Appendix A. 

3.1 Williston Reach 

The Missouri River between the Montana border and the upstream end of Lake 

Sakakawea is generally referred to as the Williston reach. This approximately 60 

mile section of the Missouri River is not inundated by a reservoir and the confluence 

with the Yellowstone River is within this reach. From a recreational perspective, the 

Williston reach is remote and access is limited to two boat ramps; one at the confluence with the Yellowstone River and the other about 25 miles down river at the 

Highway 85 bridge in Williston, North Dakota (not shown on the map). Boating and 

angling are common activities within this reach. 

3.2 Lake Sakakawea 

Lake Sakakawea is the largest reservoir in North Dakota and as such provides 

the greatest amount of flat water recreation opportunities in the State. There are 

forty formal public access areas adjacent to the reservoir of which 37 provide boater 

access (boat ramps). In addition to the public recreation facilities, access is provided 

from private lands, camps, commercial marinas, and other commercial recreational 

facilities (e.g., private campgrounds). 

Lake Sakakawea is also North Dakota’s largest recreational fishery, followed by 

Lake Oahe. Popular sport fish at these two reservoirs include walleye, salmon, 

northern pike, sauger, white bass, and channel catfish. Anglers also participate in 

ice fishing, shoreline fishing, boat fishing, and dark-house spearing and take advantage of the cold-water (salmon), cool-water (especially walleye), warm-water and 

riverine fishery opportunities (USACE 2007). Some of the boating is fishery-related; 

however, other reservoir activities include motorboating, sailboating, waterskiing, 

jetskiing, tubing, and wind surfing. Shoreline day uses and off road vehicle (OHV) 

use are popular at the reservoirs; however, high water levels can eliminate the conditions necessary to participate in these activities. 

3.3 Garrison Reach 

Aside from the Williston reach, the Garrison reach, is the only other section of 

the river in North Dakota that is not inundated by a reservoir. This approximately 

80 mile reach is however controlled by releases from Garrison Dam. There are 11 

boat ramps within this reach and although river levels do fluctuate, the river is 

rarely to low to canoe (USGS, 2008). The river provides water-based recreation including boating, boating-related activities, and swimming. However, sport fishing is 

a primary component of recreation along this section of the river. Swift currents 

along the Missouri River between Garrison Dam and Bismarck are popular with experienced canoeists; while nature lovers enjoy wildlife viewing for bald and golden 

eagles, osprey, beaver, and deer (USACE 2006). 

3.4 Lake Oahe 

Lake Oahe is the second largest reservoir in North Dakota and as such recreation 

is typically water based with boating and fishing the most popular activities. Recent 

drought conditions have changed the upstream reservoir sections from flat water 

(typically at elevations above 1,600–1,608 ft msl) to riverine characteristics which 

could affect the types of activities occurring within this section of the study area 

or leave boat ramps unusable altogether. 

4.0 CURRENT RECREATIONAL USE 

The USACE monitors recreation use activity throughout the study area. The 

amount of estimated use at formal and dispersed sites within the study area is summarized by general area below. 

4.1 Lake Sakakawea 

In 2008, the USACE found that recreation use levels, including dispersed recreation, at Lake Sakakawea consisted of over thirteen million visitor hours.3 Of that 

total, dispersed recreation is estimated to account for over 2 million visitor hours 

on Lake Sakakawea. According to USACE data, recreation sites that received the 

most visitor hours include: Van Hook with over 1 million visitor hours, game man-
120 

agement lands with nearly 1 million visitor hours, Fort Stevenson State Park accounting for about 950,000 visitor hours, Lake Sakakawea State Park with approximately 720,000 visitor hours, East Totten Trail with nearly 700,000 visitor hours, 

and Lake Shore Park with over 575,000 visitor hours. Table 4–1 shows USACE visitor use estimates (actual users) for 40 formal and combined dispersed use areas 

around the lake for the years 2005 to 2008. 

TABLE 4–1.—NUMBER OF RECREATIONAL USER ON LAKE SAKAKAWEA 

Recreation Site 2005 2006 2007 2008 

Fort Stevenson State Park ............................................ 948,435 1,208,383 975,556 952,910 

Lake Sakakawea State Park ......................................... 1,084,604 1,006,966 1,047,370 722,110 

Downstream .................................................................. 895,659 872,760 763,113 995,582 

Spillway Overlook .......................................................... 50,711 52,410 51,451 53,272 

Wolf Creek ..................................................................... 215,953 225,762 169,548 131,894 

East Totten Trail ........................................................... 774,454 789,407 811,685 696,755 

Douglas Creek ............................................................... 138,018 158,493 107,236 246,966 

Deep Water Creek ......................................................... 205,276 211,304 204,431 139,767 

Lewis and Clark State Park ......................................... 204,023 120,676 127,957 128,222 

Tobacco Garden ............................................................ 215,990 75,669 65,245 108,825 

McKenzie Bay ................................................................ 313,674 364,795 249,653 306,695 

Little Missouri 1 ............................................................. ........................ ........................ ........................ ........................

Charging Eagle ............................................................. 336,151 332,481 304,942 276,837 

Beulah Bay .................................................................... 512,623 540,316 391,570 450,855 

Missouri River Ramp .................................................... 297,261 310,459 310,276 328,106 

Riverdale Overlook ........................................................ 11,870 13,245 9,827 14,665 

Parshall Bay ................................................................. 579,234 618,510 416,201 465,110 

Van Hook Area .............................................................. 811,438 1,023,799 1,024,974 1,199,300 

New Town ...................................................................... 257,215 279,656 262,736 184,036 

Twin Buttes ................................................................... 28,117 16,857 32,401 16,678 

Hazen Bay ..................................................................... 229,406 249,017 302,255 277,534 

American Legion Park ................................................... 33,854 30,622 19,854 71,493 

Lake Trenton ................................................................. 263,887 207,277 230,401 253,550 

Little Beaver ................................................................. 8,246 12,195 9,714 14,540 

Power Plant ................................................................... 2,723 1,138 1,823 1,878 

Game Management ....................................................... 1,176,316 1,176,715 1,175,256 1,145,243 

Sportsmen’s Centennial (Benedict) .............................. 157,194 153,958 115,942 139,123 

White Earth Bay ............................................................ 75,431 96,543 107,446 75,389 

Beaver Creek ................................................................. 98,128 143,699 128,816 144,564 

Pouch Point Bay ........................................................... 229,132 147,288 103,956 172,127 

White Tail Bay .............................................................. 31,348 37,203 30,460 122,301 

Indian Hills ................................................................... 229,736 227,217 226,759 205,751 

West Totten Trail .......................................................... 14,771 18,170 14,441 15,397 

Lake Shore Park ............................................................ 562,616 548,735 582,109 576,504 

Government Bay ............................................................ 80,191 77,659 77,187 78,525 

Spillway Pond ............................................................... 24,239 15,702 16,171 22,855 

Little Muddy .................................................................. 34,001 27,320 18,883 26,619 

Little Egypt ................................................................... 11,517 13,303 11,777 10,229 

West Trail Race ............................................................ 37,594 38,728 34,070 41,480 

Reunion Bay .................................................................. 39,009 42,929 28,667 32,184 

Skunk Creek Bay ........................................................... 230,234 230,053 79,931 96,770 

Dispersed Use ............................................................... 1,706,500 1,706,092 1,913,077 2,268,823 

1 Drought conditions rendered the site unusable. 

(Source: USACE, 2008) 

Angling is the most popular recreation activity on Lake Sakakawea. Boating and 

sightseeing are also popular activities as they are often occurring within the same 

party on the same day. Table 4–2 summarizes the mix of activities and the primary 

purpose of trips taken by visitors to Lake Sakakawea. 

TABLE 4–2.—RECREATIONAL ACTIVITY MIX AT LAKE SAKAKAWEA 

Recreation Activity Percent of All Ac- tivities Percent of Visits 

Fishing ................................................................................................................................. 41 .7 23 .1 

Boating ................................................................................................................................ 39 .7 22 .0 
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4The total percent of activities is greater than 100 percent because many people participated 

in more than one activity at a given recreation area. 

TABLE 4–2.—RECREATIONAL ACTIVITY MIX AT LAKE SAKAKAWEA—Continued 

Recreation Activity Percent of All Activities Percent of Visits 

Sightseeing .......................................................................................................................... 31 .1 17 .2 

Other (jetskiing, hiking, playground, bird watching, pow-wows etc.) ............................... 22 .1 12 .2 

Camping .............................................................................................................................. 19 .5 10 .8 

Picnicking ............................................................................................................................ 11 .7 6 .5 

Swimming ........................................................................................................................... 8 .7 4 .8 

Hunting ................................................................................................................................ 3 .5 1 .9 

Waterskiing .......................................................................................................................... 2 .4 1 .3 

Winter Activities .................................................................................................................. < 1 < 1 

Total Percent2 ..................................................................................................................... 180 .5 100 

Activities Per Visit .............................................................................................................. 1 .8 ..........................

(Source: USACE 2007, modified by staff) 

4.2 Garrison Reach 

Visitor use estimates for the Garrison reach are more difficult to calculate. North 

Dakota Game and Fish Department (NDGFD) most recent creel surveys estimated 

95,322 angler days during 2007 (NDGFD 2007b) which amounted to over 338,000 

angler hours along this reach. Boat anglers accounted for over 80 percent of the estimate (NDGFD 2007b). Overall, visitation is likely much higher when considering 

the canoe trips and land based opportunities within the reach. 

4.3 Lake Oahe 

The USACE estimated recreational use of Lake Oahe sites within North Dakota 

totaled approximately 3.8 million visitor hours in 2008 (USACE 2008). Recreation 

sites that received the most visitor hours included: General Sibley Park with approximately 1.4 million visitor hours, Kimball Bottom with over 850,000 visitor 

hours, Beaver Creek with over 300,000 visitor hours, Graner Bottom with approximately 280,000 visitor hours, and Hazelton with nearly 272,000 visitor hours.4

Table 4093 shows the USACE visitor use estimates (actual users) for 15 formal and 

combined dispersed use areas around the lake for the years 2005 to 2008. 

TABLE 4–3.—NUMBER OF RECREATIONAL USERS ON LAKE OAHE 

Recreation Site 2005 2006 2007 2008 

Fort Yates ..................................................................... 122,523 96,178 53,727 60,646 

Cattail Bay .................................................................... 85,903 86,504 70,461 76,428 

Beaver Creek ................................................................. 276,485 234,492 277,777 329,614 

Badger Bay ................................................................... 5,538 4,587 3,416 4,670 

Hazelton ........................................................................ 104,741 150,906 173,419 271,992 

Fort Rice ....................................................................... 24,731 30,908 38,769 43,140 

Graner Bottom .............................................................. 235,735 150,473 265,718 280,006 

Little Heart (NDG&F Managed) ..................................... 148,686 163,741 168,123 115,290 

East Sibley Park (Nature Trail) .................................... 2,913 3,611 5,378 6,560 

General Sibley Park ...................................................... 702,388 995,321 1,343,763 1,439,609 

Kimball Bottom ............................................................. 838,378 656,671 620,293 856,412 

Langelier ....................................................................... 5,760 6,044 3,452 13,407 

Kimball Bottom ORV ..................................................... 257,240 214,088 1,999,598 137,449 

Maclean Bottom ............................................................ 134,692 187,071 208,501 146,657 

Prairie Knights Marina (Walker Bottom) ...................... 29,120 29,337 19,758 26,571 

Note.—This area of Oahe in North Dakota generally consisted of ‘‘river’’ conditions rather than ‘‘Lake’’ conditions during these years. 

(Source: USACE, 2008) 

Fishing, boating, and sightseeing are the most popular activities on Lake Oahe. 

According to the USACE, hunting accounts for 60 to 80 percent of total visitor hours 

in the fall, but may be misrepresented because of a lack of traffic counters on hunting related roads. Table 4–4 summarizes activity participation rates for visitors to 

Lake Oahe. 
122 

TABLE 4–4.—ACTIVITY MIX FOR LAKE OAHE 

Recreation Activity 

Activity Participation Rate 

(percent) 

Fishing .................................................................................................................................................................. 43.9 

Boating ................................................................................................................................................................. 30.0 

Sightseeing ........................................................................................................................................................... 22.0 

Other ..................................................................................................................................................................... 16.1 

Camping ............................................................................................................................................................... 7.0 

Swimming ............................................................................................................................................................. 5.6 

Hunting ................................................................................................................................................................. 4.9 

Picnicking ............................................................................................................................................................. 3.6 

Waterskiing ........................................................................................................................................................... 0.6 

Total 1 ...................................................................................................................................................... 133.7 

1 Totals more than 100 percent as users typically participate in more than one activity. 

(Source: USACE 2007, modified by staff) 

5.0 RECREATIONAL NEEDS 

USACE Lake Sakakawea Master Plan (2007) and Lake Oahe Draft Master Plan 

(2007) estimate that recreation use levels at both reservoirs are expected to grow 

in the coming years causing increasing demand for recreational facilities throughout 

the study area. Facility needs were identified by the North Dakota Parks and Recreation Department (NDPRD) in the North Dakota 2003–2008 State Comprehensive 

Outdoor Recreation Plan (SCORP) through the use of eight public forums (one for 

each SPR) that included recreation agency representatives and members of the general public. The top six recreational priorities of the planning districts adjacent to 

the study area were the same as those identified in the State and included: (1) 

Trails, (2) golf courses, (3) sports courts, (4) pools/beaches, (5) playgrounds/picnic 

areas, and (6) sports fields. Activities occurring in the study area but not in the top 

six were: water access (ranked 7th by adjacent planning districts), historic sites 

(ranked 8th by adjacent planning districts), and campgrounds (ranked 14th by adjacent planning districts). Because the study area offers the majority of flat water and 

a substantial amount of river based recreation opportunities in the State, the recreation sites within the study area will have to keep up with the demand for water 

access. 

6.0 EFFECTS OF SILTATION ON RECREATION RESOURCES 

Lake Sakakawea receives approximately 1,642 acre-feet of sediment as estimated 

at the Montana/North Dakota border (The Louis Berger Group [Berger], 2008). Sedimentation presents hazards to boaters, impairs fisheries, creates marshy areas, and 

jeopardizes recreation facilities (USACE, 2007). Siltation can negatively affect recreation resources in two ways: 

—Direct.—Affecting access or pathways within the reservoirs affecting visitors 

ability to access or utilize the water, compromising their safety, or affecting the 

aesthetic environment, or 

—Indirect.—Affecting physical properties within the reservoirs which in turn affect aspects of the recreationists overall trip (e.g., important fish habitat which 

would affect the recreational fishery). 

Loss of either access or declines in sport fish would have negative consequences 

on the amount of recreation visits to the study area which would have negative effects on the local economies that depend on recreation. Economic effects of sedimentation will be evaluated under a separate task for this project. 

Erosion and transport of silts and sediments into Lakes Sakakawea and Oahe can 

result in the aggradation near boat ramps posing problems to users and rendering 

them unusable. Dredging the ramps is currently performed when access is blocked 

by sediment build up on and around ramps; however this poses an ongoing maintenance cost to monitor and remove the sediments to keep ramps open. Complicating 

the management of sediment bound boat ramps are the lake levels. Severe drought 

in the recent past has resulted in very low lake levels which leaves some ramps out 

of the water or the ends of the ramps a long distance from the parking area. Sediment aggradation and boat ramp closures in areas with few points of access would 

cause additional strain as the cost to remove the sediment may outweigh the benefit 

of clearing the ramp resulting in ramp closures. Ramp closures in remote locations 

around the study area would force visitors to drive further to launch a boat. In some 
123 

areas, building a new ramp nearby is more cost effective than dredging existing 

ramps. 

In addition to compromising access to the water, siltation can compromise boater 

safety by filling in the historic river channel. When river channels are filled in the 

resulting shallower reservoir can cause unsuspecting boaters to hit bottom possibly 

injuring the boaters or causing damage to the boat motors. 

Sedimentation can also have negative effects on biological resources. Silt entering 

the study area settles to the bottom altering the bottoms of the river and reservoirs 

potentially negatively affecting spawning habitat. Walleye are the most sought after 

fish in the study area and the area has a productive walleye fishery. Walleye spawn 

on gravel and siltation greatly reduces the quantity and quality of walleye spawning 

habitat (Garrison Master Plan, 2007). 

Over time, sediment accumulations could fill in the deeper areas of the reservoirs 

potentially affecting fish habitat by altering water depth and ultimately the volume 

of cold water habitat necessary for some sport fish. The effects of such a situation 

would be exacerbated by drought conditions similar to the one experienced in recent 

years. Steps to preserve cold water habitat within Lake Sakakawea were undertaken by the Corps in 2005 and 2006 by (1) modifying the trash racks on 2 of the 

5 penstocks, (2) closing 2 of the 10 passage gates to restrict the opening to the dam’s 

power tunnels, and (3) altering the release schedule. The effects of sedimentation 

on the aquatic resources including the fisheries are discussed in greater detail under 

a separate task. 

Other effects of siltation occurring in areas other than boat ramps include modified stream channels and bathymetry which can have negative effects on water 

quality (shallow water equals warmer water which in turn could affect the fishery). 

Additionally, as sedimentation accumulates and point bars rise, and as water levels 

decline with the recent drought conditions, the area of land susceptible to overgrowth by invasive species increases, which can cause more problems (USACE 

2007). 

In reviewing existing USACE reports on sedimentation in the Missouri River, the 

areas of the river impacted most by the accumulation of sediments occur approximately 10 to 15 miles downstream from the upstream end of the lake zones (Lake 

Sakakawea and Lake Oahe) created by the Garrison and Oahe Dams. Most of the 

sediment accumulation is concentrated within a 30-mile reach of these points 

(Berger, 2008). A tremendous amount of sediment, including sediment from all upstream tributaries has accumulated in the headwaters of Lake Sakakawea (estimated annual deposit rate of 26,000 acre-feet annually) and has buried the old river 

channel downstream (NDGF 2002). Lower elevations in Lake Sakakawea do not provide additional riverine habitat but rather exposes vast expanses of accumulated 

sediments (NDGF 2002). 

Figure 6–1. shows the locations of formal recreation access sites with the sediment aggradation areas. According to the sediment aggradation maps, nearly all of 

the intensive use recreation sites on Lake Sakakawea are in areas of the lake with 

low to moderate sedimentation levels. On Lake Oahe, Graner Park Recreation Area 

and Kimball Bottom Recreation Area are areas of intense recreational use that are 

affected by high levels of sedimentation. MacLean Bottom Recreation Area is also 

identified as an area with high sedimentation levels but the site is considered a low 

density recreation area. In all, 1.1 million visitors recreated at sites within areas 

identified as either ‘‘low’’ or ‘‘moderate’’ areas of sediment aggradation on Lake 

Sakakawea and an additional 2.3 million visitors recreated at similarly identified 

sites in Lake Oahe according to the aggradation maps (Berger, 2008). 

The USACE provides high, mid, and low water ramps at many of the access areas 

to accommodate changes in reservoir levels which also provides alternative access 

during periods when ramps are covered with sediment. Most recently Fort Stevenson State Park, Government Bay, and Sanish Bay were locations within the reservoir impacted by sediment on the boat ramps affecting boater access. The Fort 

Stevenson West Ramp (low water ramp) was closed because it was entirely silted 

in, however a brand new marina ramp is being constructed on the northwest side 

of the park. Fort Stevens State Park is approximately 3 miles south of the town of 

Garrison; however it is not known if sediment is being loaded into the arm from 

tributary or in-reservoir sources. Government Bay and Sanish Bay were locations 

within the reservoir that required dredging to provide boater access. The Government Bay low water ramp was completely reconstructed within the last year because of siltation problems as the bay is filling up with silt and there is no longer 

a good location for moving the boat ramp. Complicating matters, the ramp cannot 

be extended because of a lack of room. In general, USACE’s recent solution has been 

to move or extend ramps rather than continue to dredge out areas, because it is less 

expensive (Linda Phelps, USACE personal communication). These areas are within 
124 

bays or smaller arms that are subject to local sedimentation processes and were not 

identified as areas of aggradation by the earlier Berger (2008) report that focused 

on changes in the elevations within the main channel and thalweg. 

FIGURE 6–1.—Developed Recreational Sites within Aggragation Areas 

Recent drought conditions have resulted in lower than normal lake levels in Lake 

Oahe changing the upstream character of the reservoir from a reservoir to that of 

riverine character. According to the USACE, channel shifting and erosion is occurring at Kimball Bottoms Recreation Area and MacLean Bottoms Recreation Area, 

limiting recreation access by undercutting the boat ramps or leaving them out of 

the water as the channel migrates away from the access area. Boat ramps and land 

based amenities need some level of protection and support from erosion processes. 

Rip rap has been installed over the years along the east side of Lake Oahe to protect the recreation sites from erosive processes; however this can be challenging in 

light of large fluctuations in reservoir elevations. 

7.0 SUMMARY AND RECOMMENDATIONS 

Erosion of the Missouri River above Lake Sakakawea and below Garrison dam 

poses the same problems in that sediment is moved in the channel and deposited 

in areas of calm water. When the reservoir is full, sediment is typically deposited 

further up the river but when the reservoir is down the channel is eroded and those 

sediments are moved within the channel downstream. 

Drought conditions and sedimentation/siltation processes can result in park or access closures preventing recreational access to areas within the reservoirs, directly 

impacting the recreation resources. The loss of boater access results in longer drives 

to launch boats, trip cancellation, poor aesthetics, and safety hazards to those using 

the Missouri River. Boat access site managers are forced to spend an increasing 

amount of time and resources to operate and maintain the boat ramps free of sediments to maintain boater access. Bays or arms just off the main channel have historically been the primary location of boater access; however these areas are susceptible to sediment aggradation as reported in interviews conducted for this research. 

It is important to note that these areas were not identified by the sediment 

aggradation modeling tool so the number of visitors affected by siltation is likely 

much higher. It is also important to remember that siltation can be a nuisance at 

boat ramps; however the reservoirs still provide greatest amount of flat water recreation opportunities in the state of North Dakota so that once on the water, 

recreationists may still report satisfactory trips. 

Successfully addressing sedimentation issues within the Missouri River will likely 

require a holistic approach and recommendations pertaining to the recreation resources would be a part of that solution. Lake Sakakawea and Lake Oahe are relatively young reservoirs and areas identified upon their creation as good or suitable 

recreation sites (e.g., within bays or off channel arms) have subsequently filled in 

with sediments. This process is likely to continue into the future until sediment 
125 

sources and in-reservoir sediment processes like shoreline erosion stabilize. Until 

then, identifying alternative boat ramp areas within existing parks may alleviate 

some maintenance of dredging ramps open and should be pursued when long term 

planning is initiated for the access sites. For example rebuilding boat ramps in 

areas less susceptible to sediment aggradation may have expensive up front costs; 

however the overall costs may be lower if there is no need for additional dredging 

of the ramps on a regular basis. As such, we recommend that strategic planning efforts identify and target areas that are currently susceptible to sediment 

aggradation, are close to population centers (e.g. Fort Stevens State Park) and have 

alternative ramp sites that would result in less sediment aggradation on the ramps. 

Permanent ramp closures is a viable option for access sites that do not have viable 

alternative locations for new ramps and have regular dredging needs. 

USACE maintains a Web site for the boat ramps on Lake Sakakawea and Lake 

Oahe that informs visitors of the reservoir depth and whether or not ramps are 

available for use. This is beneficial for visitors because it provides a method to check 

accessibility and plan trips in advance. We recommend that USACE continue to utilize the Web site planning tool. Although designed primarily for reservoir elevations, 

this trip planning tool possesses the ability to report closures due to sediment build 

up as well. Although not likely of interest to visitors, this could provide a way for 

the USACE to monitor sediment related closures. 

Boat ramps have been extended or relocated to accommodate for low water levels. 

Extension or relocation would also accommodate for sedimentation build up at boat 

ramps within the study area. Siltation of boat ramps and erosion in other areas 

along the Missouri River is occurring in certain areas posing a nuisance to some 

of the open water areas; however, overall there are tremendous opportunities in the 

area for flat water recreation and access to the reservoirs and rivers. Table 7–1 

summarizes the key findings related to the objectives of this task. 
126 

TABLE 7–1.—IMPACT OF SEDIMENTATION ON RECREATION RESOURCES 

Direct Impact Significance Timeline Recommendations 

Ramp or Access Closure ............ The lack of boater access results in longer drives to 

launch boats, trip cancellation, poor aesthetics, and safety hazards to those using the Missouri River. Boat access site managers are forced to spend an increasing amount of time and resources to operate and maintain the boat ramps free of sediments to maintain boater access.

Parks and access areas are predominantly used in the 

summer therefore summer time would have the greatest level of impact, however because sedimentation processes occur throughout the year, impacts to access areas would be on-going.

(1) Identify and prioritize areas, for long term planning 

purposes, that are currently susceptible to sediment aggradation and are close to population centers (e.g. Fort Stevens State Park) and identify alternative ramp sites that would result in less aggradation on the ramps. 

(2) Additional study of visitor’s willingness to travel in 

the event that popular boat ramps are closed and the proximity to nearby alternatives. 

(3) Evaluate extending or relocate boat ramps depending 

on the first parts above. 

(4) Evaluate closing ramps at sites that do not have 

viable alternative locations for new ramps and have regular dredging needs. 

Underwater hazards .................... Shallow water due to sediment deposition pose a risk to 

boaters and boating equipment.

Dynamic and dependent on reservoir elevations. Summer 

peak boating season with low lake levels pose the greatest risk.

Evaluate options of educating the boating public, signage and updating bathymetric mapping efforts. 
127 

Literature Cited 

The Louis Berger Group, Inc. Identification of Sources and Deposits and Locations 

of Erosion and Sedimentation. August 22, 2008. 

North Dakota Parks and Recreation Department. 2007. North Dakota State Comprehensive Outdoor Recreation Plan 2008–2012. North Dakota Parks and Recreation Department, Bismarck, ND. 2008. 

North Dakota Game and Fish Department. 2007a. Angler Use and Sport Fishing 

Catch Survey on Lake Sakakawea, North Dakota May 1 through September 30, 

2006. Written by: Larry Brooks, Jeff Hendrickson, and Dave Fryda. Project F–2–R– 

53, Bismarck, North Dakota. 

North Dakota Game and Fish Department. 2007b. Angler Use and Sport Fishing 

Catch Survey on the Missouri River and Lake Oahe, North Dakota April 1 through 

October 31, 2006. Larry Brooks, Jeff Hendrickson, and Dave Fryda. Project F–2–R– 

53, Bismarck, North Dakota. 

North Dakota Game and Fish Department. 2002. Official Department Position Papers; The Missouri and Yellowstone Rivers In North Dakota (Williston Reach)—A 

Report to the Director, 2002. 

North Dakota State Water Commission. 2005. A Reference Guide to Water in 

North Dakota. North Dakota State Water Commission, Governor John Hoeven, 

Chairman and Dale L. Frink, State Engineer. Bismarck, North Dakota. 

USACE (U.S. Army Corps of Engineers). 2008a Geographic Information System 

Recreation site information. Obtained via email communication between Eric Morrison, GIS specialist, Omaha District, USACE and Brian Lee, The Louis Berger 

Group, Inc. October 7, 2008. 

USACE (U.S. Army Corps of Engineers). 2008b Visitor Use Information. Obtained 

via email communication between Jerald L. Alexander, Natural Resource Specialist, 

Omaha District, USACE and Jot Splenda, The Louis Berger Group Inc., October 16, 

2008. 

USACE (U.S. Army Corps of Engineers). 2007. Garrison Dam/Lake Sakakawea 

Master Plan with Integrated Programmatic Environmental Assessment. U.S. Army 

Corps of Engineers—Omaha, District. Missouri River, North Dakota. 

USACE (U.S. Army Corps of Engineers). 2007. Preliminary Draft Oahe Dam/Lake 

Oahe Master Plan Missouri River, South Dakota and North Dakota. U.S. Army 

Corps of Engineers—Omaha, District. Riverdale, North Dakota. 

USACE (U.S. Army Corps of Engineers). 2005. Lake Sakakawea Garrison Dam 

Boat and Recreation Guide. U.S. Army Corps of Engineers—Omaha, District. Riverdale, North Dakota. 

USACE (U.S. Army Corps of Engineers). 2003. Operational Management Plan 

Garrison Project. Appendix F: Shoreline Management Plan. U.S. Army Corps of Engineers—Omaha, District. Riverdale, North Dakota. 

USACE (U.S. Army Corps of Engineers). 2003. Lake Oahe Dam Boat and Recreation Guide. U.S. Army Corps of Engineers—Omaha, District. Riverdale, North Dakota. 

USGS 2008. Missouri River Basin in North Dakota USGS Web site. Web site 

accessed at: http://nd.water.usgs.gov/missouririver/index.html. Web site accessed on 

November 14, 2008. Web site updated July 28, 2008. 

Other Information Sources: 

Minnesota Public Radio. Water Wars: Recreation on the Missouri River. Dan 

Gunderson. 2003. (http://news.minnesota.publicradio.org/features/2003/07/ 

03lgundersondlriverrecreation/). 

North Dakota Game and Fish Department. 2002–2007. Fisheries Management 

Plan Missouri River System. Jeff Hendrickson, Jason Lee, Dave Fryda, Greg Power, 

and Fred Ryckman. North Dakota Game and Fish Department, Bismarck, North 

Dakota. 

USACE (U.S. Army Corps of Engineers). 2008. Bank Stabilization Cumulative Impact Analysis Final Technical Report. U.S. Army Corps of Engineers, Omaha, Nebraska. 

USACE (U.S. Army Corps of Engineers). 2008. Quarterly Drought Report. U.S. 

Army Corps of Engineers—Omaha, District. Riverdale, North Dakota. 

USACE (U.S. Army Corps of Engineers). Revised 2006. Missouri River Mainstem 

Reservoir System Master Water Control Manual Missouri River Basin. U.S. Army 

Corps of Engineers, Reservoir Control Center Northwestern Division—Missouri 

River Basin. Omaha, Nebraska. 
128 

APPENDIX D—IMPACT OF SILTATION ON HYDROPOWER GENERATION, MISSOURI RIVER, 

NORTH DAKOTA

EXECUTIVE SUMMARY 

This report assesses the impacts of siltation in the Missouri River Basin within 

the State of North Dakota on hydropower facilities and operations. Hydropower facilities along the Missouri River in North Dakota consist of the Garrison Dam and 

its reservoir, Lake Sakakawea. In addition, hydropower operations in North Dakota 

are affected by the operation of Oahe Dam in South Dakota because Lake Oahe extends into southern North Dakota up to just south of the city of Bismarck when the 

pool is full. 

Hydropower Facilities 

The two reservoirs are part of the Missouri River Mainstem System (System) consisting of six dams in total. Construction of the System started in the 1930s with 

the Fort Peck Dam. Garrison Dam was closed in 1953; Oahe Dam was closed in 

1958. The Flood Control Act (Pick-Sloan Act) from 1944 specifies that the reservoirs 

were to be operated as an integrated system. Aside from hydropower, other uses are 

relevant in the operation of the System: flood control, navigation, irrigation, recreation, water supply, and fish and wildlife. 

The hydropower facilities of the System provide dependable energy to meet annual peak power demands of the region. Annual gross power production at the Garrison Dam was on average 2.29 million MWh from 1967 (2 years after Lake 

Sakakawea was filled) through 2007. However, hydropower operations at Garrison 

Dam have generally decreased over time to 1.31 MWh in 2007 due to drought. The 

main exception was a period in the mid-1990s with high precipitation in the upper 

Missouri River watershed. Peak months of outflow and thus energy generation are 

December, July, and August due to high power demand. 

Power release rates are commonly adjusted on a daily basis to support a variety 

of uses. The generated electricity is marketed by the Western Area Power Administration (WAPA) which is an agency of the Department of Energy (Western). Revenues are highest during the peak generation months in the winter and summer. The 

total revenues from energy generated at Garrison Dam in the last 5 years (2003 to 

2007) ranged from $15 million to $22 million. Highest annual revenues were generated during the wet year 1996 with $43 million. 

Impacts 

Potential impacts from siltation in the Missouri River on hydropower operations 

in North Dakota consist of the following: 

—Loss of Storage in Lake Sakakawea.—Lake Sakakawea traps nearly 100 percent 

of the sediment that enters the reservoir. Most of the sediment originates from 

the Missouri River and the Yellowstone River, a tributary to the Missouri River. 

This includes sediment that is eroded from the bank and bottom of the Missouri 

River, downstream of the Fort Peck dam. The USACE estimated a storage loss 

rate of 25,900 acre-feet/year (or 0.11 percent per year). At this rate, the life expectancy of Lake Sakakawea is approximately 900 years before it is completely 

filled. This value is a first-order estimate only, as the life expectancy depends 

on a number of variables such as sediment trapping efficiency (which decreases 

over time), climate variability over time, and sediment contributions from the 

watershed of Fort Peck Dam (sediment from its watershed is currently trapped 

in its reservoir). 

—Entrainment of Sediment Into the Turbines at Garrison Dam.—With an annual 

loss of storage capacity by 0.11 percent, and most of the deposition occurring 

in the upper reaches of the reservoir, impacts to the intakes to the hydropower 

facility are not expected for a long time. As a result, the USACE does not have 

any specific sediment management methods or sediment control facilities at 

their hydroelectric facilities at this time. 

—Reduced Releases at Garrison Dam in Winter Due to Flooding Risk From Sediment Aggradation.—Siltation in the reach between Garrison Dam and Lake 

Oahe has resulted in increased risk of flooding in the downstream reach between the dam and the headwater of Oahe Lake. The Missouri River typically 

freezes in December, remains frozen in January and February, and starts to 

thaw in March and April. A large consideration in flow releases are the potential formation of ice dams. Aggradation of the river channel in the headwaters 

of Lake Oahe has resulted in a slightly greater decrease in energy production 

in the colder months of the years than during the warmer months of the year. 
129 

Recommendations 

Releases from Garrison Dam by the USACE for various uses already aim to minimize flooding. Detailed monitoring data should continue to be collected to allow for 

effective adaptive management measures of the operations of Garrison Dam to 

maximize the benefit of the dam and the overall System, while minimizing impacts. 

This is particularly important in light of the fact that there are a number of natural 

variables that change regularly (daily, as well as longterm), such as rainfall, temperature, flow, erosion and deposition patterns, etc. In addition, the river serves 

multiple uses that also need to be balanced. 

Dredging could be considered on a temporary and localized basis for flood control, 

but a larger-scale dredging operation would most likely be cost-prohibitive. 

The risk of flooding will increase once the current drought has passed, and Lake 

Oahe again has full pool elevations. Higher pool elevations imply that sediment carried by the Missouri River will be settling out closer to the city of Bismarck than 

at present which will result in further aggradation. A higher risk of flooding requires further reduction in hydropower generation at Garrison Dam. The existing 

flood plain and zoning should be reviewed in the cities of Bismarck and Mandan 

(as well as in non-urban areas in the Garrison Dam to Lake Oahe reach) to determine if additional steps should be undertaken to better accommodate high flows in 

the Missouri River. Developments close to the river edge should be avoided, or potentially even reversed if feasible. Further, appropriate bank stabilization measures 

should be considered in areas most heavily affected by flooding. 

It is recommended to conduct a study that more quantitatively demonstrates that 

higher elevations in Lake Oahe will result in a decrease in flow velocities due to 

aggradation. This study would need to address the range of variables that affect the 

flow in order to extract the impact of lake elevations on outflow rates. 

1.0 INTRODUCTION 

The Louis Berger Group Inc. (Berger) was tasked by the U.S. Army Corps of Engineers (USACE) to assess impacts of sedimentation in the Missouri River Basin within the State of North Dakota. This assessment was intended to meet the level of 

effort defined in the Missouri River Protection and Improvement Act. The assessment had two objectives. First, Berger identified sources and deposit locations of 

sediment within the Missouri River Basin in the State of North Dakota, utilizing 

existing data and information. Next, the team analyzed the potential impacts of 

sedimentation on important issues and resources including: local, regional and national economies; recreation; hydropower generation; fish and wildlife; flood control 

and Indian and non-Indian historical and cultural sites. 

The study area was defined by the USACE to include the watershed of the 

mainstem of the Missouri River from the North Dakota-South Dakota border on the 

downstream end to the Montana-North Dakota border on the upstream end (Figure 

1–1). The study area was to include tributaries of the Missouri River, Lake 

Sakakawea and Lake Oahe. 

This report presents the results of Task 5D—Impact of Siltation on Hydropower 

Generation. The assessment was based on review of relevant existing data and information. Further, individuals familiar with specific aspects of this task were contacted. The following sections address the results of the task. Section 2 describes 

the hydropower facilities in the study area. Section 3 address siltation impacts on 

hydropower operations. Section 4 provides some recommendations. 
130 

FIGURE 1–1.—Location of the study area (Scale: 1 inch = 53 miles). 

2.0 HYDROPOWER FACILITIES 

2.1 Overview 

Hydropower facilities along the Missouri River in North Dakota consist of Garrison Dam and its reservoir, Lake Sakakawea (Figure 2–1). In addition, hydropower 

operations in North Dakota are affected by the operation of Oahe Dam in South Dakota. Lake Oahe extends into southern North Dakota, and can extend up to just 

south of the city of Bismarck when the pool is full. Oahe Dam is located just to the 

north of the city of Pierre in central South Dakota. 

Garrison Dam and Oahe Dam and their respective reservoirs are part of the Missouri River Mainstem System (System) consisting of six dams in total (Figure 2– 

2). The other four dams are Fort Peck Dam, Big Bend Dam, Fort Randall Dam, and 

Gavins Point Dam. The total drainage area at Gavins Point Dam is 279,480 square 

miles (Figure 2–3). 

Construction of the System started in the 1930s with the Fort Peck Dam. The 

other five dams were authorized in 1944 by the Flood Control Act (Pick-Sloan Act). 

This Act specified that the reservoirs were to be operated as an integrated system. 

Aside from hydropower, other uses are relevant in the operation of the System: flood 

control, navigation, irrigation, recreation, water supply, and fish and wildlife. In enacting this Act, Congress did not assign a priority to these operational purposes, as 

stated in the recent Record of Decision (ROD) for the Missouri River Master Control 

Manual Review and Update (USACE, 2004b). The ROD states further: 

‘‘Instead, it was contemplated that the Corps, in consultation with affected interests and other agencies, would consider all of the authorized purposes when making 

decisions to optimize development and utilization of the water resources of the Missouri River to best serve the needs of the people.’’ (p.1) 

The reservoirs in the System have defined zones to facilitate operations. These 

zones were developed for flood control, multiple uses, and the permanent pool (Figure 2–4). The six dams in the System are operated in an integrated manner to assure that the multi-use goals can be met. For example, Lake Sakakawea and Lake 

Oahe are significant for flood storage as they have the largest storage capacity of 

the six impoundments in the System (Figure 2–5). 

The reservoir zones are defined as follows (USACE, 2004a): 

—Exclusive Flood Control Zone.—This zone is the total upper volume of the 

mainstem lakes maintained exclusively for flood control. The System-wide capacity of this zone is 6 percent. Water is released from this zone as quickly as 

downstream channel conditions permit so that sufficient storage remains available for capturing future inflows. 
131 

—Annual Flood Control and Multiple Use Zone.—This zone is reserved for annual 

flood control and multiple uses. The System-wide capacity of this zone is 16 percent. This zone is used to store the high annual spring and summer inflows to 

the lakes in the System. Later in the year, water stored in this zone is released 

for riverine uses so that the zone is evacuated by the beginning of the next flood 

season on March 1. Evacuation is accomplished mainly during the summer and 

fall navigation season, because icing of the river may preclude high evacuation 

flows during the winter. 

FIGURE 2–1.—Aerial photograph of Garrison Dam (Source: Google Earth) 
132 

FIGURE 2–2.—Location of Garrison Dam and Oahe Dam, as part of the Missouri 

River Mainstem Reservoir System (USACE, 2004a). 
133 

Source: Missouri River Main Stem Reservoirs, Hydrologic Statistics, US Army 

Corps of Engineers, 1999 

FIGURE 2–3.—Total Drainage at Gavins Point Dam 

FIGURE 2–4.—Reservoir zone locations of the system (schematic) (USACE, 2004a). 
134 

FIGURE 2–5.—Missouri River mainstem system storage, by mainstem reservoir 

(USACE, 2004a). 

—Carryover Multiple Use Zone.—This zone is the largest portion of the System’s 

upper storage capacity, designed to provide water for all uses during drought 

periods. This zone is confined to Fort Peck Lake, Lake Sakakawea, Lake Oahe, 

and Lake Francis Case. The System-wide capacity of this zone is 53 percent. 

The zone is operated so that it remains full during periods of normal inflow but 

is gradually drawn down during drought periods. 

—Permanent Pool.—The remaining total storage capacity (25 percent Systemwide) is reserved as the permanent pool. Total capacity allocated for the permanent pool is approximately 18 million acre-feet System-wide. The permanent 

pool provides the minimal water level necessary to allow the hydropower plants 

to operate and to provide reserved space for sediment storage. It also serves as 

a minimum pool for recreation and for fish and wildlife habitat and as an ensured minimum level for pump diversion of water from the lakes. 
135 

2.2 Physical Characteristics 

2.2.1. Garrison Dam and Lake Sakakawea 

Garrison Dam is located at river mile (RM) 1390 in central North Dakota near 

the Town of Riverdale, approximately 75 river miles northwest of the city of Bismarck. The dam is 180 feet high and one of the largest rolled earthfill dams in the 

world. Its gross storage capacity is 23.8 million acre-feet (USACE, 2004a). Construction of the Garrison Project started in 1946. Closure of the dam and thus filling of 

Lake Sakakawea occurred in April 1953. Operation of the powerplant began in 

1955. The first three power-generating units were placed on line in 1956. Units 4 

and 5 were placed into operation in October 1960. 

Relevant physical characteristics of Garrison Dam, Lake Sakakawea, and the watershed for the lake are summarized below (USACE, 2000a; 2004a): 

—Garrison Dam 

—Date of Closure—April 1953 

—Height—180 feet 

—Width—11,300 feet 

—Lake Sakakawea 

—Pool Elevations (Figure 2–4): 

—Minimum Operating Pool (Top, Permanent Pool)—1,775.0 ft msl 

—Base Flood Control Level (Top, Carryover and Multiple Use Zone)—1,837.5 

ft msl 

—Maximum Normal Pool (Top, Annual Flood Control and Multiple Use 

Zone)—1,850.0 ft msl 

—Maximum Operating Pool (Top, Exclusive Flood Control Reserve)—1,854.0 

ft msl 

—Length of Reservoir (full)—178 valley miles 

—Maximum Depth (near dam)—180 feet 

—Shoreline Length (at 1,837.5 msl)—1,340 miles 

—Surface Area (at 1,837.5 msl)—380,000 acres 

—Surface Area (full)—593 sq.mi. 

—Gross Storage—23,821,000 acre-feet 

—Flood Storage—5,711,000 acre-feet 

—Carryover Storage—13,130,000 acre-feet 

—Mean Annual Outflow of Water 

—Rate—22,800 cfs 

—Volume—15.6 million acre-feet 

—Watershed 

—Drainage Area for Lake Sakakawea (at Garrison Dam): 

—Including the drainage area of Fort Peck Dam—181,400 sq. mi. 

—Excluding the drainage area of Fort Peck Dam—123,900 sq. mi. 

The Fort Peck Dam upstream of Lake Sakakawea was closed in 1937. Most of the 

sediment entering the Fort Peck Lake is captured by the reservoir, thus reducing 

the drainage area that supplies sediment to Lake Sakakawea by 32 percent. 

2.2.2. Oahe Dam and Lake Oahe 

Oahe Dam is located approximately 6 miles to the northwest of the city of Pierre, 

South Dakota, at RM 1072. It is 200 feet high and has a gross storage capacity is 

23.1 million acre-feet (Figure 2–5). Construction of the Oahe Project started in 1948. 

Closure of the dam was completed in 1958. The pool was first filled in 1962 and 

the first power unit came on line. All power units were operational in July 1966. 

Relevant physical characteristics of Lake Oahe are summarized below (USACE, 

2000a; 2004a): 

—Oahe Dam 

—Date of Closure—August 1958 

—Height—200 feet 

—Width—9,300 feet 

—Lake Oahe 

—Pool Elevations (Figure 2–4): 

—Minimum Operating Pool (Top, Permanent Pool)—1,540.0 ft msl 

—Base Flood Control Level (Top, Carryover and Multiple Use Zone)—1,607.5 

ft msl 

—Maximum Normal Pool (Top, Annual Flood Control and Multiple Use 

Zone)—1,617.0 ft msl 

—Maximum Operating Pool (Top, Exclusive Flood Control Reserve)—1,620.0 

ft msl 

—Length of Reservoir (full)—231 valley miles 

—Gross Storage—23,137,000 acre-feet 
136 

—Flood Storage—4,303,000 acre-feet 

—Carryover Storage—13,461,000 acre-feet 

—Watershed 

—Drainage Area for Lake Oahe (at Oahe Dam) 

—Including the drainage area of Garrison Dam—243,490 sq. mi. 

—Excluding the drainage area of Garrison Dam—62,090 sq. mi. 

2.3 Power Generation 

Most of the water stored in Lake Sakakawea is eventually moved through the reservoir system which enables power production (USACE, 2004a). Runoff between 

March and July supplies 70 percent of the water used for annual power generation. 

Water is only bypassed during larger magnitude inflow years. 

2.3.1. Garrison Dam and Lake Sakakawea 

The primary water management functions of Garrison Dam and Lake Sakakawea 

are as follows (USACE, 2006, Paragraph 7–02.3, p. VII–3): 

‘‘7.02–3.... (1) to capture the snowmelt runoff and localized rainfall runoffs 

from the large drainage area between Fort Peck and Garrison Dams that are then 

metered out at controlled release rates to meet System requirements, while reducing 

flood damage in the Garrison Dam and Lake Oahe reach, particularly the urban 

Bismarck area; 

‘‘(2) to serve as a secondary storage location for water accumulated in the System 

from reduced System releases due to major downstream flood control regulation, 

thus helping to alleviate large reservoir level increases in Oahe and Fort Randall; 

and 

‘‘(3) to provide the extra water needed to meet all of the System’s Congressionally 

authorized project purposes that draft storage during low water years.’’ 

There are general requirements for power generation as specified in the Garrison 

Standing Order from 1983 (Exhibit 1). This order specifies minimum releases for 

specific time periods. For example, over a 4 hour period, 300 MWh must be generated. The release pattern within these 4 hours to achieve at least 300 MWh can 

be chosen by WAPA. This requirement is designed to assure that municipal and industrial water intakes between Garrison Dam and Lake Oahe have sufficient water. 

There are a total of 123 intakes between Garrison Dam and Lake Oahe, which consist of 6 power plant intakes, 3 municipal water supply facilities, 6 industrial intakes, 77 irrigation intakes, 28 domestic intakes, and 3 public intakes (USACE, 

2006). Another requirement states that supplementary releases are only to be made 

as necessary to maintain a daily average release rate of 6,000 cfs at Garrison Dam. 

In addition to the Standing Order, the USACE provides WAPA with daily reservoir regulation and power production orders. These orders ensure that requirements for other uses as well as hydrological and meteorological conditions at the 

time are incorporated. For example, in summer, typically between May 15 and August 30, the shape of the releases is controlled due to nesting of endangered bird 

species below the Garrison Dam. This limits the peaking pattern for power generation. Also, in winter, release rates are determined based on requirements for icein and flood control conditions. 

Releases at Garrison Dam in the winter that are affected by flood control considerations are defined in the Master Water Control Manual (USACE, 2006, p. VII– 

17) as follows: 

‘‘7–04.7.1. Fort Peck and Garrison Flood Control Considerations. The winter season is the time period when the firm power demand from the System is the 

greatest. To enhance winter energy generation, winter releases from the upstream 

Fort Peck and Garrison reservoirs are often maintained at the maximum level possible that is consistent with downstream channel capacity. During the winter, channel capacity is reduced because of threat of flooding during river ice formation or 

when an established Missouri River ice cover raises Missouri River stages. Because 

of the somewhat unpredictable behavior of a downstream ice cover, the exact potential volume of winter releases from these upstream projects cannot be estimated accurately. Prewinter System reservoir storage levels are scheduled on the basis that the 

established winter release rate will be made most of the time through these upstream 

powerplants. If channel conditions during the winter are such that the established 

winter release rate assumed in prewinter scheduling is not possible, a release deviation will be implemented. The changed release rate may result in some imbalance 

in the amount of water-in-storage in individual System reservoirs by the following 

spring. This storage imbalance will favor the downstream flood control purpose, with 

additional evacuated storage space located in the largest downstream System project, 

Oahe. This is not a matter of great concern because open-water channel capacities 
137 

below Fort Peck and Garrison are sufficient to allow a relatively fast restoration of 

System storage balance following the ice breakup if attaining a balance in the 

amount of water-in-storage at the large upper three reservoirs is still a goal at that 

time of the season.’’ 

Additional considerations during the winter ice season, as they affect flow releases 

and thus hydropower generation, consist of the following (USACE, 2006, p. VII–19): 

‘‘7–04.9. System Regulation Considerations During Winter Ice Season. The 

maximum flow that may be passed without damage varies through the length of the 

Missouri River and is dependent on channel dimensions, the degree of encroachment 

onto the floodplain, and improvements such as levees and channel modifications. Capacities at specific locations also vary from season to season, especially in the middle 

and upper river reaches, where a decrease in capacity due to the formation of an ice 

cover is common through the winter and early spring months. Like with most 

streams, the capacity of the Missouri River channel usually increases progressively 

downstream, although instances occur where this trend is reversed.’’ 

7–04.9.4. Ice cover forming on the Missouri River below Fort Peck, Garrison, and 

Oahe Dams has a marked effect on the winter regulation of these projects. At the time 

the ice cover first forms below Fort Peck and Garrison Dams, the downstream channel capacities are at a minimum. As the river ice cover stabilizes, flows are normally 

slowly increased followed by a progressive increase in the channel capacity that continues until just prior to the end of the winter season. It is often possible to increase 

releases while maintaining relatively constant downstream stages. This phenomenon 

is discussed in more detail in two RCC Technical Reports, ‘‘Freezing of the Missouri 

River Below Garrison Dam,’’ February 1973, and ‘‘Freezing of the Missouri River 

Below Fort Peck Dam,’’ July 1973. (p. VII–20 to 21) 

Lake Sakakawea reached its minimum operating level (1,775 feet msl) in late 

1955. The Carryover Zone and Multiple Use Zone was reached only 10 years later, 

in 1965, due to drought conditions (Figure 2–6). The lake remained generally filled 

from that time through 1976. Exclusive Flood Control storage space (1,854 feet msl) 

was used in 1969, 1975, 1995, and 1997. During 1975, all flood control space was 

filled and the maximum reservoir level was 0.8 feet above the base of the surcharge 

pool. Since then the reservoir elevation has dropped to below the Carryover Zone 

and Multiple Use Zone, specifically in the periods between 1987 and 1993, and from 

2000 to the present (Figure 2–7; Table 2–1). 

The minimum and maximum monthly elevations on Lake Sakakawea have a 

range of approximately 5 to 15 feet on an annual basis (Figure 2–8). During the 

winter months (December to February), elevations vary only by a few feet due to 

the ice cover (Figure 2–9). 

The power generation facilities are owned and operated by the U.S. Government. 

The Western Area Power Administration (WAPA; discussed in more detail in Section 2.4 below) markets and transmits the energy produced by the facility and thus 

requests releases from the operators within USACE specified requirements. 
138 

FIGURE 2–6.—End-of month pool elevations in Lake Sakakawea between closure of 

Garrison Dam in 1953 and 1993 (Source: USACE, 1993a). 

FIGURE 2–7.—End-of month pool elevations in Lake Sakakawea between 1967 (2 

years after reservoir was filled) and the present (Source of data: USACE). 
139 

TABLE 2–1.—END-OF-MONTH ELEVATION OF LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN FEET msl) 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN 

1967 ................................................. .............. .............. .............. .............. .............. 1,845.0 1,849.5 1,846.2 1,844.9 1,842.9 1,841.5 1,839.2 .............. .............. .............. 1,835.8 1,839.2 1,837.6 1968 ................................................. 1,837.3 1,835.8 1,838.4 1,837.2 1,836.7 1,843.8 1,846.7 1,847.2 1,847.1 1,845.2 1,844.5 1,842.6 1,835.8 1,847.2 1,841.9 1,838.1 1,842.6 1,840.6 1969 ................................................. 1,840.3 1,838.1 1,839.3 1,842.6 1,844.7 1,848.0 1,850.5 1,848.5 1,846.6 1,844.9 1,843.4 1,840.7 1,838.1 1,850.5 1,844.0 1,837.3 1,840.7 1,838.2 1970 ................................................. 1,838.4 1,837.5 1,837.3 1,837.3 1,839.9 1,846.1 1,848.8 1,847.1 1,846.8 1,845.6 1,844.0 1,842.0 1,837.3 1,848.8 1,842.6 1,839.9 1,843.6 1,841.8 1971 ................................................. 1,839.9 1,840.4 1,843.3 1,843.6 1,843.0 1,848.3 1,848.8 1,847.1 1,846.5 1,846.6 1,845.4 1,843.4 1,839.9 1,848.8 1,844.7 1,840.2 1,847.7 1,843.8 1972 ................................................. 1,841.3 1,840.2 1,847.7 1,846.5 1,845.8 1,848.8 1,848.9 1,848.7 1,847.9 1,847.3 1,846.7 1,845.3 1,840.2 1,848.9 1,846.3 1,842.8 1,845.3 1,843.7 1973 ................................................. 1,843.6 1,842.8 1,843.4 1,843.2 1,845.5 1,848.9 1,848.7 1,847.2 1,846.8 1,845.6 1,843.8 1,842.3 1,842.3 1,848.9 1,845.2 1,838.6 1,842.3 1,840.0 1974 ................................................. 1,840.4 1,839.0 1,838.6 1,839.8 1,840.5 1,846.6 1,849.0 1,847.9 1,847.1 1,845.1 1,844.0 1,842.3 1,838.6 1,849.0 1,843.4 1,838.7 1,842.7 1,840.7 1975 ................................................. 1,841.0 1,839.0 1,838.7 1,842.7 1,846.2 1,851.3 1,854.8 1,851.2 1,848.2 1,846.2 1,844.0 1,842.0 1,838.7 1,854.8 1,845.4 1,840.4 1,842.5 1,841.6 1976 ................................................. 1,840.9 1,840.4 1,842.5 1,842.4 1,843.2 1,847.8 1,848.0 1,846.2 1,845.1 1,843.5 1,841.7 1,840.0 1,840.0 1,848.0 1,843.5 1,835.8 1,840.0 1,837.1 1977 ................................................. 1,837.3 1,836.2 1,836.1 1,835.8 1,836.0 1,837.7 1,836.9 1,835.6 1,835.2 1,834.8 1,833.0 1,831.0 1,831.0 1,837.7 1,835.5 1,825.7 1,836.0 1,830.5 1978 ................................................. 1,828.0 1,825.7 1,831.7 1,836.0 1,842.5 1,847.5 1,849.3 1,847.0 1,845.7 1,843.8 1,840.9 1,839.8 1,825.7 1,849.3 1,839.8 1,834.9 1,843.9 1,838.5 1979 ................................................. 1,836.8 1,834.9 1,837.0 1,843.9 1,844.8 1,845.3 1,846.0 1,845.6 1,844.6 1,844.3 1,843.1 1,842.2 1,834.9 1,846.0 1,842.4 1,837.1 1,842.2 1,839.1 1980 ................................................. 1,840.5 1,838.5 1,837.3 1,837.1 1,837.6 1,839.7 1,839.4 1,838.4 1,837.9 1,837.1 1,835.6 1,833.6 1,833.6 1,840.5 1,837.7 1,828.5 1,833.6 1,830.9 1981 ................................................. 1,832.3 1,830.5 1,829.6 1,828.5 1,829.8 1,835.5 1,835.3 1,834.1 1,833.3 1,833.3 1,834.0 1,832.9 1,828.5 1,835.5 1,832.4 1,829.0 1,834.3 1,831.4 1982 ................................................. 1,830.6 1,829.0 1,830.1 1,834.3 1,834.8 1,840.5 1,845.0 1,845.3 1,845.0 1,845.5 1,843.0 1,842.0 1,829.0 1,845.5 1,838.8 1,839.5 1,842.0 1,841.0 1983 ................................................. 1,841.7 1,841.2 1,840.7 1,839.5 1,839.9 1,843.3 1,846.6 1,845.0 1,843.1 1,843.4 1,843.2 1,841.4 1,839.5 1,846.6 1,842.4 1,839.1 1,841.4 1,839.9 1984 ................................................. 1,840.0 1,839.1 1,839.5 1,839.5 1,842.4 1,847.7 1,849.2 1,847.2 1,845.2 1,844.6 1,843.2 1,841.6 1,839.1 1,849.2 1,843.3 1,838.1 1,841.6 1,839.6 1985 ................................................. 1,840.0 1,838.1 1,838.9 1,839.3 1,840.1 1,841.2 1,840.1 1,839.6 1,838.4 1,838.6 1,837.1 1,835.7 1,835.7 1,841.2 1,838.9 1,833.0 1,836.6 1,835.2 1986 ................................................. 1,834.3 1,833.0 1,836.6 1,836.6 1,840.5 1,846.5 1,848.4 1,846.3 1,846.3 1,846.4 1,844.7 1,843.5 1,833.0 1,848.4 1,841.9 1,840.1 1,843.5 1,841.7 1987 ................................................. 1,841.5 1,840.1 1,841.0 1,842.2 1,843.2 1,843.1 1,842.7 1,841.6 1,840.5 1,839.7 1,839.1 1,837.3 1,837.3 1,843.2 1,841.0 1,831.0 1,837.3 1,833.8 1988 ................................................. 1,835.2 1,833.0 1,832.7 1,831.0 1,831.2 1,832.2 1,830.2 1,827.4 1,825.9 1,825.0 1,824.7 1,823.2 1,823.2 1,835.2 1,829.3 1,820.1 1,823.6 1,822.1 1989 ................................................. 1,821.8 1,820.1 1,822.0 1,823.6 1,824.8 1,826.7 1,825.9 1,823.4 1,823.0 1,823.8 1,823.2 1,821.1 1,820.1 1,826.7 1,823.3 1,819.2 1,821.1 1,819.9 1990 ................................................. 1,819.8 1,819.2 1,820.3 1,819.2 1,819.4 1,821.9 1,822.9 1,821.1 1,821.0 1,821.6 1,821.9 1,819.7 1,819.2 1,822.9 1,820.7 1,815.6 1,819.7 1,817.0 1991 ................................................. 1,817.6 1,815.7 1,816.6 1,815.6 1,817.8 1,826.4 1,828.7 1,826.5 1,826.5 1,827.3 1,826.7 1,824.8 1,815.6 1,828.7 1,822.5 1,820.8 1,824.8 1,822.2 1992 ................................................. 1,822.4 1,820.8 1,821.8 1,821.3 1,821.4 1,823.4 1,824.9 1,823.0 1,821.8 1,821.3 1,821.3 1,818.8 1,818.8 1,824.9 1,821.9 1,816.8 1,820.5 1,818.5 1993 ................................................. 1,816.9 1,816.8 1,819.4 1,820.5 1,822.9 1,828.8 1,835.6 1,837.1 1,837.2 1,837.2 1,837.1 1,837.0 1,816.8 1,837.2 1,828.9 1,836.2 1,842.0 1,838.6 1994 ................................................. 1,836.5 1,836.2 1,841.3 1,842.0 1,843.8 1,845.0 1,843.5 1,841.3 1,839.8 1,840.3 1,838.7 1,837.8 1,836.2 1,845.0 1,840.5 1,835.5 1,837.8 1,836.5 1995 ................................................. 1,836.0 1,835.5 1,836.5 1,836.5 1,839.9 1,846.5 1,851.6 1,849.2 1,845.6 1,842.8 1,840.4 1,838.9 1,835.5 1,851.6 1,841.6 1,837.8 1,842.9 1,840.2 1996 ................................................. 1,837.8 1,839.5 1,841.8 1,842.9 1,842.9 1,848.2 1,849.0 1,845.8 1,842.3 1,840.8 1,839.9 1,838.9 1,837.8 1,849.0 1,842.5 1,838.0 1,847.5 1,841.6 1997 ................................................. 1,838.0 1,839.4 1,844.4 1,847.5 1,847.8 1,853.7 1,852.2 1,849.9 1,846.9 1,843.4 1,841.4 1,840.7 1,838.0 1,853.7 1,845.4 1,839.3 1,840.7 1,839.6 1998 ................................................. 1,839.3 1,839.3 1,839.4 1,839.3 1,839.2 1,840.8 1,843.0 1,842.6 1,841.6 1,842.3 1,841.8 1,840.4 1,839.2 1,843.0 1,840.8 1,838.9 1,841.7 1,840.3 1999 ................................................. 1,839.5 1,838.9 1,841.7 1,840.8 1,842.0 1,846.3 1,847.1 1,845.5 1,844.1 1,844.0 1,842.0 1,840.6 1,838.9 1,847.1 1,842.7 1,836.0 1,840.6 1,838.2 
140 

TABLE 2–1.—END-OF-MONTH ELEVATION OF LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN FEET msl)—Continued 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN 

2000 ................................................. 1,839.3 1,837.7 1,837.3 1,836.0 1,835.6 1,838.0 1,837.4 1,834.6 1,833.1 1,832.7 1,830.5 1,829.0 1,829.0 1,839.3 1,835.1 1,828.3 1,830.9 1,829.5 2001 ................................................. 1,828.7 1,828.3 1,830.4 1,830.9 1,831.6 1,833.8 1,834.4 1,832.8 1,831.8 1,831.1 1,830.5 1,829.2 1,828.3 1,834.4 1,831.1 1,826.9 1,829.2 1,827.9 2002 ................................................. 1,828.3 1,827.6 1,826.9 1,827.5 1,828.3 1,831.4 1,831.4 1,829.2 1,827.5 1,826.6 1,824.6 1,822.5 1,822.5 1,831.4 1,827.7 1,819.7 1,822.5 1,821.5 2003 ................................................. 1,821.1 1,819.7 1,822.4 1,821.7 1,822.6 1,827.0 1,826.1 1,822.9 1,820.9 1,820.1 1,819.1 1,818.4 1,818.4 1,827.0 1,821.8 1,814.3 1,818.4 1,815.9 2004 ................................................. 1,816.7 1,814.3 1,815.6 1,814.7 1,815.3 1,816.5 1,816.5 1,814.3 1,813.3 1,813.1 1,812.3 1,810.0 1,810.0 1,816.7 1,814.4 1,806.6 1,810.0 1,808.4 2005 ................................................. 1,808.4 1,808.2 1,808.7 1,806.6 1,808.8 1,814.9 1,817.2 1,815.8 1,814.1 1,814.0 1,813.5 1,812.0 1,806.6 1,817.2 1,811.9 1,810.6 1,812.5 1,811.4 2006 ................................................. 1,811.4 1,810.6 1,810.7 1,812.5 1,814.7 1,817.4 1,815.5 1,812.1 1,809.5 1,809.6 1,808.9 1,807.8 1,807.8 1,817.4 1,811.7 1,806.9 1,808.7 1,807.8 2007 ................................................. 1,807.0 1,806.9 1,808.7 1,808.6 1,813.1 1,818.1 1,816.9 1,814.6 1,813.7 1,813.2 1,812.7 1,810.9 1,806.9 1,818.1 1,812.0 1,807.3 1,810.9 1,808.5 2008 ................................................. 1,809.1 1,807.6 1,807.6 1,807.3 1,810.2 1,819.6 1,825.6 1,825.5 1,825.6 .............. .............. .............. .............. .............. .............. .............. .............. ..............

STATISTICS (JANUARY 1968 TO DECEMBER 2007) 

NUM .................................................. 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 MIN ................................................... 1,807.0 1,806.9 1,808.7 1,806.6 1,808.8 1,814.9 1,815.5 1,812.1 1,809.5 1,809.6 1,808.9 1,807.8 1,806.6 1,816.7 1,811.7 1,806.6 1,808.7 1,807.8 MEAN ................................................ 1,832.2 1,831.2 1,832.7 1,833.2 1,834.5 1,838.4 1,839.3 1,837.6 1,836.4 1,835.8 1,834.6 1,833.1 1,829.7 1,839.9 1,834.9 1,830.1 1,834.1 1,831.9 MAX .................................................. 1,843.6 1,842.8 1,847.7 1,847.5 1,847.8 1,853.7 1,854.8 1,851.2 1,848.2 1,847.3 1,846.7 1,845.3 1,842.3 1,854.8 1,846.3 1,842.8 1,847.7 1,843.8 STDEV ............................................... 10.3 10.4 10.6 11.0 10.8 10.9 11.4 11.7 11.6 11.2 10.9 11.0 10.6 11.2 10.7 10.9 11.4 11.1 

1 Rows include Jan to Apr of following year. 
141 

FIGURE 2–8.—End-of-month pool elevations in Lake Sakakawea; monthly mean, 

minimum and maximum for each year (Source of data: USACE). 

Figure 2–9.—End-of-month pool elevations in Lake Sakakawea; monthly mean, minimum and maximum in winter only (Dec–Feb) for each year (Source of data: 

USACE). 

Outflows from Lake Sakakawea at Garrison Dam are commonly through the 

power facilities. The power facilities have a normal capacity of 38,000 cfs and a 

maximum capacity of 41,000 cfs (USACE, 2008). The average outflow is 22,800 cfs, 

resulting in an annual plant factor of approximately 60 percent (USACE, 2006). In 

1975 and 1997, record high runoff in the upper Missouri River watershed required 

outflows of 65,000 cfs and 59,000 cfs, respectively, which partially bypassed the 

power facilities. The minimum mean daily release rate since 1956 occurred in 1997 

at 4,100 cfs (USACE, 2006). 

Flows in spring and fall may be reduced to between 10,000 and 15,000 cfs during 

droughts to conserve water; this rate provides the minimum protection of water supply intakes, water quality, irrigation needs, recreation, and fish and wildlife 

(USACE, 2004a). Flows may be 20,000 to 30,000 cfs during flood evacuation periods. 

Flows are also sensitive to bird nesting (USACE, 2004a, p. 3–12): 
142 

1 Net energy generation is consistently about 99.5 percent of gross energy generation. The difference between gross and net is that gross includes generator loss through the transformers 

and the amount of power the plant uses (station service) to generate the power (James Mueller, 

USACE, personal communication, January 8, 2009). 

‘‘To discourage terns and plovers from nesting too near the water during the midMay through August nesting period, daily releases are usually fixed at a constant 

rate in the 19,000 to 26,000 cfs range with hourly peaking limited to 6 hours a day 

near 30,000 cfs. This release pattern restricts hydropower capacity to less than full 

powerplant capacity. During prolonged droughts, daily average releases for the birds 

may be in the 10,000 to 15,000 cfs range with peaking restricted even further. During large system inflow years, large flood control evacuation release rates are necessary and nesting flow restrictions are lifted.’’ 

Garrison Dam has a five unit power plant. The combined generating capacity of 

the five turbines at Garrison Dam is 583.3 MW (Jody Farhat, pers. communication, 

November 14, 2008). This reflects a recent upgrade from previously 518 MW 

(USACE, 2006). 

Annual gross power generation at Garrison Dam was on average 2.29 million 

MWh from 1967 (2 years after Lake Sakakawea was filled) through 2007 (Table 2– 

2).1 During this time, the annual power generation at the dam has ranged from 1.31 

million MWh in 2007 to 3.35 million MWh in 1975 (Figures 2–10 and 2–11). In general, power generation has decreased over time, largely as a function of decreased 

runoff in the watershed caused by drought. The exception occurred during the mid1990s when spring snowmelting and high rainfall in the Upper Missouri River watershed resulted in high power generation rates. 

On a monthly basis, the range between minimum and maximum monthly power 

generation is generally greater with higher total annual generation (Figure 2–12). 

The lowest monthly generation during any year since 1967 was 82,820 MWh (November 2007). The highest monthly generation during any year since 1967 occurred 

in July 1997 with 377,870 MWh. 

Hydropower generation is highest during the winter heating season (December to 

mid-February) and in the summer when air-conditioning systems are used (midJune to early September) (Figure 2–13). Almost all of the power generated at Garrison Dam is supplied to the grid; less than 1 percent of the total power produced 

is used for on-site operations (Jody Farhat, personal communications, November 14, 

2008). 

2.3.2. Oahe Dam and Lake Oahe 

The primary water management functions of Oahe Dam and Lake Oahe are similar to the functions of Garrison Dam and Lake Sakakawea, as defined in the Master 

Water Control manual as follows (USACE, 2006, p. VII–3): 

‘‘(1) To capture plains snowmelt and localized rainfall runoffs from the large 

drainage area between Garrison and Oahe Dams that are then metered out at controlled release rates to meet System requirements, while reducing flood damages in 

the Oahe Dam to Big Bend reach, especially in the urban Pierre and Fort Pierre 

areas; 

‘‘(2) To serve as a primary storage location for water accumulated in the System 

from reduced System releases due to major downstream flood control regulation, 

thus helping to alleviate large reservoir level increases in Big Bend, Fort Randall, 

and Gavins Point; and 

‘‘(3) To provide the extra water needed to meet project purposes that draft storage 

during low-water years, particularly downstream water supply and navigation. 

‘‘In addition, hourly and daily releases from Big Bend and Oahe Dams fluctuate 

widely to meet varying power loads. Over the long term, their release rates are 

geared to back up navigation releases from Fort Randall and Gavins Point Dams 

in addition to providing storage space to permit a smooth transition in the scheduled annual fall drawdown of Fort Randall. Big Bend, with less than 2 million acrefeet of storage, is primarily used for hydropower production, so releases from Oahe 

are generally passed directly through Big Bend.’’ 

The Carryover and Multiple Use space (1,607.5 ft msl) of Lake Oahe was filled 

in 1967. This space remained generally filled with the exception of the periods between 1987 and 1993, and from 2000 to the present (Table 2–3; Figures 2–14 and 

2–15). Monthly variability was lowest during winter months (Figure 2–16). The variability in the elevations in Lake Oahe was very similar to the variability in Lake 

Sakakawea (Figures 2–7 to 2–9), as expected given the primary water management 

functions of Lake Oahe (stated above). Outflows are typically through the power facilities. 
143 

The highest monthly elevations occurred in June 1995, June 1996, and July 1997 

with elevations of 1,618 feet msl. In 2007, the maximum monthly lake elevation was 

35 feet lower at 1,583 feet msl (June 2007). 
144 

TABLE 2–2.—GROSS ENERGY PRODUCTION IN GARRISON RESERVOIR, JUNE 1967 TO SEPTEMBER 2008 (IN MWh) 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr)

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX TOTAL MEAN MIN MAX MEAN 

1967 ............................. .............. .............. .............. .............. .............. 232,818 295,092 336,767 237,050 275,633 237,942 241,156 232,818 336,767 .................. .............. 172,681 252,539 222,647 1968 ............................. 252,539 250,001 172,681 196,858 181,466 149,118 156,431 189,139 212,389 290,561 220,158 234,317 149,118 290,561 2,505,658 208,805 226,709 274,214 255,821 1969 ............................. 270,694 273,173 274,214 226,709 220,131 163,022 257,475 282,114 238,412 234,153 234,215 270,807 163,022 282,114 2,945,119 245,427 184,253 270,807 227,939 1970 ............................. 238,768 229,732 184,253 216,135 249,277 249,694 253,971 260,164 202,972 254,324 255,847 226,249 184,253 260,164 2,821,386 235,116 226,249 310,917 263,027 1971 ............................. 278,471 237,686 261,810 310,917 344,378 316,965 332,812 252,987 219,089 227,357 231,432 227,571 219,089 344,378 3,241,475 270,123 227,571 339,180 265,772 1972 ............................. 264,805 246,236 251,070 339,180 355,277 337,281 259,622 223,343 193,055 207,270 207,332 216,580 193,055 355,277 3,101,051 258,421 184,710 252,601 220,806 1973 ............................. 252,601 214,626 235,511 184,710 162,558 175,566 195,675 200,477 182,992 184,094 183,062 216,226 162,558 252,601 2,388,098 199,008 173,132 239,337 215,725 1974 ............................. 239,337 220,615 229,313 173,132 193,606 216,058 250,441 265,274 217,902 274,602 224,294 229,846 173,132 274,602 2,734,420 227,868 159,040 229,846 209,749 1975 ............................. 202,670 228,625 228,566 159,040 300,368 344,928 327,106 346,401 344,051 307,207 301,414 259,895 159,040 346,401 3,350,271 279,189 238,366 280,298 257,492 1976 ............................. 238,366 267,342 241,560 280,298 293,607 337,657 347,855 297,624 241,298 240,857 267,802 222,627 222,627 347,855 3,276,893 273,074 145,158 261,495 208,742 1977 ............................. 261,495 226,827 187,604 145,158 146,577 140,361 161,710 149,503 130,351 116,836 144,514 188,750 116,836 261,495 1,999,686 166,641 152,426 238,901 194,929 1978 ............................. 238,901 223,758 170,809 152,426 147,911 282,902 365,976 359,461 297,607 294,386 288,538 216,800 147,911 365,976 3,039,475 253,290 216,800 273,286 244,758 1979 ............................. 273,286 242,247 243,472 247,986 337,281 326,261 248,273 200,522 161,316 143,923 131,469 185,069 131,469 337,281 2,741,105 228,425 180,241 250,217 214,344 1980 ............................. 211,978 250,217 244,215 180,241 171,693 187,355 242,163 220,382 195,389 205,592 215,010 192,581 171,693 250,217 2,516,816 209,735 144,434 223,298 196,664 1981 ............................. 223,298 221,708 201,301 144,434 157,530 220,945 258,497 211,709 169,211 137,018 134,494 174,483 134,494 258,497 2,254,628 187,886 150,534 246,046 206,238 1982 ............................. 229,612 246,046 230,513 150,534 220,269 205,686 241,775 196,792 165,964 182,936 273,082 214,505 150,534 273,082 2,557,714 213,143 195,282 265,769 226,011 1983 ............................. 195,282 252,410 265,769 202091 158451 166,381 171,991 255,878 213,868 133,385 156,472 209,450 133,385 265,769 2,381,428 198,452 149,491 255,688 205,239 1984 ............................. 255,688 234,352 177,212 149,491 133,458 133,898 219,728 268,821 241,132 229,359 235,378 208,485 133,458 268,821 2,487,002 207,250 160,436 252,369 207,842 1985 ............................. 252,369 240,712 177,209 160,436 177,001 188,864 185,625 173,756 156,144 127,688 139,786 199,184 127,688 252,369 2,178,774 181,565 170,761 235,321 209,425 1986 ............................. 235,321 212,537 229,322 170,761 99,653 141,125 188,609 235,182 184,242 214,922 226,168 193,816 99,653 235,321 2,331,658 194,305 97,604 231,899 181,663 1987 ............................. 226,673 231,899 158,323 97,604 148,884 169,561 180,083 178,711 154,063 127,735 122,734 191,642 97,604 231,899 1,987,912 165,659 159,051 223,301 189,689 1988 ............................. 198,547 223,301 175,902 159,051 168,085 166,187 172,799 160,599 117,128 95,739 94,058 159,654 94,058 223,301 1,891,050 157,588 130,908 170,372 152,551 1989 ............................. 163,976 170,372 137,847 130,908 182,384 192,195 198,356 190,547 108,517 95,189 158,685 170,366 95,189 198,356 1,899,342 158,279 128,636 206,707 160,120 1990 ............................. 206,707 148,555 128,636 146,336 164,180 168,175 172,163 158,428 92,532 88,832 96,474 148,656 88,832 206,707 1,719,674 143,306 103,663 173,156 145,017 1991 ............................. 173,156 159,305 103,663 140,304 163,980 161,695 174,731 173,966 118,687 116,791 122,517 166,840 103,663 174,731 1,775,635 147,970 108,911 196,593 154,783 1992 ............................. 196,593 164,598 108,911 136,972 169,802 164,615 172,671 160,192 115,239 86,884 84,653 156,621 84,653 196,593 1,717,751 143,146 85,072 159,708 119,047 1993 ............................. 159,708 104,673 89,163 85,072 134,907 138,487 137,753 149,864 104,769 96,345 102,339 130,855 85,072 159,708 1,433,935 119,495 111,526 136,453 122,297 1994 ............................. 136,453 117,532 115,117 111,526 231,975 216,358 190,774 184,486 150,159 112,592 128,289 180,847 111,526 231,975 1,876,108 156,342 111,981 199,766 160,562 1995 ............................. 199,766 175,462 134,753 111,981 119,587 105,419 137,043 300,487 347,671 353,293 294,565 197,713 105,419 353,293 2,477,740 206,478 182,434 250,196 208,567 1996 ............................. 221,226 191,266 182,434 250,196 290,399 335,550 367,096 359,879 331,570 261,562 197,127 185,159 182,434 367,096 3,173,464 264,455 153,772 218,714 179,118 1997 ............................. 218,714 183,318 153,772 154,629 297,147 360,731 377,870 362,492 359,527 356,377 316,385 199,143 153,772 377,870 3,340,105 278,342 170,373 199,143 187,931 1998 ............................. 197,614 198,563 173,961 170,373 214,778 223,976 219,973 220,021 185,343 146,834 175,793 190,242 146,834 223,976 2,317,471 193,123 190,242 235,541 215,544 1999 ............................. 221,959 217,155 212,825 235,541 236,204 265,232 267,076 260,022 210,046 171,329 154,754 177,371 154,754 267,076 2,629,514 219,126 163,472 200,649 179,326 
145 

2000 ............................. 187,146 200,649 163,472 167,992 197,165 209,323 210,979 204,901 151,966 122,592 174,651 153,161 122,592 210,979 2,143,997 178,666 103,331 159,385 131,686 2001 ............................. 159,385 129,011 113,542 103,331 105,408 116,976 121,032 122,385 94,213 85,351 85,865 111,259 85,351 159,385 1,347,758 112,313 86,132 111,452 101,800 2002 ............................. 111,452 100,760 99,396 86,132 106,810 172,552 179,593 180,714 144,581 118,357 146,246 162,429 86,132 180,714 1,609,022 134,085 142,549 164,934 154,186 2003 ............................. 150,925 164,934 142,549 150,091 155,550 174,755 183,761 177,311 135,844 86,510 93,167 130,288 86,510 183,761 1,745,685 145,474 130,288 171,953 144,374 2004 ............................. 156,136 171,953 132,585 130,906 126,761 140,007 145,470 138,970 116,618 92,022 97,700 119,484 92,022 171,953 1,568,612 130,718 90,236 129,719 110,276 2005 ............................. 118,210 90,236 93,733 129,719 125,240 115,245 125,521 127,459 110,058 100,814 103,473 122,061 90,236 129,719 1,361,769 113,481 104,814 140,181 118,134 2006 ............................. 140,181 109,310 114,305 104,814 122,996 158,479 169,765 176,082 135,781 94,534 99,072 117,784 94,534 176,082 1,543,103 128,592 100,052 121,942 112,050 2007 ............................. 121,942 108,113 112,359 100,052 104,596 125,814 130,747 129,425 90,900 85,512 82,820 117,329 82,820 130,747 1,309,609 109,134 92,767 117,329 106,900 2008 ............................. 117,115 110,226 97,062 92,767 98,124 110,098 114,729 119,052 104,899 .............. .............. .............. 92,767 119,052 .................. .............. .............. .............. ..............

STATISTICS (JANUARY 1968 TO DECEMBER 2007) 

NUM .............................. 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 MIN ............................... 111,452 90,236 89,163 85,072 99,653 105,419 121,032 122,385 90,900 85,351 82,820 111,259 82,820 129,719 1,309,609 109,134 85,072 111,452 101,800 MEAN ............................ 207,049 196,995 176,341 167,352 190,433 204,135 217,525 217,662 183,565 172,542 175,046 184,404 130,426 251,968 2,293,048 191,087 150,835 215,467 184,154 MAX .............................. 278,471 273,173 274,214 339,180 355,277 360,731 377,870 362,492 359,527 356,377 316,385 270,807 222,627 377,870 3,350,271 279,189 238,366 339,180 265,772 STDEV ........................... 46,092 51,293 54,583 58,839 70,316 73,284 70,593 66,272 72,898 80,590 69,785 39,825 39,164 69,461 609,547 50,796 43,119 54,891 46,665 
146 

FIGURE 2–10.—Annual total gross energy generation at Garrison Dam (Source of 

data: USACE). 

FIGURE 2–11.—Monthly gross energy generation at Garrison Dam (Source of data: 

USACE). 
147 

FIGURE 2–12.—Gross energy generation at Garrison Dam; monthly mean, minimum 

and maximum for each year (Source of data: USACE). 

FIGURE 2–13.—Monthly gross energy generation at Garrison Dam, relative to total 

annual generation Highest mean generation occurred in December, July, and August (Source of data: USACE). 

2.4 Western Area Power Administration (WAPA) 

The Western Area Power Administration (WAPA) is an agency of the Department 

of Energy (Western). WAPA markets and transmits the power generated by the 

dams of the System by law at cost to non-profit preference power entities. Wholesale 

electrical power is transmitted through an integrated 17,000-circuit mile, high-voltage transmission system across 15 Western States including North Dakota, South 

Dakota, Nebraska, Utah, Nevada, California, and portions of Minnesota, Iowa, Kansas, Colorado New Mexico, Arizona, Texas, Wyoming, and Montana. The six projects 

in the System (including Garrison Dam and Oahe Dam) generated on average 8.3 

million MWh per year between fiscal year 1997 and 2007, ranging from 5.0 million 

MWH in 2007 to 13.9 MWh in 1997. 
148 

2.5 Benefits of System’s Hydropower Facilities 

The hydropower facilities of the System are beneficial to the region as they provide dependable cost-based energy to meet Western’s share of the annual peak 

power demands. Energy generated by these facilities have valuable characteristics 

that improve the reliability and efficiency of the electric power supply system, such 

as efficient peaking, a rapid rate of unit unloading, and rapid power availability for 

emergencies in the power grid (USACE, 2006). However, the limitations placed upon 

the power plant detailed above limits the plant from being an optimally efficient 

peaking facility. Another benefit is the fact that the facilities generate clean energy 

with a minimal carbon-footprint. 
149 

TABLE 2–3.—END-OF-MONTH ELEVATION OF LAKE OAHE, JUNE 1967 TO SEPTEMBER 2008 (IN FEET msl) 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN 

1967 ............................. ............ ............ ............ ............ ............ 1,598.3 1,599.5 1,601.5 1,602.8 1,604.2 1,606.2 1,606.9 ............ ............ ............ 1,606.9 1,609.0 1,608.4 1968 ............................. 1,608.7 1,609.0 1,608.8 1,608.8 1,607.4 1,606.7 1,603.3 1,601.0 1,599.9 1,602.8 1,604.7 1,604.7 1,599.9 1,609.0 1,605.5 1,604.7 1,615.6 1,609.4 1969 ............................. 1,605.1 1,608.8 1,612.8 1,615.6 1,615.8 1,613.7 1,614.3 1,610.4 1,607.6 1,606.2 1,606.7 1,607.9 1,605.1 1,615.8 1,610.4 1,605.7 1,608.7 1,607.3 1970 ............................. 1,606.5 1,607.6 1,605.7 1,608.7 1,612.5 1,612.8 1,610.0 1,607.5 1,605.1 1,604.9 1,605.9 1,604.5 1,604.5 1,612.8 1,607.6 1,604.5 1,615.5 1,609.6 1971 ............................. 1,606.1 1,608.5 1,613.4 1,615.5 1,616.7 1,616.2 1,614.7 1,610.5 1,607.2 1,604.9 1,602.2 1,601.2 1,601.2 1,616.7 1,609.8 1,601.2 1,609.8 1,605.3 1972 ............................. 1,602.4 1,603.9 1,609.0 1,609.8 1,614.4 1,615.8 1,614.4 1,610.2 1,606.4 1,602.6 1,601.0 1,599.9 1,599.9 1,615.8 1,607.5 1,599.9 1,608.8 1,604.3 1973 ............................. 1,602.3 1,603.1 1,607.3 1,608.8 1,608.5 1,607.8 1,606.1 1,603.4 1,602.4 1,602.2 1,603.8 1,604.4 1,602.2 1,608.8 1,605.0 1,604.4 1,609.2 1,607.1 1974 ............................. 1,605.7 1,607.2 1,609.2 1,608.9 1,608.6 1,608.0 1,606.1 1,604.5 1,602.6 1,603.1 1,603.7 1,605.1 1,602.6 1,609.2 1,606.1 1,604.7 1,609.8 1,606.8 1975 ............................. 1,604.7 1,606.7 1,607.7 1,609.8 1,612.9 1,614.5 1,616.6 1,617.1 1,613.5 1,608.7 1,604.8 1,605.0 1,604.7 1,617.1 1,610.2 1,604.9 1,606.5 1,605.8 1976 ............................. 1,604.9 1,606.5 1,606.2 1,606.5 1,607.5 1,609.0 1,608.1 1,606.7 1,603.9 1,603.5 1,604.0 1,603.9 1,603.5 1,609.0 1,605.9 1,603.9 1,608.2 1,606.3 1977 ............................. 1604.6 1607.4 1,608.2 1607.5 1606.3 1605.5 1602.6 1599.0 1596.9 1595.4 1594.5 1594.8 1594.5 1608.2 1601.9 1,594.8 1,614.7 1,603.5 1978 ............................. 1,596.9 1,600.7 1,610.3 1,614.7 1,615.7 1,615.4 1,615.0 1,613.4 1,610.4 1,607.0 1,605.6 1,604.6 1,596.9 1,615.7 1,609.1 1,604.6 1,614.3 1,608.4 1979 ............................. 1,605.9 1,607.1 1,610.0 1,614.3 1,615.3 1,615.9 1,615.2 1,613.4 1,611.6 1,608.2 1,606.0 1,605.1 1,605.1 1,615.9 1,610.7 1,604.3 1,608.1 1,606.3 1980 ............................. 1,604.3 1,606.2 1,607.9 1,608.1 1,605.9 1,605.0 1,603.1 1,600.0 1,598.0 1,597.2 1,596.8 1,598.1 1,596.8 1,608.1 1,602.6 1,597.8 1,602.0 1,599.8 1981 ............................. 1,599.7 1,601.4 1,602.0 1,597.8 1,594.7 1,595.0 1,595.5 1,594.2 1,592.6 1,591.1 1,591.6 1,591.4 1,591.1 1,602.0 1,595.6 1,591.4 1,604.9 1,597.7 1982 ............................. 1,592.6 1,597.2 1,602.3 1,604.9 1,610.2 1,612.5 1,612.9 1,610.8 1,607.9 1,607.8 1,608.5 1,607.7 1,592.6 1,612.9 1,606.3 1,605.8 1,614.4 1,609.3 1983 ............................. 1,605.8 1,607.4 1,611.4 1,614.4 1,616.0 1,615.9 1,615.8 1,613.8 1,612.6 1,609.8 1,607.6 1,605.7 1,605.7 1,616.0 1,611.4 1,605.7 1,613.3 1,609.9 1984 ............................. 1,608.4 1,610.7 1,611.4 1,613.3 1,615.6 1,618.3 1,616.8 1,613.8 1,610.2 1,608.9 1,606.7 1,605.2 1,605.2 1,618.3 1,611.6 1,605.2 1,611.0 1,608.2 1985 ............................. 1,606.1 1,608.6 1,611.0 1,610.0 1,609.7 1,608.2 1,605.4 1,603.2 1,601.7 1,601.2 1,599.2 1,598.9 1,598.9 1,611.0 1,605.S 1,598.9 1,616.4 1,606.5 1986 ............................. 1,601.4 1,603.9 1,611.9 1,616.4 1,617.4 1,617.0 1,615.4 1,612.7 1,610.8 1,609.6 1,608.7 1,605.7 1,601.4 1,617.4 1,610.9 1,604.2 1,614.6 1,608.5 1987 ............................. 1,604.2 1,606.1 1,612.1 1,614.6 1,613.7 1,613.3 1,611.6 1,610.1 1,607.8 1,605.7 1,604.0 1,604.5 1,604.0 1,614.6 1,609.0 1,604.0 1,606.7 1,605.4 1988 ............................. 1,604.0 1,606.2 1,606.7 1,605.5 1,604.7 1,603.0 1,600.3 1,597.0 1,592.8 1,590.3 1,588.6 1,589.1 1,588.6 1,606.7 1,599.0 1,589.1 1,593.2 1,591.1 1989 ............................. 1,589.5 1,591.2 1,593.2 1,592.5 1,590.9 1,589.3 1,587.5 1,584.7 1,583.2 1,581.0 1,583.8 1,583.9 1,581.0 1,593.2 1,587.6 1,583.9 1,590.7 1,588.1 1990 ............................. 1,587.8 1,589.5 1,590.7 1,588.8 1,588.1 1,589.2 1,588.2 1,586.1 1,583.5 1,581.2 1,582.2 1,582.2 1,581.2 1,590.7 1,586.5 1,582.2 1,587.9 1,585.3 1991 ............................. 1,583.4 1,586.0 1,587.9 1,587.2 1,588.5 1,592.9 1,591.2 1,588.5 1,583.3 1,584.9 1,586.5 1,587.6 1,583.3 1,592.9 1,587.3 1,587.6 1,592.2 1,590.3 1992 ............................. 1,589.3 1,591.5 1,592.2 1,591.1 1,590.4 1,589.8 1,590.0 1,590.1 1,591.4 1,591.0 1,591.8 1,591.6 1,589.3 1,592.2 1,590.9 1,591.6 1,597.9 1,594.2 1993 ............................. 1,592.2 1,592.7 1,596.4 1,597.9 1,600.2 1,601.9 1,608.0 1,610.4 1,610.7 1,610.3 1,609.8 1,609.5 1,592.2 1,610.7 1,603.3 1,607.6 1,611.6 1,609.5 1994 ............................. 1,608.2 1,607.6 1,611.6 1,610.6 1,610.6 1,610.2 1,610.0 1,608.1 1,606.3 1,605.2 1,603.8 1,603.7 1,603.7 1,611.6 1,608.0 1,603.7 1,610.6 1,606.8 1995 ............................. 1,604.0 1,607.0 1,608.6 1,610.6 1,616.7 1,618.4 1,616.2 1,613.3 1,612.3 1,611.1 1,609.5 1,608.2 1,604.0 1,618.4 1,611.3 1,607.9 1,613.1 1,610.6 1996 ............................. 1,607.9 1,611.1 1,612.8 1,613.1 1,616.9 1,618.5 1,617.5 1,616.0 1,615.3 1,613.5 1,609.3 1,607.5 1,607.5 1,618.5 1,613.3 1,607.5 1,617.9 1,612.2 1997 ............................. 1,607.7 1,609.9 1,617.9 1,617.9 1,617.6 1,617.8 1,618.3 1,617.1 1,616.5 1,615.3 1,612.4 1,609.8 1,607.7 1,618.3 1,614.9 1,607.7 1,609.8 1,608.8 1998 ............................. 1,607.7 1,608.4 1,608.2 1,609.7 1,609.7 1,611.5 1,612.2 1,612.2 1,610.6 1,609.5 1,609.3 1,607.4 1,607.4 1,612.2 1,609.7 1,606.4 1,611.1 1,608.4 1999 ............................. 1,606.4 1,607.9 1,609.2 1,611.1 1,615.6 1,617.0 1,616.9 1,617.0 1,614.7 1,610.9 1,607.4 1,606.9 1,606.4 1,617.0 1,611.8 1,605.4 1,607.3 1,606.6 
150 

TABLE 2–3.—END-OF-MONTH ELEVATION OF LAKE OAHE, JUNE 1967 TO SEPTEMBER 2008 (IN FEET msl)—Continued 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN 

2000 ............................. 1,605.4 1,606.4 1,607.0 1,607.3 1,607.3 1,606.2 1,604.8 1,602.5 1,599.5 1,598.3 1,597.3 1,597.1 1,597.1 1,607.3 1,603.3 1,597.1 1,604.8 1,600.0 2001 ............................. 1,597.7 1,598.4 1,601.9 1,604.8 1,607.7 1,608.8 1,608.7 1,605.8 1,603.0 1,601.2 1,599.4 1,598.5 1,597.7 1,608.8 1,603.0 1,596.2 1,598.9 1,598.1 2002 ............................. 1,598.6 1,598.9 1,598.2 1,596.2 1,595.3 1,592.7 1,590.8 1,588.1 1,586.4 1,585.1 1,583.4 1,584.8 1,583.4 1,598.9 1,591.5 1,584.8 1,588.2 1,586.6 2003 ............................. 1,585.3 1,587.2 1,588.2 1,587.5 1,588.7 1,587.4 1,586.5 1,584.4 1,581.0 1,578.2 1,576.7 1,576.9 1,576.7 1,588.7 1,584.0 1,576.9 1,582.1 1,579.5 2004 ............................. 1,577.6 1,579.2 1,582.1 1,581.6 1,578.4 1,576.8 1,574.3 1,572.1 1,573.2 1,574.8 1,576.0 1,575.8 1,572.1 1,582.1 1,576.8 1,574.4 1,576.2 1,575.3 2005 ............................. 1,575.2 1,576.2 1,574.4 1,574.7 1,576.5 1,577.6 1,576.4 1,573.1 1,572.9 1,573.9 1,575.6 1,575.3 1,572.9 1,577.6 1,575.2 1,575.3 1,577.6 1,576.8 2006 ............................. 1,576.8 1,577.6 1,576.7 1,577.4 1,577.0 1,575.8 1,573.4 1,570.3 1,571.4 1,572.6 1,573.2 1,572.8 1,570.3 1,577.6 1,574.6 1,572.3 1,577.7 1,574.3 2007 ............................. 1,572.9 1,572.3 1,575.8 1,577.7 1,580.5 1,582.8 1,581.4 1,580.1 1,580.9 1,580.8 1,582.3 1,582.2 1,572.3 1,582.8 1,579.1 1,581.8 1,583.2 1,582.5 2008 ............................. 1,582.3 1,581.8 1,583.2 1,582.8 1,584.7 1,592.6 1,593.9 1,592.4 1,593.1 ............ ............ ............ ............ ............ ............ ............ ............ ............

STATISTICS (JANUARY 1968 TO DECEMBER 2007) 

NUM ............................. 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 MIN ............................... 1,572.9 1,572.3 1,574.4 1,574.7 1,576.5 1,575.8 1,573.4 1,570.3 1,571.4 1,572.6 1,573.2 1,572.8 1,570.3 1,577.6 1,574.6 1,572.3 1,576.2 1,574.3 MEAN ............................ 1,598.8 1,600.6 1,603.0 1,603.8 1,604.7 1,604.9 1,603.9 1,601.8 1,600.0 1,598.7 1,598.1 1,597.7 1,595.3 1,606.5 1,601.3 1,597.3 1,603.6 1,600.3 MAX .............................. 1,608.7 1,611.1 1,617.9 1,617.9 1,617.6 1,618.5 1,618.3 1,617.1 1,616.5 1,615.3 1,612.4 1,609.8 1,607.7 1,618.5 1,614.9 1,607.9 1,617.9 1,612.2 STDEV ........................... 10.4 10.6 11.3 12.0 12.6 12.8 13.2 13.4 12.9 12.3 11.4 11.0 11.3 12.2 11.6 10.8 12.1 11.1 

1 Rows include Jan to Apr of following year. 
151 

FIGURE 2–14.—End-of month pool elevations in Lake Oahe between 1967 and the 

present (Source of data: USACE). 

FIGURE 2–15.—Annual end-of month pool elevations in Lake Oahe; monthly mean, 

minimum and maximum for each year (Source of data: USACE). 
152 

FIGURE 2–16.—Annual end-of month pool elevations in Lake Oahe; monthly mean, 

minimum and maximum in winter only (Dec–Feb) for each year (Source of data: 

USACE). 

Costs of power generation by the System’s facilities are very low compared to the 

costs of other types of energy generation facilities (coal, gas, oil, nuclear). WAPA 

conducts rate studies intermittently to adjust the rates for the power generated by 

the hydropower dams in the System. Rates have gradually increased from approximately $5/MWh in 1973 to $18/MWh in 2007. Based on these rates, the revenue 

from net energy generated at Garrison Dam has increased from approximately $12 

million in 1973 to $24 million in 2007 (Figure 2–17). Highest revenues were 

achieved in 1996 as a result of high rainfall in the watershed which led to higher 

energy generation. Highest demand for hydropower exists in summer and in winter; 

higher energy generation in these months consequently results in higher revenues 

(Figure 2–18). 

FIGURE 2–17.—Annual revenues for net energy generated by Garrison Dam between 

fiscal year 1973 and fiscal year 2007 (Sources of input data: USACE). 
153 

FIGURE 2–18.—Mean monthly revenue generated by Garrison Dam for fiscal year 

2005 through fiscal year 2007 (Source of input data: USACE). 

3.0 SILTATION IMPACTS ON HYDROPOWER OPERATIONS 

Potential impacts from siltation in the Missouri River on hydropower operations 

in North Dakota consist of the following: 

—Loss of storage in Lake Sakakawea 

—Entrainment of sediment into the turbines at Garrison Dam 

—Reduced releases at Garrison Dam in winter due to flooding risk from sediment 

aggradation 

3.1 Loss of Storage in Lake Sakakawea 

3.1.1. Sediment Sources 

Sediment enters the reservoir primarily via the Missouri River and its tributaries. 

Another source is shoreline erosion. Due to the size of Lake Sakakawea, nearly all 

of the sediment that enters the reservoir remains there as sediment deposits. The 

USGS (1995) considers the trapping efficiency 100 percent, with only negligible 

amounts of suspended sediment being transported beyond Garrison Dam. 

The drainage area of Lake Sakakawea is 181,400 square miles. Excluding the 

drainage area of the Fort Peck Lake, which traps the sediment of its own watershed, the drainage area for Lake Sakakawea is 123,900 square miles. 

The largest point sources for sediment to Lake Sakakawea are the Missouri River 

and especially the Yellowstone River, a tributary to the Missouri River (Figure 2– 

3). The headwaters of the 678-mile long Yellowstone River are in Wyoming and 

Montana. The lower 18 miles of the Yellowstone River are within North Dakota. 

The Yellowstone River joins with the Missouri River at RM 1581. Downstream from 

the confluence, the Missouri River is free-flowing until up to the headwaters of Lake 

Sakakawea. The free-flowing stretch of the Missouri River depends upon Lake 

Sakakawea’s elevation; the length of this free-flowing stretch may be as little as 15 

miles (e.g., in year 1997) to as many as 50 miles (e.g., in year 1991) (NDGFD, 2002). 

Sediment from mainly the Missouri River and the Yellowstone River has buried the 

old river channel downstream of approximately RM 1535. 

The Yellowstone River is largely unregulated, with only two dams in the headwaters (Yellowtail Dam and Boysen Dam; Figure 2–3). The mean annual flow of the 

Yellowstone River at its lowest gaging station (at Sidney, Montana) was determined 

as 12,250 cfs, with a maximum instantaneous flow estimated at 159,000 cfs in June 

1921 (NDGFD, 2002). Some of the highest stages in the river were caused by ice 

dams. The construction of upstream water depletion projects have reduced flows in 

the Yellowstone River by approximately 24 percent from historical levels. In comparison, annual flows of the Missouri River at its lowest gaging station above the 

confluence with the Yellowstone River, located in Culbertson, Montana, have aver-
154 

aged 10,270 cfs. The peak flow in the Missouri River after closure of Fort Peck Dam 

was 78,200 cfs on March 1943. 

The mean grain size of the suspended sediment in the Missouri River at 

Culbertson, Montana, near the border with North Dakota, was measured as 45 percent sand, 50 percent silt, and 5 percent clay (USACE, 1978, as listed in Wuebben 

and Gagnon, 1995). The corresponding grain sizes in the Yellowstone River at Sidney, Montana, were 35 percent, 60 percent and 5 percent, respectively. The mean 

grain size (D50) of the bed material was 0.28 mm in the Missouri River at 

Culbertson, and 0.25 mm in the Yellowstone River at Sidney. Both mean grain sizes 

fall into the ‘‘medium sand’’ category which has a size range of 0.25 to 0.50 mm. 

The USACE (1978) estimated the sediment load from the Missouri River at 

Culbertson, Montana, with 13.5 million tons/year. A much greater load (41.5 million 

tons/year) was estimated to be supplied to Lake Sakakawea by the Yellowstone 

River at Sidney near the confluence with the Missouri River. According to preliminary studies by the USGS (as mentioned in Wuebben and Gagnon, 1995), these 

loads (total of 55 million tons/year) may have been overestimated by 30 percent. 

Sediment contributed by the Missouri River includes sediment that is eroded from 

the river’s bank and bottom, downstream of the Fort Peck dam. 

The USACE (1993a) estimated that the gross storage loss for all of Lake 

Sakakawea since closure of the dam in 1953 and the survey date in 1988 was 

907,000 acre-feet or 25,900 acre feet/year. Using a bulk density of 1.4 g/cm3, based 

on values provided by Geiger (1963) for sand and silt, this volume translates into 

a sediment supply of 45 million tons/year. This volume is similar to the volume discussed above in Wuebben and Gagnon (1995), after allowing for a 30 percent reduction as suggested. 

Additional riverine sediment sources to Lake Sakakawea are numerous small tributaries such as the Little Missouri River, and shoreline erosion in the lake. Shoreline erosion occurs primarily as a result of waves acting on bluffs and other erodible 

topographic features. The likelihood of shoreline erosion is highest during periods 

of high water elevations in the reservoir. The relative contribution of shoreline erosion to the total sediment load entering Lake Sakakawea is considered to be very 

small, however (John Remus, pers. communication, November 21, 2008). 

3.1.2. Sediment Deposition in Lake Sakakawea 

Lake Sakakawea extends close to the border of North Dakota with Montana. Sediment initially accumulated in the lower elevation zones during the filling of Garrison Lake. In 1993, the USACE estimated that 3.5 percent of the capacity in the Permanent Pool was lost. 

Since the pool was filled, sediments carried by the Missouri River settle out in 

the calmer headwaters of Lake Sakakawea. This deposition has resulted in a progressive loss of the channel capacity as well as in an upward shift of the stage-discharge relationship. Already the upper reach of the lake is silted in heavily. New 

sediment islands form continuously over time and gradually migrate downgradient 

(Figure 3–1). However, the aggradation is largely confined to the upper reaches of 

the reservoir (Figures 3–2 to 3–4). This is also reflected in USACE (1993a): 

‘‘. . . the location of the sediment deposits vary significantly longitudinally 

throughout the reservoirs [of the System]. The majority of the sediment begins to 

settle out 10 to 15 miles downstream from the upstream end of the pools, and is 

concentrated within a 30-mile reach downstream from this point. Sediment deposits 

of any significant quantity have not been observed in the vicinity of the dams and/ 

or powerhouses at any of the six dams [of the System]. Most of the sediment that 

presently exists in the lower elevation zones of the pools was deposited during the 

reservoir filling period, and little change has been noted... since the projects 

were first filled.’’ (p. 6) 

As stated above, the USACE (1993a) estimated that the gross storage loss for all 

of Lake Sakakawea since closure of the dam in 1953 and the survey date in 1988 

was 907,000 acre-feet or 25,900 acre-feet/year. In the 20 years since that time, sedimentation has continued in the upper reaches of Lake Sakakawea. Assuming that 

the sediment accumulation rate from 1993 also applies for the period since the 1988 

survey, an additional 518,000 acre-feet would have been deposited in Lake 

Sakakawea by year 2008. Accordingly, the total sediment load that has been deposited in the reservoir between 1953 and 2008 (55-year time span) is 1,425,000 acrefeet. This volume translates to a loss in storage volume of 6 percent of Lake 

Sakakawea at the Maximum Operating Pool level (1,854 feet msl), or 0.11 percent 

per year. 
155 

FIGURE 3–1.—Upper Lake Sakakawea area, showing sediment aggradation. (The 

aerial photo is from June 23, 2003 (Source: Google Earth). 

FIGURE 3–2.—Changes in thalweg elevations in Lake Sakakawea, 1956 and 1987 

(USACE, 1993a). 
156 

FIGURE 3–3.—Changes in average bed elevations in Lake Sakakawea, 1956 and 1987 

(USACE, 1993a). 

FIGURE 3–4.—Changes in volume in Lake Sakakawea between 1956 and 1988 

(USACE, 1993a). 

The actual loss might be slightly lower as a result of increased equilibration of 

the Missouri River channel between Fort Peck and the upper Lake Sakakawea, resulting in gradually decreasing erosion rates over time. 

Using a uniform sediment aggradation rate, these values suggest that Lake 

Sakakawea would be filled completely with sediment 900 years after construction 

of the Garrison Dam. This value is only first-order approximation as it does not consider variables such as sediment trapping efficiency, climate variability over time, 

or potential sediment contributions from the watershed of Fort Peck Lake (which 

may be filled before Lake Sakakawea): 

—Sediment Trapping Efficiency.—This first-order calculation assumes a continuous trapping efficiency of 100 percent. In reality, however, the trapping effi-
157 

ciency will gradually decrease toward the end of the life expectancy for the reservoir, and sediment will start to be transported passed Garrison Dam. 

—Climate Variability Over Time.—Nine hundred years is a long time during 

which the regional climate is expected to vary over the short and long term. Decreasing precipitation in the Lake Sakakawea watershed will result in less sediment erosion and hence a longer life expectancy of the reservoir, and vice versa. 

—Sediment Contributions From the Watershed of Fort Peck Lake.—Like Lake 

Sakakawea, Fort Peck Lake most likely captures nearly all of the sediment of 

its watershed. When the lake eventually fills with sediment, this sediment will 

bypass Fort Peck Dam and also enter Lake Sakakawea. Comparisons between 

1938 and 1986 lake bed data demonstrate that there was a storage loss of 

869,000 acre-feet, or 18,100 acre-feet/year (USACE, 1993a). Assuming the same 

loss rate for years 1987 to 2008, an added 398,000 acre-feet would have been 

lost. Therefore, the total loss to-date since construction would be 1,267,000 acrefeet. The volume represents a 6.8 percent loss of the gross storage volume of 

Fort Peck Lake of 18,688,000 acre-feet since construction 70 years ago (i.e., 0.10 

percent per year). This loss rate is very similar to the loss rate of Lake 

Sakakawea (0.11 percent per year), suggesting a similar first-order life expectancy of 900 years. Based on these data, sediment from the Fort Peck Lake watershed will not reach Lake Sakakawea for many centuries. 

3.2 Entrainment of Sediment into the Turbines at Garrison Dam 

Impacts to the hydropower operation will start to occur well before Lake 

Sakakawea has filled with sediment. However, with an annual loss of storage capacity by 0.11 percent, and most of the deposition occurring in the upper reaches of 

the reservoir, impacts to the intakes to the hydropower facility are not expected for 

a long time. As a result, the USACE does not have any specific sediment management methods or sediment control facilities at their hydroelectric facilities at this 

time (Bill Mulligan, personal communication; November 13, 2008). 

Eventually, impacts will consist of clogging of the intake and abrasion of the turbine blades by coarser sediment grains. The start date for these impacts depends 

on parameters such as grain size, water elevation in the reservoir over time, frequency of drought conditions (which will bring sediment further into the lake), geometry of the lake, flows velocities in front of the intake to the turbines, and elevation of the intake in the water column relative to the elevation of the reservoir. 

Based on the existing information, including USACE (1993a), most of the sediment 

carried into the lake by the Missouri River remains as delta deposits in the headwaters of the lake. Thus, only the finest particles that can remain in suspension for 

a long time are transported further downstream at present. As a rough first-order 

estimate, we anticipate that effects on the turbines from sediment deposition in the 

reservoir will be negligible for at least the next 200 years. However, a more detailed 

assessment must be performed if a more accurate estimate is desired. 

3.3 Reduced Releases at Garrison Dam in Winter due to Flooding Risk 

Siltation in the reach between Garrison Dam and Lake Oahe has resulted in increased risk of flooding in the downstream reach between the dam and the headwater of Oahe Lake. The Missouri River typically freezes in December (‘‘ice-in’’; 

‘‘freeze-up’’). It remains frozen in January and February, and starts to thaw in 

March and April (‘‘ice-out’’; ‘‘break-up’’) (Jody Farhat, pers. communication, November 14, 2008). A large consideration in flow releases are ice dams (Figure 3–5). Ice 

dams can form during freeze-up as well as during break-up (FEMA, 2005). Ice-in 

starts at the headwaters of Lake Oahe, and moves upstream toward Garrison Dam. 

Break-up ice dams normally occur in late winter or early spring during the melting 

period. These break-up ice dams are most common downstream of the confluence between the Missouri River and the Heart River (RM 1311) (Figure 3–6). According 

to FEMA (2005), these ice dams form mostly because of high flows in the Heart 

River during snowmelt or spring rains while the Missouri River is still covered with 

ice. Siltation in the river indirectly worsens such flooding, as the ice sheet in the 

Missouri River is at a higher elevation than it would be without aggradation. 

In order to minimize the flooding risk, specifically in the Bismarck/Mandan area, 

the USACE releases water from Lake Sakakawea in the following manner: 

—Ice-in (December).—The USACE releases water at a reduced rate while the ice 

is forming on the river. The gradually forming ice creates a ‘‘conduit’’ for the 

released water underneath it. Initially the ice surfaces are rough and ‘‘chunky’’, 

resulting in a higher risk of flooding. As a result, release rates have been reduced to as low as 16,000 cfs in past years as the ice sheet build-up advances 

upstream from the headwaters of Lake Oahe. 
158 

—January–December.—After the ice has formed on the river, it is smoothed on its 

underside by the flowing water, allowing for an increase in the release rate at 

Garrison Dam. The rate is set in a manner that prevents flow over the ice or 

the breakup of the ice which could cause ice dams. As specified in the Master 

Water Control Manual, release rates are not normally scheduled above 20,000 

cfs in December (USACE, 2006). However, based on experience, water release 

rates of 27,000 cfs are possible. This maximum winter release rate is a reduction of the original capacity of 35,000 cfs, as a result of aggradation of the river 

in the headwaters of Lake Oahe. 

—Ice-out (April–March).—The breaking up of the ice presents a risk to flooding 

as the moving ice can cause ice dams that block the flow of water. In addition, 

rainfall events may result in high discharges from the tributaries to the Missouri River in the reach between Garrison Dam and Lake Oahe. These tributary 

discharges are often coupled with melting snow from the watershed. The two 

largest tributaries are the Heart River and Knife River. Planned winter flow releases at Garrison Dam consider flows in these tributaries. 

FIGURE 3–5.—Longitudinal profile of typical break-up ice jam (Wuebben and 

Gagnon, 1995). 
159 

2The USGS gaging station is located upstream in Bismarck. The Heart River and Apple 

Creek enter the Missouri River downstream of the USGS gage. Their mean annual discharge 

rate is 267 cfs and 45 cfs, respectively. Thus, these two streams contribute an additional 1.3 

percent to the flow of the Missouri River, before the Missouri River enters Lake Oahe. 

FIGURE 3–6.—Sediment aggradation along the Missouri River between the cities of 

Bismarck and Mandan, and the headwaters of Lake Oahe (Source: Google Earth). 

3.3.1. Flows 

The mean annual outflow from Lake Sakakawea between 1967 (2 years after the 

reservoir was filled) and 2007 was 15.6 million acre-feet (Table 3–1), which translates into a mean daily flow rate of 21.5 million cfs (Table 3–2). The annual outflow 

ranged from a minimum of 9.6 million acre-feet in both 1993 and 2001, to a maximum of 25.2 million acre-feet in 1997 (Figure 3–7). Releases from recent years were 

close to the minimum due to a drought in the upper Missouri watershed. 

Most of the inflow to Lake Oahe comes from water releases at Garrison Dam. A 

gaging station is maintained along the Missouri River at Bismarck (USGS Station 

06342500), operated in cooperation with the USACE. Discharge data at Bismarck 

reflect the gradual filling of Lake Sakakawea until the late 1960s (Figures 3–8 and 

3–9; Table 3–3). Thereafter, the discharge rate in the Missouri River gradually decreased until 1995, as also observed in power generation records and Garrison Dam 

release flows. Discharge rates in 1996 and 1997 were very high due to high runoff 

in the Upper Missouri River watershed. The discharge rates decreased in the subsequent years to their currently lowest level since the Lake Sakakawea was closed 

(Figure 2–7). The decrease in flow over the 20 year period between 1968 and 2007 

was on average 50 percent less (Figure 3–10). 

As expected, the discharge data between Bismarck (USGS data) and Garrison 

Dam (USACE data) coincide well (Figure 3–11). Peak discharges were slightly higher at Bismarck due to tributary runoff downstream of Garrison Dam (Figure 3–12). 

In general, the flow at Bismarck was 8.3 percent 2 higher compared to release flows 

at Garrison Dam between 1967 and 2007 (Figure 3–13). This percentage was higher 

(13.3 percent) during the ice-out period (March–April), presumably due to snowmelting in the watershed downstream of Garrison Dam. In specific years, the flow 

at Bismarck was higher by as much as 45 percent compared to release flows at Garrison Dam, which underscores the importance of managing releases at Garrison 

Dam to prevent flooding in Bismarck and Mandan (Figure 3–14). 

The annual runoff peak typically occurs in June. The highest monthly releases 

occur in July and August (Figure 3–15). The lowest releases occur during the fall 

(October and November). 

A rating curve at the Bismarck gaging station indicates that there have been 

major changes in the stage at this location for flows exceeding 30,000 cfs. Such flows 
160 

caused an upward trend of 1 to 2 feet (Figure 3–16). This increase has caused flooding in the winter in some of the lower lying housing areas near Bismarck (USACE, 

2004c). According to Mr. Ronald Sando (personal communication November 12, 

2008), flooding can occur in Bismarck, south of the Bismarck Expressway. There has 

also been flooding in the past in the city of Mandan along the western bank of the 

Missouri River. 

3.3.2. Sedimentation 

The headwaters of Lake Oahe reach almost up to the city of Bismarck. Sediment 

deposition has occurred in the headwaters of Lake Oahe, just as it has in the headwaters of Lake Sakakawea (USACE, 1993b). The highest aggradation of sediment 

occurred in an area approximately 10 miles to the south of Bismarck (Berger, 2008). 

The sediment delta that formed in Lake Oahe has affected the river’s flood stage 

in Bismarck and Mandan. At construction, the open-water channel capacity for a 

stage of 13 feet was 90,000 cfs (USACE, 2006). In 1975, just 20 years later, this 

capacity had been reduced to 50,000 cfs. 

Releases at Garrison Dam result in erosion of sediment just downstream of the 

dam (USGS, 1995; Biedenharn et al., 2001). The river stabilizes further downstream 

as erosion of sediment is balanced by sediment resupplied from upstream sources. 

As flow velocities decrease, the carrying capacity of the river decreases as well. Sediments, both carried in suspension and as bedload, eventually settle out resulting in 

aggradation of the river. A study of the sedimentation from 1958 to 1985 was conducted by the USACE from RM 1390 (Garrison Dam) to RM 1336 (20 miles north 

of Bismarck) (USACE, 1993c). The study found that the thalweg and average bed 

elevations had decreased at most locations (Table 3–4). The widths of the channel 

varied. Tailwater elevations at Garrison Dam had decreased by approximately 7 feet 

between 1956 and 2003 (USACE, 2004c; Figure 3–17). Erosion in the Missouri River 

downstream of Garrison Dam was also shown from investigations along 21 transects 

by the USGS conducted between Garrison Dam and Lake Oahe between 1988 and 

1991 (USGS, 1995). 

The USGS (1995) also observed erosion along transects located in Bismarck and 

6 miles to the south of Bismarck. This erosion was likely the result of degradation 

of sediment that had previously been deposited in the headwater of Lake Oahe. The 

elevations in Lake Oahe were lower during the study period (1988 to 1991) than 

during earlier years (Figure 2–14). However, elevations have fluctuated since then 

with higher elevations in the mid-1990s and again low elevations in recent years 

due to drought in the watershed. Bruce Engelhardt also stated that sedimentation 

in the Missouri River occurs at times in the Bismarck area (personal communication, November 13, 2008). 

It is expected that the river will continue to erode sediment in the upper Garrison 

Reach. Erosion will continue from degradation as well as from meandering of the 

channel, although these processes may gradually decrease over time. Williams and 

Wolman (1984, as reported in USGS [1995]) estimated that 95 percent equilibrium 

would be reached within 2 to 90 years after completion of a dam, based on a study 

of 21 dams constructed on alluvial rivers, mostly in the semiarid western United 

States. Site-specific data for this reach of the Missouri River were not located, however, in order to narrow down this wide range. 

In urban areas such as Bismarck and Mandan, the river channel has no room to 

widen without affecting properties. Therefore, aggradation within the river at this 

location results in an increased risk of flooding and the loss of property. Potential 

buyouts due to flooding concerns in the Bismarck-Mandan area are estimated at 

over $100 million (Remus, 2008). The impact of flooding is estimated to be greatest 

between RM 1300 and 1316, i.e., in downtown Bismarck and Mandan (FEMA, 2005). 

Flooding also occurs outside of urbanized areas, affecting cropland and causing soil 

erosion. Since flooding from ice dams occurs in winter, there are no crops that could 

be damaged, however. 
161 

TABLE 3–1.—MONTHLY OUTFLOW FROM LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN 1,000 ACRE-FEET) 

[Retrieved on 8–October–2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN TOTAL MIN MAX MEAN TOTAL 

1967 ......................................................... ............ ............ ............ ............ ............ 1,574 1,917 2,210 1,560 1,826 1,594 1,635 ............ ............ ............ ............ 1,176 1,739 1,518 7,588 1968 ......................................................... 1,739 1,717 1,176 1,321 1,224 990 1,006 1,219 1,366 1,897 1,439 1,551 990 1,897 1,387 16,645 1,504 1,881 1,723 8,617 1969 ......................................................... 1,810 1,871 1,881 1,504 1,442 1,044 1,630 1,790 1,522 1,514 1,526 1,815 1,044 1,881 1,612 19,349 1,233 1,815 1,541 7,704 1970 ......................................................... 1,616 1,554 1,233 1,486 1,706 1,642 1,610 1,648 1,293 1,626 1,655 1,474 1,233 1,706 1,545 18,543 1,474 2,066 1,744 8,720 1971 ......................................................... 1,863 1,591 1,726 2,066 2,337 2,071 2,134 1,611 1,386 1,444 1,485 1,467 1,386 2,337 1,765 21,181 1,467 2,232 1,753 8,763 1972 ......................................................... 1,764 1,656 1,644 2,232 2,367 2,214 1,648 1,412 1,214 1,305 1,326 1,401 1,214 2,367 1,682 20,183 1,195 1,645 1,437 7,183 1973 ......................................................... 1,645 1,393 1,549 1,195 1,037 1,104 1,225 1,268 1,167 1,157 1,172 1,401 1,037 1,645 1,276 15,313 1,146 1,604 1,435 7,175 1974 ......................................................... 1,604 1,481 1,543 1,146 1,283 1,404 1,589 1,680 1,378 1,747 1,446 1,500 1,146 1,747 1,483 17,801 1,041 1,578 1,401 7,007 1975 ......................................................... 1,358 1,578 1,530 1,041 1,959 2,388 3,800 3,328 2,216 1,994 1,964 1,716 1,041 3,800 2,073 24,872 1,598 1,894 1,725 8,626 1976 ......................................................... 1,598 1,812 1,606 1,894 2,198 2,230 2,244 1,921 1,545 1,547 1,761 1,464 1,464 2,244 1,818 21,820 957 1,803 1,406 7,030 1977 ......................................................... 1,803 1,552 1,254 957 971 920 1,069 999 866 774 972 1,298 774 1,803 1,120 13,435 1,031 1,689 1,371 6,855 1978 ......................................................... 1,689 1,614 1,223 1,031 974 1,829 2,365 2,346 1,932 1,949 1,978 1,424 974 2,365 1,696 20,354 1,424 1,876 1,664 8,318 1979 ......................................................... 1,876 1,690 1,678 1,650 2,247 2,165 1,597 1,294 1,037 927 838 1,194 838 2,247 1,516 18,193 1,187 1,668 1,412 7,059 1980 ......................................................... 1,380 1,668 1,630 1,187 1,132 1,235 1,603 1,453 1,291 1,364 1,443 1,305 1,132 1,668 1,391 16,691 980 1,539 1,347 6,734 1981 ......................................................... 1,539 1,534 1,376 980 1,071 1,491 1,733 1,401 1,144 920 899 1,163 899 1,733 1,271 15,251 1,018 1,741 1,426 7,130 1982 ......................................................... 1,594 1,741 1,614 1,018 1,483 1,356 1,551 1,240 1,042 1,135 1,755 1,370 1,018 1,755 1,408 16,899 1,238 1,734 1,458 7,289 1983 ......................................................... 1,238 1,637 1,734 1,310 1,025 1,066 1,080 1,611 1,350 837 986 1,340 837 1,734 1,268 15,214 956 1,652 1,325 6,624 1984 ......................................................... 1,652 1,531 1,145 956 839 831 1,350 1,672 1,523 1,438 1,502 1,330 831 1,672 1,314 15,769 1,042 1,645 1,358 6,789 1985 ......................................................... 1,645 1,601 1,171 1,042 1,139 1,190 1,188 1,117 1,008 830 923 1,338 830 1,645 1,183 14,192 1,140 1,595 1,414 7,072 1986 ......................................................... 1,595 1,454 1,545 1,140 649 890 1,167 1,466 1,148 1,332 1,424 1,227 649 1,595 1,253 15,037 630 1,499 1,166 5,831 1987 ......................................................... 1,452 1,499 1,023 630 942 1,069 1,128 1,118 969 802 766 1,234 630 1,499 1,053 12,632 1,089 1,502 1,266 6,328 1988 ......................................................... 1,313 1,502 1,190 1,089 1,146 1,136 1,177 1,109 816 661 664 1,127 661 1,502 1,078 12,930 940 1,250 1,097 5,484 1989 ......................................................... 1,174 1,250 993 940 1,273 1,333 1,378 1,342 770 675 1,131 1,225 675 1,378 1,124 13,484 927 1,489 1,153 5,767 1990 ......................................................... 1,489 1,075 927 1,051 1,180 1,201 1,211 1,117 654 616 683 1,061 616 1,489 1,022 12,265 767 1,265 1,059 5,297 1991 ......................................................... 1,265 1,170 767 1,034 1,195 1,143 1,187 1,186 818 810 843 1,162 767 1,265 1,048 12,580 775 1,374 1,092 5,461 1992 ......................................................... 1,374 1,173 775 977 1,185 1,156 1,183 1,115 807 612 601 1,121 601 1,374 1,007 12,079 612 1,158 859 4,293 1993 ......................................................... 1,158 764 638 612 937 933 908 971 672 612 652 833 612 1,158 808 9,690 695 877 778 3,889 1994 ......................................................... 877 749 735 695 1,435 1,323 1,168 1,134 932 704 806 1,137 695 1,435 975 11,695 730 1,282 1,028 5,140 1995 ......................................................... 1,282 1,124 867 730 775 659 813 1,832 2,199 2,209 1,852 1,244 659 2,209 1,299 15,586 1,131 1,677 1,335 6,674 1996 ......................................................... 1,409 1,213 1,131 1,677 2,246 2,106 2,252 2,218 2,091 1,615 1,231 1,171 1,131 2,252 1,697 20,360 965 1,407 1,140 5,699 1997 ......................................................... 1,407 1,170 986 965 1,916 2,524 3,523 3,069 2,771 3,040 2,520 1,345 965 3,523 2,103 25,236 1,155 1,368 1,282 6,409 1998 ......................................................... 1,354 1,368 1,187 1,155 1,489 1,529 1,476 1,476 1,260 1,051 1,220 1,287 1,051 1,529 1,321 15,852 1,287 1,615 1,472 7,361 1999 ......................................................... 1,521 1,483 1,455 1,615 1,611 1,769 1,761 1,714 1,393 1,157 1,040 1,203 1,040 1,769 1,477 17,722 1,128 1,385 1,231 6,154 
162 

TABLE 3–1.—MONTHLY OUTFLOW FROM LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN 1,000 ACRE-FEET)—Continued 

[Retrieved on 8–October–2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN TOTAL MIN MAX MEAN TOTAL 

2000 ......................................................... 1,277 1,385 1,128 1,161 1,371 1,445 1,448 1,422 1,068 874 1,246 1,111 874 1,448 1,245 14,936 744 1,155 948 4,741 2001 ......................................................... 1,155 940 791 744 756 823 848 859 680 627 630 793 627 1,155 804 9,646 642 804 748 3,742 2002 ......................................................... 804 735 768 642 787 1,243 1,279 1,300 1,043 852 1,071 1,207 642 1,300 978 11,731 1,066 1,240 1,151 5,755 2003 ......................................................... 1,133 1,240 1,066 1,109 1,151 1,265 1,319 1,296 1,003 663 699 979 663 1,319 1,077 12,923 979 1,330 1,104 5,522 2004 ......................................................... 1,181 1,330 1,024 1,008 969 1,071 1,103 1,059 894 707 758 934 707 1,330 1,003 12,038 721 1,035 877 4,384 2005 ......................................................... 950 721 744 1,035 1,014 893 933 954 840 773 797 945 721 1,035 883 10,599 819 1,097 922 4,611 2006 ......................................................... 1,097 859 891 819 942 1,181 1,265 1,353 1,078 743 782 943 743 1,353 996 11,953 802 980 902 4,512 2007 ......................................................... 980 877 910 802 820 955 980 984 692 666 645 915 645 984 852 10,226 744 924 849 4,247 2008 ......................................................... 924 879 785 744 790 853 837 854 748 ............ ............ ............ ............ ............ ............ ............ ............ ............ ............ ............

STATISTICS (JANUARY 1968 TO DECEMBER 2007) 

NUM .......................................................... 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 MIN ........................................................... 804 721 638 612 649 659 813 859 654 612 601 793 601 984 804 9,646 612 804 748 3,742 MEAN ........................................................ 1,417 1,358 1,206 1,141 1,306 1,370 1,498 1,478 1,222 1,155 1,178 1,244 877 1,754 1,298 15,573 1,024 1,484 1,260 6,300 MAX .......................................................... 1,876 1,871 1,881 2,232 2,367 2,524 3,800 3,328 2,771 3,040 2,520 1,815 1,464 3,800 2,103 25,236 1,598 2,232 1,753 8,763 STDEV ....................................................... 277 321 342 376 476 480 632 522 472 545 460 223 229 577 329 3,943 257 328 277 1,383 

1 Rows include Jan to Apr of following year. 

TABLE 3–2.—AVERAGE DAILY OUTFLOW FOR THE MONTH FROM LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN 1,000 cfs) 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN 

1967 ..................................................................................... ............ ............ ............ ............ ............ 26.5 31.2 35.9 26.2 29.6 26.8 26.6 ............ ............ ............ 19.1 29.8 25.2 1968 ..................................................................................... 28.3 29.8 19.1 22.2 19.9 16.6 16.4 19.8 23.0 30.9 24.2 25.2 16.4 30.9 23.0 25.2 33.7 28.8 1969 ..................................................................................... 29.4 33.7 30.6 25.3 23.4 17.5 26.5 29.1 25.6 24.6 25.6 29.5 17.5 33.7 26.7 20.1 29.5 25.8 1970 ..................................................................................... 26.3 28.0 20.1 25.0 27.7 27.6 26.2 26.8 21.7 26.4 27.8 24.0 20.1 28.0 25.6 24.0 34.7 29.2 1971 ..................................................................................... 30.3 28.7 28.1 34.7 38.0 34.8 34.7 26.2 23.3 23.5 24.9 23.9 23.3 38.0 29.3 23.9 37.5 29.1 1972 ..................................................................................... 28.7 28.8 26.7 37.5 38.5 37.2 26.8 23.0 20.4 21.2 22.3 22.8 20.4 38.5 27.8 20.1 26.8 24.0 
163 

1973 ..................................................................................... 26.8 25.1 25.2 20.1 16.9 18.6 19.9 20.6 19.6 18.8 19.7 22.8 16.9 26.8 21.2 19.3 26.7 24.0 1974 ..................................................................................... 26.1 26.7 25.1 19.3 20.9 23.6 25.8 27.3 23.2 28.4 24.3 24.4 19.3 28.4 24.6 17.5 28.4 23.5 1975 ..................................................................................... 22.1 28.4 24.9 17.5 31.9 40.1 61.8 54.1 37.2 32.4 33.0 27.9 17.5 61.8 34.3 26.0 31.8 28.7 1976 ..................................................................................... 26.0 31.5 26.1 31.8 35.7 37.5 36.5 31.2 26.0 25.2 29.0 23.8 23.8 37.5 30.0 16.1 29.3 23.5 1977 ..................................................................................... 29.3 28.0 20.4 16.1 15.8 15.5 17.4 16.2 14.6 12.6 16.3 21.1 12.6 29.3 18.6 17.3 29.1 23.0 1978 ..................................................................................... 27.5 29.1 19.9 17.3 15.8 30.7 38.5 38.3 32.5 31.7 33.2 23.2 15.8 38.5 28.1 23.2 30.5 27.8 1979 ..................................................................................... 30.5 30.4 27.3 27.7 36.5 36.4 26.0 21.0 17.4 15.1 14.1 19.4 14.1 36.5 25.2 19.4 29.0 23.4 1980 ..................................................................................... 22.4 29.0 26.5 19.9 18.4 20.8 26.1 23.6 21.7 22.2 24.2 21.2 18.4 29.0 23.0 16.5 27.6 22.5 1981 ..................................................................................... 25.0 27.6 22.4 16.5 17.4 25.1 28.2 22.8 19.2 15.0 15.1 18.9 15.0 28.2 21.1 17.1 31.4 23.9 1982 ..................................................................................... 25.6 31.4 26.3 17.1 24.1 22.8 25.2 20.2 17.5 18.5 29.5 22.3 17.1 31.4 23.4 20.1 29.5 24.4 1983 ..................................................................................... 20.1 29.5 28.2 22.0 16.7 17.9 17.6 26.2 22.7 13.6 16.6 21.8 13.6 29.5 21.1 16.0 26.9 22.0 1984 ..................................................................................... 26.9 26.6 18.6 16.0 13.7 14.0 22.0 27.1 25.6 23.4 25.2 21.6 13.7 27.1 21.7 17.5 28.8 22.7 1985 ..................................................................................... 26.7 28.8 19.0 17.5 18.5 20.0 19.3 18.2 16.9 13.5 15.5 21.8 13.5 28.8 19.6 19.2 26.2 23.6 1986 ..................................................................................... 25.9 26.2 25.1 19.2 10.6 14.9 19.0 23.8 19.3 21.7 23.9 20.0 10.6 26.2 20.8 10.6 27.0 19.6 1987 ..................................................................................... 23.6 27.0 16.6 10.6 15.3 18.0 18.3 18.2 16.3 13.0 12.9 21.0 10.6 27.0 17.6 183 261 212 1988 ..................................................................................... 21.3 26.1 19.4 18.3 18.6 19.1 19.1 18.0 13.7 10.7 11.2 18.3 10.7 26.1 17.8 15.8 22.5 18.4 1989 ..................................................................................... 19.1 22.5 16.2 15.8 20.7 22.4 22.4 21.8 12.9 11.0 19.0 19.9 11.0 22.5 18.6 15.1 24.2 19.3 1990 ..................................................................................... 24.2 19.4 15.1 17.7 19.2 20.2 19.7 18.2 11.0 10.0 11.5 17.3 10.0 24.2 17.0 12.5 21.1 17.8 1991 ..................................................................................... 20.6 21.1 12.5 17.4 19.4 19.2 19.3 19.3 13.8 13.2 14.2 18.9 12.5 21.1 17.4 12.6 22.3 18.1 1992 ..................................................................................... 22.3 20.4 12.6 16.4 19.3 19.4 19.2 18.1 13.6 10.0 10.1 18.2 10.0 22.3 16.6 10.3 18.8 14.3 1993 ..................................................................................... 18.8 13.8 10.4 10.3 15.2 15.7 14.8 15.8 11.3 9.9 11.0 13.6 9.9 18.8 13.4 11.7 14.3 13.0 1994 ..................................................................................... 14.3 13.5 12.0 11.7 23.3 22.2 19.0 18.4 15.7 11.4 13.6 18.5 11.4 23.3 16.1 12.3 20.9 17.2 1995 ..................................................................................... 20.9 20.2 14.1 12.3 12.6 11.1 13.2 29.8 37.0 35.9 31.1 20.2 11.1 37.0 21.5 18.4 28.2 22.2 1996 ..................................................................................... 22.9 21.1 18.4 28.2 36.5 35.4 36.7 36.1 35.1 26.3 20.7 19.0 18.4 36.7 28.0 16.0 22.9 19.0 1997 ..................................................................................... 22.9 21.1 16.0 16.2 31.1 42.5 57.3 49.9 46.5 49.4 42.3 21.9 16.0 57.3 34.8 19.3 24.6 21.4 1998 ..................................................................................... 22.0 24.6 19.3 19.4 24.2 25.7 24.0 24.0 21.2 17.1 20.5 20.9 17.1 25.7 21.9 20.9 27.1 24.6 1999 ..................................................................................... 24.7 26.7 23.7 27.1 26.2 29.7 28.6 27.9 23.4 18.8 17.5 19.6 17.5 29.7 24.5 18.3 24.1 20.5 2000 ..................................................................................... 20.8 24.1 18.3 19.5 22.3 24.3 23.5 23.1 18.0 14.2 20.9 18.1 14.2 24.3 20.6 12.5 18.8 15.8 2001 ..................................................................................... 18.8 16.9 12.9 12.5 12.3 13.8 13.8 14.0 11.4 10.2 10.6 12.9 10.2 18.8 13.3 10.8 13.2 12.5 2002 ..................................................................................... 13.1 13.2 12.5 10.8 12.8 20.9 20.8 21.1 17.5 13.8 18.0 19.6 10.8 21.1 16.2 17.3 22.3 19.2 2003 ..................................................................................... 18.4 22.3 17.3 18.6 18.7 21.3 21.4 21.1 16.9 10.8 11.7 15.9 10.8 22.3 17.9 15.9 23.1 18.4 2004 ..................................................................................... 19.2 23.1 16.7 16.9 15.8 18.0 17.9 17.2 15.0 11.5 12.7 15.2 11.5 23.1 16.6 12.1 17.4 14.6 2005 ..................................................................................... 15.4 13.0 12.1 17.4 16.5 15.0 15.2 15.5 14.1 12.6 13.4 15.4 12.1 17.4 14.6 13.8 17.8 15.4 2006 ..................................................................................... 17.8 15.5 14.5 13.8 15.3 19.8 20.6 22.0 18.1 12.1 13.1 15.3 12.1 22.0 16.5 13.5 15.9 15.1 2007 ..................................................................................... 15.9 15.8 14.8 13.5 13.3 16.0 15.9 16.0 11.6 10.8 10.8 14.9 10.8 16.0 14.1 12.5 15.3 14.1 2008 ..................................................................................... 15.0 15.3 12.8 12.5 12.9 14.3 13.6 13.9 12.6 ............ ............ ............ ............ ............ ............ ............ ............ ............

STATISTICS (JANUARY 1968 TO DECEMBER 2007) 

NUM ...................................................................................... 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 40 
164 

TABLE 3–2.—AVERAGE DAILY OUTFLOW FOR THE MONTH FROM LAKE SAKAKAWEA, JUNE 1967 TO SEPTEMBER 2008 (IN 1,000 cfs)—Continued 

[Retrieved on 8-October-2008] 

YEAR 

MONTH FULL YEAR (Jan–Dec) Colder Months (Dec–Apr) 1

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC MIN MAX MEAN MIN MAX MEAN 

MIN ....................................................................................... 13.1 13.0 10.4 10.3 10.6 11.1 13.2 14.0 11.0 9.9 10.1 12.9 9.9 16.0 13.3 10.3 13.2 12.5 MEAN .................................................................................... 23.0 24.2 19.6 19.2 21.2 23.0 24.4 24.0 20.5 18.8 19.8 20.3 14.5 29.1 21.5 17.0 25.1 21.0 MAX ...................................................................................... 30.5 33.7 30.6 37.5 38.5 42.5 61.8 54.1 46.5 49.4 42.3 29.5 23.8 61.8 34.8 26.0 37.5 29.2 STDEV ................................................................................... 4.5 5.7 5.6 6.3 7.7 8.1 10.3 8.5 7.9 8.9 7.7 3.6 3.8 9.3 5.4 4.1 5.7 4.6 

1 Rows include Jan to Apr of following year. 
165 

FIGURE 3–7.—Annual total outflow from Lake Sakakawea at Garrison Dam from 

1968 to 2007 (Source of data: USACE). 

FIGURE 3–8.—Daily Discharge in the Missouri River at Bismarck from 1958 to 2008 

(Source of data: USGS). 
166 

FIGURE 3–9.—Annual mean discharge at Bismarck from 1958 to 2007 (Source of 

data: USGS). 
167 

TABLE 3–3.—MONTHLY MEAN FLOW AT BISMARCK 

[USGS Gaging Station 06342500] 

Year 

Month 

Mean 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

1958 .................................................................................................................. 14,190 13,270 15,370 19,090 20,770 29,370 14,730 17,680 29,710 20,430 16,750 14,970 18,861 1959 .................................................................................................................. 14,580 15,990 16,150 16,800 21,000 21,340 20,950 21,680 21,220 16,200 15,590 14,970 18,039 1960 .................................................................................................................. 15,110 18,360 19,600 14,190 13,260 8,445 10,840 12,760 12,560 10,000 12,330 15,120 13,548 1961 .................................................................................................................. 20,620 20,090 20,880 20,790 19,340 14,350 13,760 16,590 9,369 16,410 25,180 16,080 17,788 1962 .................................................................................................................. 21,710 23,540 24,080 23,540 22,310 22,140 13,800 9,271 8,121 8,399 8,155 14,330 16,616 1963 .................................................................................................................. 20,270 20,200 22,440 17,000 9,234 16,720 17,140 9,821 9,683 11,600 17,010 24,590 16,309 1964 .................................................................................................................. 24,320 28,000 25,850 20,550 17,780 21,390 14,590 13,600 18,920 17,150 23,770 21,780 20,642 1965 .................................................................................................................. 28,230 31,430 31,390 29,090 23,870 27,630 22,610 14,490 13,140 29,460 33,950 31,260 26,379 1966 .................................................................................................................. 20,680 27,810 25,760 10,510 10,900 13,350 18,700 20,230 17,440 21,090 25,600 23,060 19,594 1967 .................................................................................................................. 27,020 32,610 31,710 19,220 10,900 27,130 32,920 39,400 28,760 32,390 28,900 27,350 28,193 1968 .................................................................................................................. 27,690 33,310 23,700 23,570 21,500 18,570 17,950 22,380 24,910 35,080 26,360 28,270 25,274 1969 .................................................................................................................. 32,350 34,840 33,550 32,350 26,060 19,930 29,740 33,300 28,880 26,860 28,520 31,690 29,839 1970 .................................................................................................................. 26,980 29,840 22,530 28,020 31,950 31,050 28,720 29,920 24,170 28,730 31,060 27,310 28,357 1971 .................................................................................................................. 28,300 29,850 32,760 38,220 40,950 37,360 36,910 28,910 26,260 26,450 27,240 24,150 31,447 1972 .................................................................................................................. 31,220 30,500 34,370 40,370 42,030 40,800 30,130 26,230 22,650 22,970 24,910 21,220 30,617 1973 .................................................................................................................. 28,190 27,220 27,860 22,660 18,000 19,690 21,450 21,910 20,930 20,340 21,110 23,970 22,778 1974 .................................................................................................................. 27,500 28,740 28,360 21,850 23,030 25,680 28,060 29,780 25,920 29,480 26,400 25,920 26,727 1975 .................................................................................................................. 24,470 30,180 27,350 22,650 35,450 43,540 64,610 57,010 39,700 34,210 34,390 29,100 36,888 1976 .................................................................................................................. 28,060 34,640 29,570 34,700 38,030 40,880 39,680 34,990 29,410 28,370 32,460 26,500 33,108 1977 .................................................................................................................. 29,100 30,700 23,580 17,950 17,200 17,250 18,850 17,790 16,230 14,050 17,190 22,980 20,239 1978 .................................................................................................................. 27,770 30,710 26,070 23,060 17,550 33,030 42,410 42,260 35,460 34,550 35,040 24,710 31,052 1979 .................................................................................................................. 31,730 32,550 29,180 33,950 40,120 40,370 28,940 22,870 18,850 16,650 15,250 20,570 27,586 1980 .................................................................................................................. 23,310 29,790 28,630 22,090 19,630 22,380 27,520 25,350 23,610 23,750 25,620 22,270 24,496 1981 .................................................................................................................. 26,150 29,700 25,170 17,630 19,330 27,490 30,350 25,120 20,430 16,940 16,130 20,320 22,897 1982 .................................................................................................................. 27,850 34,790 31,130 24,830 26,560 26,310 27,580 22,490 19,810 20,750 31,480 26,120 26,642 1983 .................................................................................................................. 21,210 31,640 32,790 24,010 18,790 19,660 19,790 27,470 25,090 16,230 18,490 22,480 23,138 1984 .................................................................................................................. 28,430 28,810 22,950 18,290 16,030 16,650 23,350 29,010 27,760 25,860 27,690 23,380 24,018 1985 .................................................................................................................. 27,980 31,490 22,230 20,660 21,320 23,160 22,030 20,810 19,340 14,340 15,850 22,870 21,840 1986 .................................................................................................................. 27,710 28,610 31,730 22,470 12,840 15,640 20,940 26,290 21,610 23,250 26,340 22,020 23,288 1987 .................................................................................................................. 25,720 29,530 20,590 12,580 16,510 19,940 20,820 20,930 18,290 14,910 14,490 23,040 19,779 1988 .................................................................................................................. 23,930 31,280 24,380 21,140 20,520 21,040 21,210 19,780 15,050 11,110 11,170 20,400 20,084 1989 .................................................................................................................. 20,190 24,540 17,370 17,020 22,550 24,870 24,820 24,400 14,640 11,630 20,150 21,210 20,283 1990 .................................................................................................................. 26,020 21,930 17,820 19,010 20,520 22,150 21,720 19,720 12,680 11,000 12,070 18,590 18,603 
168 

TABLE 3–3.—MONTHLY MEAN FLOW AT BISMARCK—Continued 

[USGS Gaging Station 06342500] 

Year 

Month 

Mean 

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

1991 .................................................................................................................. 21,900 22,290 14,570 18,370 21,480 21,560 21,610 21,840 15,500 14,170 14,810 19,450 18,963 1992 .................................................................................................................. 23,050 21,160 14,240 17,180 20,910 20,620 20,730 19,410 14,700 10,970 10,930 18,650 17,713 1993 .................................................................................................................. 19,330 14,270 10,670 10,420 15,930 17,020 19,270 17,650 12,900 11,040 11,520 13,590 14,468 1994 .................................................................................................................. 14,160 13,640 13,490 12,520 25,520 25,400 20,870 19,920 17,160 13,690 14,590 20,810 17,648 1995 .................................................................................................................. 23,080 24,250 17,780 13,130 13,840 11,660 13,580 32,180 42,670 40,150 34,980 21,710 24,084 1996 .................................................................................................................. 24,440 23,620 20,730 31,350 38,960 38,470 39,500 39,320 38,060 28,510 22,470 20,260 30,474 1997 .................................................................................................................. 24,340 22,660 21,700 18,380 32,310 42,580 56,770 48,100 45,060 48,180 43,240 23,550 35,573 1998 .................................................................................................................. 23,490 26,230 20,750 19,270 23,530 25,890 24,490 24,640 21,430 15,640 19,870 21,610 22,237 1999 .................................................................................................................. 24,570 26,690 26,610 27,080 26,480 29,930 28,830 28,500 24,660 20,240 17,970 20,420 25,165 2000 .................................................................................................................. 22,090 25,910 19,950 19,940 22,190 25,470 24,940 24,660 19,400 14,690 20,880 18,740 21,572 2001 .................................................................................................................. 19,480 17,740 16,060 14,090 12,430 14,550 14,190 14,130 11,290 10,160 10,510 13,250 13,990 2002 .................................................................................................................. 13,360 13,530 13,030 11,800 12,630 22,030 21,780 22,260 18,820 14,240 18,370 21,020 16,906 2003 .................................................................................................................. 19,280 23,560 18,710 19,210 19,490 22,810 22,660 21,850 17,160 10,770 11,460 15,960 18,577 2004 .................................................................................................................. 19,950 24,610 19,180 17,590 15,450 18,440 18,090 17,230 15,060 11,590 12,580 15,600 17,114 2005 .................................................................................................................. 16,000 13,540 12,870 17,850 17,430 16,160 16,220 16,140 14,810 13,070 13,680 16,060 15,319 2006 .................................................................................................................. 18,690 16,100 15,130 13,920 15,130 20,280 21,350 22,970 20,080 12,830 13,470 15,780 17,144 2007 .................................................................................................................. 16,470 16,430 15,990 14,090 13,270 16,770 16,300 16,670 12,840 11,410 ............ ............ 15,024 Mean 1958–2007 .............................................................................................. 23,445 25,454 22,767 20,921 21,656 23,979 24,576 24,234 21,244 19,840 21,183 21,409 22,538 Mean 1968–2007 .............................................................................................. 24,139 26,036 22,628 21,382 22,836 24,927 26,219 25,905 22,332 20,222 21,301 21,681 23,274 
169 

FIGURE 3–10.—Monthly mean discharge rates at Bismarck during the five colder 

months (December to April) from 1968 to 2007 (Source of data: USGS). 
170 

FIGURE 3–11.—Monthly outflow at Garrison Dam vs. monthly discharge at Bismarck 

(1968 to 2007) (Sources of data: USACE, USGS). 
171 

FIGURE 3–12.—Monthly outflow at Garrison Dam and monthly discharge at Bismarck (1967 to 2008). Higher discharges at Bismarck reflect the added runoff from 

the watershed downstream of Garrison Dam (Sources of data: USACE, USGS). 

FIGURE 3–13.—Residual discharge after subtracting outflow at Garrison Dam from 

the discharge at Bismarck, reflecting the runoff from the watershed between Garrison Dam and Bismarck (1967 to 2007) (Sources of data: USACE, USGS). 
172 

FIGURE 3–14.—Percent flow at Bismarck relative to the outflow at Garrison Dam for 

different periods of the year (1967 to 2007). Highest additional discharge occurred 

during the spring melting season. (Sources of data: USACE, USGS). 

FIGURE 3–15.—Monthly releases at Garrison Dam, relative to total annual releases, 

showing that highest releases occur during the peak demand periods in December, 

July, and August (Sources of data: USACE). 
173 

FIGURE 3–16.—Stage-discharge relationship in Bismarck, reflecting an increase of 

the stage at high flows (USACE, 2004c). 

3.3.3. Hydropower Generation 

Water release rates at Garrison Dam for ice-in vary from year to year depending 

on the specific conditions and needs of other uses. Under ‘‘normal conditions’’, the 

USACE would release from ‘‘the top of the maintenance zone’’ and gradually release 

the water over the winter. However, reduced runoff in the watershed has resulted 

in a decline in power generation between 1967 and 2008 by almost a factor of 2 (Figure 2–10). Using linear regression, the decline was approximately 8 percent greater 

during the 5-month-long colder period (December to April) than during the other 

months of the year (Figure 3–18). Specifically, the greatest decline in the colder period occurred during January–February and ice-out (March–April) (Figure 3–19). 

TABLE 3–4.—CHANNEL CHANGES DOWNSTREAM OF GARRISON DAM BETWEEN 1958 AND 1985 

(USACE, 1993c). 

[QUALITATIVE ACTIVE CHANNEL CHANGES 1958 TO 1985 FOR A DISCHARGE OF 20,000 CFS] 

1960 R.M. THALWEG 

ELEV 

AVE. BED 

ELEV 

AVE 

DEPTH WIDTH AREA 

D50 

GRAIN 

SIZE 

1388.19 .......................................................................... - - - ∂ - ∂ 

1387.09 .......................................................................... - - ∂ - - ∂ 

1385.88 .......................................................................... - - - ∂ - ∂ 

1384.86 .......................................................................... - - - - - ∂ 

1383.33 .......................................................................... - - ∂ - - ∂ 

1382.25 .......................................................................... - - * - - - 

1381.34 .......................................................................... - - - - - ∂ 

1380.43 .......................................................................... - - ∂ - - ∂ 

1379.68 .......................................................................... - - - ∂ - ∂ 

1379.00 .......................................................................... - - - ∂ - ∂ 

1378.42 .......................................................................... - - * * - ∂ 

377.53 ............................................................................ * - - ∂ - ∂ 

1376.71 .......................................................................... - - - - ∂ ∂ 

375.89 ............................................................................ - - - - - ∂ 

374.91 ............................................................................ - - - - - ∂ 

1374.58 .......................................................................... - - * - - ∂ 

1373.80 .......................................................................... ∂ - ∂ ∂ ∂ ∂ 

1372.50 .......................................................................... - - ∂ * ∂ ∂ 

1371.37 .......................................................................... - - - - - ∂ 

1370.29 .......................................................................... ∂ - * * - ∂ 

1368.89 .......................................................................... * - - ∂ ∂ ∂ 
174 

TABLE 3–4.—CHANNEL CHANGES DOWNSTREAM OF GARRISON DAM BETWEEN 1958 AND 1985 

(USACE, 1993c).—Continued 

[QUALITATIVE ACTIVE CHANNEL CHANGES 1958 TO 1985 FOR A DISCHARGE OF 20,000 CFS] 

1960 R.M. THALWEG 

ELEV 

AVE. BED 

ELEV 

AVE 

DEPTH WIDTH AREA 

D50 

GRAIN 

SIZE 

1367.40 .......................................................................... - - - - - ∂ 

1366.24 .......................................................................... - - ∂ - - ∂ 

1364.87 .......................................................................... ∂ - ∂ - - ∂ 

1363.86 .......................................................................... ∂ - - - - ∂ 

1362.55 .......................................................................... ∂ - - ∂ - - 

1360.40 .......................................................................... - - ∂ - - - 

1358.50 .......................................................................... * - - ∂ ∂ ∂ 

1356.50 .......................................................................... * - ∂ ∂ ∂ ∂ 

1353.85 .......................................................................... ∂ - - - - ∂ 

1351.83 .......................................................................... ∂ - - * * ∂ 

1349.46 .......................................................................... - - - ∂ ∂ ∂ 

1346.46 .......................................................................... - - ∂ ∂ ∂ - 

1344.72 .......................................................................... - - ∂ - - - 

1343.30 .......................................................................... - - - ∂ - - 

1341.40 .......................................................................... ∂ - - ∂ ∂ ∂ 

1339.67 .......................................................................... - - * ∂ ∂ - 

1338.05 .......................................................................... - - ∂ ∂ ∂ ∂ 

1336.82 .......................................................................... - - - ∂ ∂ - 

1335.91 .......................................................................... - - * - ∂ ∂ 

* NO CHANGE OR INCOMPLETE DATA. 

- MEASURED UNITS HAVE DECREASED FOR THAT PARAMETER OR MSL ELEVATION HAS DECREASED. 

∂MEASURED UNITS HAVE INCREASED FOR THAT PARAMETER OR MSL ELEVATION HAS INCREASED. 
175 

FIGURE 3–17.—Tailwater elevation changes at Garrison Dam at different flows, reflecting the degradation of the channel since the construction of the dam (USACE, 

2004c). 

FIGURE 3–18.—Monthly gross energy generation in colder and warmer periods, showing a slightly greater decrease during colder months over time compared to warmer 

months (Source of data: USACE). 
176 

FIGURE 3–19.—Monthly gross energy generation in colder and warmer periods, with 

higher resolution during colder months (Source of data: USACE). 

Power generation during the colder period accounted for 58 percent of the total 

annual power generation; this value has decreased to 53 percent (Figure 3–20). Although there are other potential causes for a relatively greater decline during the 

winter months (such as the statistical effect of the floods in the mid-1990s), the decline could have been caused by aggradation in the Missouri River in the headwater 

of Lake Oahe. 

Siltation in the river has resulted in aggradation and widening of the river channel south of Bismarck. In urban areas such as Bismarck and Mandan the river 

channel cannot widen without an increased risk of flooding and the loss of property. 

As a result, the flow release rates have been reduced over time to prevent flooding. 

This effect is expected to continue. The risk is higher during wet years when the 

elevation of Lake Oahe is higher, and consequently its headwaters extend further 

north, and thus more sediments is being deposited again closer to the urban areas 

of Bismarck and Mandan than at the present time. It is likely that power generation in winter during wet years will decrease as a result. However, high inflows to 

the reservoir during wet years may require higher water release rates even during 

the colder months. This condition occurred during the wet years between 1995 and 

2000 when release rates (and thus energy generation) during colder months were 

approximately 50 percent higher than during subsequent years (i.e., from year 2001 

to the present) (Figure 3–18). 

One of the biggest impacts to hydropower generation from ice dams is the reduction in flexibility of hydropower generation in winter (if the risk for flooding is to 

be reduced). Specifically, as stated above, the power plant cannot be operated as an 

optimally efficient peaking facility. 

Prevention of flooding means that the water from Lake Sakakawea is released at 

a different time of the year, generating power at that time. Since rates applied to 

power generated at the Garrison Dam do not vary on a month-by-month basis, annual revenues from power generation are thus not lost. The total annual revenue 

from energy generation would only be adversely affected if water is released from 

Lake Sakakawea during warmer months in excess of the maximum generating capacity of Garrison Dam (41,000 cfs), in order to prepare for reduced releases during 

the colder months. 

However, winter is one of the peak power demand periods. Thus, reduced power 

generation capacity in winter at the Garrison Dam power plant may mean that 

power from other, potentially more expensive sources needs to be generated to accommodate demand. 
177 

FIGURE 3–20.—Power generation during colder months (5-month period) relative to 

total annual generation (Source of data: USACE). 

4.0 RECOMMENDATIONS 

Releases from Garrison Dam by the USACE for various uses already aim to minimize flooding. Detailed monitoring data should continue to be collected to allow for 

effective adaptive management measures of the operations of Garrison Dam to 

maximize the benefit of the dam and the overall System, while minimizing impacts. 

This is particularly important in light of the fact that there are a number of natural 

variables that change regularly (daily, as well as longterm), such as rainfall, temperature, flow, erosion and deposition patterns, etc. In addition, the river serves 

multiple uses that also need to be balanced, e.g., navigation, flood protection, irrigation, recreation, etc. Specifically in winter, flood protection from ice dams is a more 

important driver for the determination of the release rates. 

Dredging could be considered on a temporary and localized basis for flood control, 

but a larger-scale dredging operation would most likely be cost-prohibitive. Dredging 

has been conducted for selected water intakes which are affected by sedimentation 

(such as the power plant Leland Olds in Stanton). Small-scale dredging for similar 

purposes is probably cost-effective. 

The risk of flooding will increase once the current drought has passed, and Lake 

Oahe again has full pool elevations. Higher pool elevations imply that sediment carried by the Missouri River will be settling out closer to the city of Bismarck than 

at present which will result in further aggradation. A higher risk of flooding requires further reduction in hydropower generation at Garrison Dam. The existing 

flood plain and zoning should be reviewed in the cities of Bismarck and Mandan 

to determine if additional steps should be undertaken to better accommodate high 

flows in the Missouri River. Supposedly, there has been additional development 

down close to the river edge around the city. Such developments should be avoided, 

or potentially even reversed if feasible. Similarly, the flood plain and zoning in other 

potentially affected areas (i.e., non-urban areas) should be reviewed. Further, appropriate bank stabilization measures should be considered in areas most heavily affected by flooding. After all, when reservoir levels are high during wetter years, 

more water needs to be passed through the river, which will limit the reduction in 

flow that can be achieved in the winter (as occurred during the wet period from 

1995 to 2000; Figure 3–18). 

As suggested by the Water Commission in their comments to the draft report, it 

is recommended to conduct a study that more quantitatively demonstrates that 

higher elevations in Lake Oahe will result in a decrease in flow velocities due to 

aggradation. This study would need to address the range of variables that affect the 

flow in order to extract the impact of lake elevations on outflow rates. A first-order 

assessment was conducted during this study, comparing average outflow rates at 

Garrison Dam with elevation in Lake Oahe, although the available data were insufficient to quantitatively address the range of variables. The recommended assessment should include an estimate of future trends of sedimentation and resulting impacts. 
178 

5.0 REFERENCES 

Berger (Louis Berger Group, Inc.), 2008, Identification and sources and deposits 

and locations of erosion and sedimentation. Prepared for the U.S. Army Corps of Engineers Omaha District and the Missouri River Joint Water Board (August 2008). 

Biedenharn, S.S., R.S. Soileau, L.C. Hubbard, P.H. Hoffman, C.R. Thorne, and 

C.C. Bromley, 2001, Missouri River-Fort Peck Dam to Ponca State Park 

Geomorphological Assessment related to Bank Stabilization. 

FEMA, (Federal Emergency Management Agency), 2005, Flood Insurance Study, 

Burleigh County, North Dakota, and incorporated areas. 

Geiger, A.F., 1963, Developing sediment storage requirements for upstream retarding reservoirs. Proc. Federal Interagency Sedimentation Conf., USDA–ARS 

Misc. Pub. 970, p. 881–885. Cited in: Morris, G.L. and J. Fan, 1997, Reservoir Sedimentation Handbook. 

NDGFD (North Dakota Game and Fish Department), 2002, The Missouri and Yellowstone Rivers in North Dakota, Williston Reach)—A Report to the Director. http:// 

gf.nd.gov/multimedia/news/positions/mo-riv-whitepaper-williston.html. 

Remus, J., P.E., 2008, Sedimentation in the Upper Missouri River Basin. U.S. 

Army Corps of Engineers. http://watercenter.unl.edu/MoRiverMainstem/Sedimentation.asp. Accessed November 13, 2008. 

USACE (U.S. Army Corps of Engineers), 1978, Buford Trenton Irrigation District: 

Backwater and drainage problems. USACE Omaha District, Omaha Nebraska, Design Memorandum MGR146. 

USACE (ll), 1992, Williston area studies. Aggradation analysis. USACE Omaha 

District, Nebraska, Draft report. 

USACE (ll), 1993a, Aggradation, Degradation, and Water Quality Conditions: 

Missouri River Mainstem Reservoir System. USACE Omaha District. 

USACE (ll), 1993b, Lake Oahe aggradation study. USACE Omaha District, 

M.R.D. Sediment Memoranda, No. 15. 

USACE (ll), 1993c. Downstream Channel and Sediment Trends Study. USACE 

Omaha District. 

USACE (ll), 1999, Missouri River Main Stem Reservoirs Hydrologic Statistics. 

RCC Technical Report F–99. USACE Missouri River Region Resevoir Control Center. 

USACE (ll), 2000a, Downstream Channel and Sediment Trend Study Update. 

Garrison Project—North Dakota. Prepared by Sedimentation and Channel Stabilization Section, Hydrologic Engineering Branch (M.R.D. Sediment Memoranda, No. 1 

6A). 

USACE (ll), 2004a, Missouri River Final Environmental Impact Statement, 

Master Water Control Manual Review and Update. 

USACE (ll), 2004b, Record of Decision, Master Water Control Manual Review 

and Update. 

USACE (ll), 2004c, Missouri River stage trends. RCC Technical Report A–04. 

Prepared by Reservoir Control Center, USACE Northwestern Division—Missouri 

River basin, Omaha, Nebraska. 

USACE (ll), 2006, Missouri River Mainstem Reservoir System, Master Water 

Control Manual, Missouri River Basin. Reservoir Control Center, USACE Northwestern Division—Missouri River Basin. 

USGS (United States Geological Survey), 1995, Transport and sources of sediment 

in the Missouri River between Garrison Dam and the headwaters of Lake Oahe, 

North Dakota, May 1988 through April 1991. USGS Water-Resources Investigations 

Report 95–4087. Prepared in cooperation with the USACE. 

USGS (ll), 2008, Flow data at the Bismarck gaging station. Accessed on Nov. 

8, 2008. http://waterdata.usgs.gov/nwis/nwisman/ 

?sitelno=06342500&agencylcd=USGS. 

Williams, G.P. and M.G. Wolman, 1984, Downstream effects of dams on alluvial 

rivers. U.S. Geological Survey Professional Paper 1286, 83p. 

Wuebben, J.L. and J.J. Gagnon, 1995, Ice jam flooding on the Missouri River near 

Williston, North Dakota. Accessed at: http://www.tpub.com/content/ArmyCRREL/ 

CR95l19/CR95l190007.htm. 

PERSONAL COMMUNICATION 

Larry Cieslik, Chief, Reservoir Control Center, U.S. Army Corps of Engineers; November 6, 2008. 

Bruce Engelhardt, Investigations Section Chief, North Dakota State Water Commission; November 11, 2008. 

Jody Farhat, P.E., Power Production Team Leader, Missouri River Basin Water, 

Management Division, Northwestern Division, U.S. Army Corps of Engineers, 

Omaha, NE; November 10, 2008. 
179 

James Mueller, Chief, Maintenance Engineering Section, U.S. Army Corps of Engineers; January 8, 2009. 

Bill Mulligan, Chief, Civil Works Project Management, U.S. Army Corps of Engineers, Omaha, NE; November 17, 2008. 

John Remus, Chief, Hydrologic Engineering Branch, U.S. Army Corps of Engineers, Omaha, NE; November 7, 2008. 

Ronald Sando, Water Resources Consultant, Missouri River Joint Water Board; 

October 24, 2008. 

John Stonebarger, UGP Energy Marketing Supervisor, Western Area Power Administration, November 10, 2008. 

U.S. Geological Survey, North Dakota Water Science Center, Bismarck, ND; November 12, 2008. 

Peter Whiting, Associate Dean of the College of Arts and Sciences, and Associate 

Professor of Geological Sciences, Case Western Reserve University, Cleveland, OH; 

October 23, 2008. 

Acknowledgment 

We greatly appreciate the time and effort of the persons listed above to provide 

helpful documentation and information for this project. 

EXHIBIT 1—COMBINED RESERVOIR REGULATION AND POWER PRODUCTION

ORDER NO. ST–2, 1983 

Garrison Standing Order 

To: Garrison Office Attn: Project Engineer 

From: Reservoir Control Center 

Re: Garrison Combined Reservoir Regulation and Power Production Order No. 

St–2, 1983. This order will apply when referenced in the Daily Reservoir 

Regulation and Power Production Orders. 

1. Minimum energy generation shall be maintained to avoid low pumping 

stages below Garrison as follows: 

Period Minimum Energy for Period 

4 hours 300 MWh 

5 hours 400 MWh 

6 hours 550 MWh 

7 hours 700 MWh 8 hours 850 MWh 

The WAPA power systems dispatcher shall be advised whenever it appears 

that loading is falling below the above minimums so that plant loading can be 

increased. The above minimums have been furnished to WAPA. 

2. Unless otherwise specified in daily reservoir regulation and power production orders supplementary releases will be made only as necessary to maintain 

daily average discharge of 6,000 cfs. The WAPA dispatcher will be notified as 

far in advance as possible of the intent to make supplementary releases. 

APPENDIX E—IMPACT OF SILATION OF THE MISSOURI RIVER ON FISH AND WILDLIFE IN

NORTH DAKOTA

1.0 INTRODUCTION 

The contemporary Missouri River in North Dakota is highly modified from its natural character due to the Flood Control Act of 1944. The Flood Control Act was Federal legislation that led to the establishment of the Pick-Sloan Plan to construct six 

large dams on the Missouri River mainstem from Nebraska to Montana. 

The completion of the Pick-Sloan Plan has had several implications for the ecology 

of the river. The creation of reservoirs has converted riverine to lacustrine habitat 

(NRC, 2002; Galat et al., 2005) by stabilizing river flows (Hesse and Mestl, 1993; 

Galat and Lipkin, 2000). The stabilization of flows and the presence of dams cause 

sediment to become trapped in the reservoirs, resulting in a sediment deficit downstream (Macek-Rowland, 2000; Galat et al., 2005). Reservoirs also reduce channel 

meandering, resulting in a decline in off-channel habitat (Shields et al., 2000). 

North Dakota contains one dam, Garrison Dam, and its associated reservoir, Lake 

Sakakawea. The reservoir known as Lake Oahe, formed by the Oahe Dam in South 

Dakota, also extends into North Dakota from the south. Therefore, from an ecological perspective, the Missouri River in North Dakota may be thought of as having 

four parts: 

—The Williston Reach.—The riverine segment close to the Montana border, into 

which the Yellowstone River flows and which flows into Lake Sakakawea; 
180 

1 ‘‘Level I species are those having a high level of conservation priority because of declining 

status in North Dakota or across their range; or have a high rate of occurrence in North Dakota, 

constituting the core of the species breeding range, but may be at-risk range-wide. Level II species are those having a moderate level of conservation priority; or a high level of conservation 

priority but a substantial level of non-[State wildlife grant] funding is available to them. Level 

III species are those having a moderate level of conservation priority but are believed to be peripheral or non-breeding in North Dakota’’ (Hagen et al., 2005, p.10). 

—Lake Sakakawea.—The reservoir formed by Garrison Dam (closed in 1953), 

whose entire range is within the state of North Dakota; 

—The Garrison Reach.—The riverine segment from Garrison Dam to the headwaters of Lake Oahe; and 

—Lake Oahe.—The reservoir formed by Oahe Dam in South Dakota (closed in 

1958) and which is in both North Dakota and South Dakota. 

2.0 DESCRIPTION OF THE RESOURCE 

The creation of these reservoirs has resulted in a suite of ecological changes, including the creation of major warm water sport fisheries. It has also resulted in declines for many of the native fish that were adapted to the pre-impoundment conditions. Therefore, in this section, we will define the ‘‘resource’’ as two groups of animals: those that constitute a conservation concern and those that are important for 

recreational purposes (hunting and fishing). These are hereafter referred to as ‘‘Conservation Species’’ and ‘‘Recreational Species,’’ respectively. 

2.1 Conservation Species 

Within the first group, we include those animals that are listed as species of conservation priority in the North Dakota Wildlife Action Plan (NDWAP) of 2005. The 

NDWAP report uses a ‘‘conservation priority’’ system that rates a species at a particular ‘‘level’’ of conservation priority.1 The report then divides the State of ND into 

geographic focus areas. Our intent is to include in the ‘‘conservation species’’ group 

all those species of conservation priority that are listed in the NDWAP’s ‘‘Missouri 

River and Breaks’’ section, which lists all of the animals of conservation priority 

that fall within the Missouri River focus area in the State of ND. The section can 

be found on page 71 of the NDWAP report. 

We do not include the species of conservation priority that are not listed in the 

‘‘Missouri River and Breaks’’ geographic focus area as per the NDWAP report of 

2005. Such animals have ranges that fall outside of the Missouri River mainstem 

system. 

The species listed under the ‘‘Missouri River and Breaks’’ geographic focus area 

of the NDWAP are: 

—Birds.—Bald eagle (Haliaeetus leucocephalus), piping plover (Charadrius 

melodius), least tern (Sterna antillarum), red-headed woodpecker (Melanerpes 

erythrocephalus), golden eagle (Aquila chyrsaetos) 

—Mammals.—River otter (Lotra Canadensis) 

—Reptiles and Amphibians.—Smooth softshell turtle (Apalone mutica), false map 

turtle (Graptemys pseudogeographica) 

—Fish.—Sturgeon chub (Macrhybopsis gelida), pearl dace (Margariscus margarita), blue sucker (Cycleptus elongatus), paddlefish (Polydon sp athula), pallid 

sturgeon (Scaphirhynchus albus), flathead catfish (Pylodictis olivaris), flathead 

chub (Platygobio gracilis), sicklefin chub (Macrhybopsis meeki), yellow bullhead 

(Ameiurus natalis) 

The pallid sturgeon, in addition to being listed as a species of conservation priority, is also a federally endangered species. The piping plover and the least tern 

are also federally threatened species. 

While the NDWAP report lists the pearl dace (Margariscus margarita) and the 

yellow bullhead (Ameiurus natalis) in the ‘‘Missouri River and Breaks’’ section, we 

do not include the yellow bullhead and the pearl dace in our analysis. These fish 

either do not use the Missouri River mainstem, or only very rarely make use of it, 

and so they fall outside the scope of this report. 

2.2 Recreational Species 

The recreational species group includes the most popular game fish as described 

in the creel surveys prepared for the year 2006 by NDGF (Brooks et al., 2007a, 

2007b). According to these surveys, the most popular sport fish in Lake Sakakawea, 

by estimated number of fish caught during 2006, in order of popularity, are: walleye, 

sauger, northern pike, Chinook salmon, white bass, and channel catfish. The order 

from most popular to least popular in Lake Oahe is walleye, channel catfish, sauger, 

northern pike, white bass, and Chinook salmon. Full details, including the estimates 
181 

2Steve Dyke, a conservation biologist for NDGF suggested we consider the Canada goose as 

part of this assessment. 

and the methods used to accomplish these estimates, are available in Brooks et al 

(2007a, 2007b). 

The recreational species group also includes a bird species that is important for 

recreational hunting on the Missouri River: the Canada goose (Branta Canadensis).2

The Canada goose is a game species, and over 100,000 of them are shot in the State 

of North Dakota every year (Richkus et al., 2008), a significant proportion of which 

are shot on the Missouri River mainstem and floodplain. We also include beavers 

and muskrats, as hunting and trapping occurs for these animals on the Missouri 

River (Fred Ryckman, 2008, personal communication). White-tailed deer is another 

game species that is hunted on the Missouri River floodplain. However, the species 

is not evaluated here because neither the literature nor the interviews indicated 

that siltation has any effect on white-tailed deer. 

3.0 AREAS WHERE THE RESOURCE COULD BE IMPACTED BY SEDIMENTATION 

In this section we summarize sediment dynamics in the Missouri River in North 

Dakota for each of the four river sections defined in Section 1. We also summarize 

the key areas in which increased sedimentation will affect the resource. 

3.1 Williston Reach 

Suspended sediment in the Williston Reach comes from the mainstem upstream, 

beginning at the Fort Peck Dam in Montana, and from the Yellowstone River, which 

flows into the Missouri River near the western edge of the North Dakota/Montana 

border. The sediment load from the Yellowstone River supports near pre-impoundment levels of turbidity in the Williston reach; therefore, the reach exhibits many 

of the characteristics of the pre-impoundment Missouri River (Ryckman, 2000; 

Lambing and Cleasby, 2006; Steven Krentz, 2008, personal communication). When 

this sediment load meets the slow-moving headwaters of Lake Sakakawea, it settles 

out and forms a delta. This reach connects fish that reproduce successfully in the 

Yellowstone River (such as paddlefish, pallid sturgeon, and blue suckers) with the 

Missouri River. 

3.2 Lake Sakakawea 

Lake Sakakawea is a reservoir of approximately 286 kilometers in length (Galat 

et al., 1996). It has a delta that is 61 kilometers in length, formed by the deposition 

of sediment from the Williston reach (Galat et al., 2005). Lake Sakakawea’s waters 

are colder, clearer, deeper, and have a more stable hydrograph (seasonal floods have 

been eliminated; Hesse and Mestl, 1993; Galat and Lipkin, 2000) than the Missouri 

River mainstem before dam construction. The ecology of the Lake Sakakawea delta 

has not been studied intensively (Fred Ryckman, 2008, personal communication). 

However, it has been observed that the waters beyond the delta are clear, and that 

this area supports a large fishery with abundant walleye, northern pike, and sauger 

populations. Paddlefish are often found in Lake Sakakawea, although they do not 

reproduce successfully there (Fred Ryckman, 2008, personal communication; 

Scarnecchia et al., 2008). 

3.3 Garrison Reach 

Whereas the Williston reach contains near pre-regulation levels of sediment due 

to import from the sediment-rich Yellowstone River and from the mainstem upstream, the Garrison reach between Garrison Dam and the headwaters of Lake 

Oahe is relatively deprived of sediment due to the retention of sediment in Lake 

Sakakawea. Major sources of sediment in this reach come from tributaries (MacekRowland, 2000) and from river-bed erosion on the mainstem. Among these tributaries, the Heart River is the most important contributor of sediment (Macek-Rowland, 2000). The Garrison reach is not well-studied, and little is known about the 

ecology of this segment of the river (Steven Krentz, 2008, personal communication). 

3.4 Lake Oahe 

Lake Oahe, formed by the Oahe Dam in South Dakota, is the longest of the six 

Pick-Sloan Reservoirs, 372 kilometers in length (Galat et al., 1996). A sediment load 

from the Garrison reach forms a delta that is 103 kilometers in length (Galat et 

al., 2005). Only a third of Lake Oahe is located within North Dakota, with the remainder in South Dakota. Lake Oahe supports a fishery with abundant walleye, 

northern pike, and sauger populations. Paddlefish are found in Lake Oahe, although 

it is unclear where they reproduce, as they are not known to reproduce in the reservoir itself (Fred Ryckman, 2008, personal communication). 
182 

3.5 Key Areas Where the Resource Could be Impacted by Sedimentation 

An increased sediment load in the reservoirs would mean increased sediment 

aggradation due to the decreased maximum water velocity associated with reservoirs and the considerably limited ability of reservoirs to transport sediment 

downstream. Aggradation would cause deltas to increase in size (Palmieri et al., 

2001, cited in Kaemingk et al., 2007) and could lead to sediment accumulation behind dams. An increased sediment load would also increase turbidity in the interreservoir reaches. In the reservoirs, turbidity would increase in the headwaters 

while the remainder of the reservoir would remain clear, due to the low water velocity in reservoirs that would cause suspended sediment to settle out (Blevins, 2006). 

The impacts on different species of fish and wildlife would not be uniform, as some 

species benefit in some reaches while others are negatively affected. These differences are the result of a particular species’ life-cycle characteristics as they relate 

to each particular portion of the river. 

As we discuss below, many of the key recreation species of fish require clear and 

sediment-free water for their prosperity. Therefore, sedimentation and increased 

turbidity have negative impacts on their populations. However, current conditions 

do allow for abundant recreational fisheries. 

An increased sediment load could presumably have benefits for some of the conservation species that are adapted to life in a turbid environment. However, other 

physical factors being equal, increased sediment loading alone is not likely to be sufficient to restore or support the populations of these species. 

Other conservation species would benefit from an increase in the amount of sandbar habitat available. Increased sedimentation could potentially generate new sandbar habitat; the deficit of sandbar habitat is in many areas a result of reduced sediment load due to sediment retention by dams (NRC, 2002). Colonization of sandbars 

by cottonwood and willow trees constitutes another important part of habitat generation for many species. However, such colonization would require seasonal floods 

of a magnitude commensurate with those of the Missouri River during pre-regulation times, which are now absent (Johnson, 2002; Bovee and Scott, 2002). Thus, increased sedimentation alone may not generate suitable sandbar habitat unless a hydrologic regime that suits colonization by cottonwood and willow trees is allowed to 

occur. 

4.0 LITERATURE AND DATA COLLECTION METHODOLOGY 

Our approach to literature collection was to first conduct as series of informational interviews with key personnel in the following institutions: 

—North Dakota Game and Fish 

—United States Fish and Wildlife Service, Bismarck Office 

—United States Geological Survey 

—University of North Dakota 

—North Dakota State University 

—University of Nebraska 

—United States Army Corps of Engineers, Omaha District 

Through these interviews, we derived a list of the species to evaluate in this section. We were also able to obtain key pieces of literature that reviewed the life-cycle 

of key species in the State of North Dakota. 

The second step was to complete an Internet search using key terms from species 

names and relying on search engines that investigated government, academic, and 

professional Web sites. Through this literature search we were able to obtain some 

reports (government or academic) that described species of interest in States other 

than North Dakota, if the in-State literature on a particular species was lacking. 

The third step of literature collection involved searching through Berger’s extensive database of information on the ecology of the Missouri River. Through our participation with other projects focused on the Missouri River, Berger has assembled 

a large library of peer-reviewed and government documents pertaining to various 

aspects of ecology on the Missouri River. We were able to focus a search of this library for literature that would provide information about the key species in this 

analysis. This library was also useful in establishing the basic ecological situation 

of the Missouri River and in characterizing pre-regulation versus post-regulation 

characteristics and conditions. 

5.0 IDENTIFICATION AND DISCUSSION OF POTENTIAL SILTATION IMPACTS TO FISH AND WILDLIFE 

In this section we discuss the impacts of siltation to fish and wildlife in the 

mainstem Missouri River in North Dakota, broken into the two groups of species 

identified in Section 3. 
183 

3 Recruitment is defined as ‘‘the addition of new individuals to a population by reproduction’’ 

(Smith and Smith, 2008). 

5.1 Conservation Species 

This group consists of seven fish, two reptiles, five birds, and one mammal. All 

of these species have shown enough certainty of decline for them to have been listed 

as species of conservation priority, either at the State or national levels. 

5.1.1. Fish 

All of the seven fish are endemic to the Missouri River mainstem in North Dakota. This means that they have evolved in a highly turbid environment. For some 

species, declines in population have been directly attributed to declines in water turbidity (flathead catfish, all chubs, pallid sturgeon). While the general life-cycle characteristics and habitat needs of these fish species is well-established in the scientific 

literature, fish ecology in the North Dakota portion of the Missouri River mainstem 

is not well-studied (Fred Ryckman, 2008, personal communication; Chris Guy, 2008, 

personal communication). 

However, several ecological conditions are thought to impact the health of conservation priority fish in the Missouri River mainstem in North Dakota. For instance, there is enough information to conclude that siltation has a positive impact 

on some species in some portions of the river, but a negative impact on those same 

species when it occurs elsewhere. This is especially true concerning fish reproduction. Many of the conservation species are gravel spawners (paddlefish, pallid sturgeon, blue sucker), and if gravel substrates become covered with a layer of silt, these 

habitats become unsuitable for the fish species (AFS, 2008). This is especially true 

in areas of the river with low water velocity, such as the reservoirs, where silt may 

easily settle out. In areas of high water velocity, however, it is less of a problem 

because the high water velocity prevents the silt from settling onto the gravel substrate (USFWS, 1993a). 

The Williston reach currently does have high turbidity due to sediment loads from 

the Yellowstone River, while the Garrison reach is relatively deprived of sediment 

due to retention behind Garrison Dam (Galat et al., 2005). 

Blue Sucker 

The blue sucker is a species of Level I conservation priority in North Dakota. The 

species currently occupies Lake Oahe and the Garrison reach. In addition, small 

populations have been found in the Williston reach, but they do not appear to be 

reproducing successfully there. The reasons for this are unclear (Fred Ryckman, 

2008, personal communication). 

Blue suckers are adapted to live in the swift current of large, turbid rivers (Hagen 

et al., 2005). Berry et al. (2004) found that blue suckers used waters of 10 to 50 

nephelometric turbidity units (NTUs) of turbidity. They are mostly found in riffles 

and narrow chutes, and require gravel bottoms free of sediment (Hagen et al., 2005). 

Population decline over the years has been attributed to habitat modification, specifically caused by temperature alteration and turbidity reduction (Berry et al. 2004; 

Hagen et al., 2005). Population recruitment 3 has been observed in the Missouri 

River, however, blue sucker reproduction has never been observed in the mainstem. 

As such, it is likely that the young-of-year fish that add to the blue sucker populations in the mainstem are spawned in the tributaries, after which they migrate 

into the mainstem (Steven Krentz, 2008, personal communication). 

Increases in water turbidity in high-velocity reaches will likely have a positive impact on this species. However, in waters of lower velocity, an increased silt load may 

cause gravel substrates to become covered by silt, resulting in a negative impact on 

blue sucker. 

Flathead, Sicklefin, and Sturgeon Chubs 

Sturgeon and sicklefin chubs are species of Level I conservation priority according 

to the NDWAP, while flathead chubs are species of Level II conservation priority. 

All of these chubs are adapted for life in turbid, free-flowing rivers with an abundance of sloughs, sandbars, and woody debris (Hesse, 1994, cited in Everett et al., 

2004). Turbidity is a major variable affecting sicklefin and sturgeon chub presence 

in rivers (USFWS, 2001; Bonner and Wilde, 2002; Fisher et al., 2002; Everett et al., 

2004). Note that flathead chubs are more likely to use sandbar habitat than sturgeon or sicklefin chubs (Fisher et al., 2002). 

Reduced turbidity is likely the reason why chubs are no longer found in the reservoirs of Lake Sakakawea or Lake Oahe, nor are they found in the Garrison reach 

(Scarnecchia et al., 2002; Fred Ryckman, 2008, personal communication). Their 
184 

presence has been observed in the Williston reach, which retains pre-regulation levels of turbidity (Scarnecchia et al., 2002). 

As chubs are not currently known to inhabit the reservoirs, it is difficult to determine whether increased sediment loading in these reservoirs would serve to re-establish or support their populations. Increased aggradation in the Garrison reach 

might be more likely to have a positive impact on chubs, as this reach, though modified, retains a riverine as opposed to lacustrine character. Particularly given the 

positive association between chub presence and water turbidity (USFWS, 2001; Bonner and Wilde, 2002; Fisher et al., 2002; Everett et al., 2004), it is reasonable to 

predict that increases in turbidity would have a positive impact on these fish, so 

long as this occurs in an environment that is in all other respects inhabitable by 

chubs. The reservoirs do not seem to meet this qualification, while the Garrison 

reach does. However, scientific research on chub reproduction in North Dakota is 

inadequate to fully assess how sedimentation will affect their ability to reproduce 

successfully. 

Flathead Catfish 

Flathead catfish are an endemic species of Level III conservation priority in the 

State of North Dakota. This species is known to use pools with instream structure, 

such as snags, rubble, and bridge supports (Berry et al., 2001). They are commonly 

found in waters with high turbidity (USGS, 1998), and reproduce in holes along the 

river’s banks (Berry et al., 2001). Currently, the flathead catfish of North Dakota 

are known to inhabit Lake Oahe exclusively, and are not found in the other portions 

of the river in the State (Hagen et al., 2005). 

The NDWAP cites reduced turbidity, temperature reduction, and population fragmentation as reasons behind flathead catfish decline in North Dakota (Hagen et al., 

2005). Other studies have placed special emphasis on the role of decreased turbidity 

in flathead catfish decline (USGS, 1998; Berry et al., 2001). As such, increases in 

turbidity would likely have a positive impact on this species, however, it is unknown 

whether increased turbidity alone would be sufficient to restore and support populations of this species and return it to the reaches from which it has been expelled. 

Given its preference for slower waters (Hagen et al., 2005), it may be unrealistic 

to expect flathead catfish to return to areas of high-velocity flow, even if the turbidity in these areas increases. 

Paddlefish 

This species is listed as a species of Level II conservation priority. While it is legal 

to fish for paddlefish, given its conservation status, the volume of the catch is subject to restrictions. 

Paddlefish do not rely on visual cues for spawning, migration, or feeding 

(Firehammer et al., 2001), and typically grow successfully in turbid environments. 

However, sedimentation poses a problem for paddlefish egg-laying. Paddelfish 

spawn in the spring (Hagen et al., 2005) and require clean, well-oxygenated gravel 

substrates in order to deposit eggs successfully (Jennings and Zigler, 2000). Some 

research suggests that paddlefish are particularly susceptible to losing their spawning habitat as gravel substrates are covered with silt (Sparks,1984, Turner and 

Rablais, 1991, Holland-Bartels, 1992, and Schmulbach et al., 1992, cited in Jennings 

and Zigler, 2000). This is likely a reason why they do not spawn in the Missouri 

River reservoirs, where slow-moving currents cause suspended sediment to settle 

out and cover gravel spawning beds (Fred Ryckman, 2008, personal communication). 

Hagen et al. (2005) note that the lower water velocity brought about by the Missouri River reservoirs has allowed silt to cover existing gravel substrates and make 

them unsuitable as reproductive substrates for paddlefish. For this reason, 

paddlefish do not reproduce within the Missouri River reservoirs. Most observed 

paddlefish reproduction occurs in the Yellowstone River. Larvae produced in the 

Yellowstone drift into the Williston reach, and eventually enter into Lake 

Sakakawea (Scarnecchia et al., 2008; Fred Ryckman, 2008, personal communication). 

They do not reproduce successfully within the reservoir, yet adult paddlefish are 

abundant in Lake Sakakawea. Paddlefish are also found in Lake Oahe, however, 

scientists do not know where these fish originate from (Fred Ryckman, 2008, personal communication). 

Therefore, turbidity in high-velocity reaches such as the Williston reach or in tributaries such as the Yellowstone River does not have an adverse impact on 

paddlefish. As reproduction does not occur in the reservoirs anyhow, increased turbidity in the reservoirs is not likely to limit paddlefish populations because they can 

forage successfully in turbid environments. Further research clarifying the importance of the Garrison reach for paddlefish in North Dakota would clarify the poten-
185 

tial impacts of increased sedimentation in that area. Available research suggests 

that increased turbidity in a high-velocity environment benefits paddlefish. 

Pallid Sturgeon 

The pallid sturgeon was listed as a federally-endangered fish in 1990. In addition, 

they are a species of Level II conservation priority in North Dakota. 

Pallid sturgeon are morphologically adapted for benthic dwelling in swift, turbid 

waters (Forbes and Richardson, 1905; Kallemeyn, 1983; Gilbraith et al., 1988). They 

are known to use waters of 31.3 NTU (J. Erickson, 1992, cited in USFWS, 1993b), 

and to have a current velocity of 10 to 30 centimeters per second (J. Erickson, 1992, 

cited in USFWS, 1993b). Young-of-year and juvenile pallid sturgeon use sandbar 

habitat (Yerk and Baxter, 2001, Kapuscinski and Baxter, 2003, and Doyle and 

Starostka, 2003, cited in USFWS, 2003). Mostly they are found over sand or gravel 

substrate (Sheehan et al., 2002 cited in USFWS, 2003; Hagen et al., 2005). The population declines leading to their listing as a federally-endangered species have been 

attributed to widespread habitat destruction throughout their range (Gilbraith et 

al., 1988; Kallemeyn, 1983; NRC, 2002; USFWS, 2003, 2007). 

Little is known about the pallid sturgeon’s reproductive biology (USFWS, 1993b; 

USFWS, 2003). It is thought that they spawn during July and August (Forbes and 

Richardson, 1905) over hard rock, rubble, or gravel substrate (USFWS, 2003). These 

characteristics are similar to the well-studied shovelnose sturgeon (USFWS, 1993b). 

Pallid sturgeon are known to spawn successfully in the relatively unregulated Yellowstone River (Pat Braaten, 2008, personal communication). However, no natural 

pallid sturgeon recruitment has been observed in the Missouri River since monitoring began in earnest approximately 20 years ago (Pat Braaten, 2008, personal 

communication; Chris Guy, 2008, personal communication). Pallid sturgeon larvae 

are known to drift close to the river-bottom (Braaten et al., 2008) and it is hypothesized, though not empirically confirmed, that for this reason larvae are suffocated 

and killed as they move into the sediment-laden and slow-moving delta headwaters 

of Lake Sakakawea after drifting in from the Yellowstone River (Pat Braaten, 2008, 

personal communication; Fred Ryckman, 2008, personal communication). 

The particular effects of siltation on pallid sturgeon are not well understood, and 

would not be uniform across the Missouri River with its diversity of flows, temperatures, and depths. Mitigation measures dealing explicitly with sedimentation as it 

effects pallid sturgeon have not been attempted in North Dakota (Chris Guy, 2008, 

personal communication; Pat Braaten, 2008, personal communication). 

Note that the declines in pallid sturgeon populations have been attributed to habitat destruction throughout their range. This suggests that neither the re-introduction of water turbidity, or increases in siltation, are likely to suffice to restore their 

populations by themselves. 

5.1.2. BIRDS 

Bald Eagle 

The bald eagle was listed as a federally endangered species in 1967, but was 

delisted in 2007. It is a species of Level II conservation priority in North Dakota. 

Bald eagles build their nests in large trees. In North Dakota, cottonwoods are particularly important nest trees and the majority of bald eagles making use of the 

Missouri River mainstem and floodplain habitat use cottonwood trees (Aron, 2005). 

They forage by perching in trees and viewing the water in order to capture fish and 

waterfowl (Steenhof et al., 1980). 

Increases in water turbidity that prevent bald eagles from being able to see fish 

in the water will cause bald eagles to turn to mammals and birds for food (Grubb, 

1995, cited in Stinson et al., 2007). So long as mammal and bird prey is abundant, 

increased turbidity will not have an impact on the foraging success of bald eagles. 

If siltation increases the amount of fresh sandbars, it may lead to an increase in 

cottonwood recruitment, which would benefit bald eagles. 

Golden Eagle 

The golden eagle is a species of Level II conservation priority in North Dakota. 

These birds usually nest on cliffs, but will also nest in cottonwood or green ash 

trees (Hagen et al., 2005). They feed on small animals, primarily mammals (Hagen 

et al., 2005). Current understanding suggests that anthropogenic disturbance, 

caused by hunters, birders, and manmade structures, in addition to toxic chemicals, 

are the biggest threats to golden eagles. Habitat destruction is a problem not because it reduces suitable habitat for golden eagles, but because it limits access to 

food (Hagen et al., 2005). 
186 

If siltation increases the amount of cottonwood trees available by creating more 

riparian habitat, it will have a positive impact on golden eagles. Otherwise, it will 

not have a significant impact on these birds. 

Least Tern 

The least tern was listed as a federally-endangered species in 1985. In addition 

it is a species of Level II conservation priority in North Dakota. 

The least tern adapted to colonial nesting on non-vegetated, shifting sandbars 

within large, alluvial rivers (USFWS, 1990; USFWS, 2003). Dam operations have 

reduced the availability of this habitat for least terns, due to the stabilizing effect 

on hydrology and their tendency to trap suspended sediment necessary for sandbar 

formation downstream (USFWS, 2003). According to USFWS (2000), the least tern’s 

range in North Dakota does not extend into Lake Sakakawea, but is limited to the 

Garrison reach and Lake Oahe. Most research on least tern habitat has been conducted on the lower Missouri River, not in North Dakota (USACE, 2008). 

Because the primary issue responsible for least tern decline is reduced habitat 

availability caused primarily by sediment retention behind dams, increased siltation 

would be a benefit for least terns only if it is able to increase the amount of sandbar 

habitat available. In the Garrison reach, which has a sediment deficit, increased siltation would be particularly beneficial to least terns if it is able to create sandbar 

habitat. Least terns require non-vegetated sandbar habitat, so if fresh sandbars became colonized by vegetation then they would be unsuitable for least tern use. This 

means that a one-time sediment release would not create suitable habitat for least 

terns. The generation of suitable sandbar habitat relies on the natural annual hydrologic peaks, in addition to an unhindered supply of sediment, occurring regularly 

as a constant flow through the system. 

Piping Plover 

The Northern Great Plains population of the piping plover (which includes the entire North Dakota population of the species) was listed as federally endangered in 

1985. As of 2008, they had been changed from a federally endangered species to a 

federally threatened species. This bird is also a species of Level II conservation priority in North Dakota. 

Plovers use beach-like habitat, including sandflats and gravel, with little vegetative cover (less than 20 percent). These habitats are often adjacent to rivers and reservoirs; they can also use natural islands that meet these characteristics (Haig, 

1992). Northern Great Plains piping plovers in the pre-regulation Missouri River 

nested on sandbars and islands (Galat, 2005; Haig et al., 1994). They feed primarily 

on terrestrial invertebrates and benthic worms (Haig, 1992). 

Siltation will benefit piping plovers if it occurs in high-velocity currents where it 

may aggrade to form sandbars and islands. As with the least tern, piping plovers 

require non-vegetated sandbars, and so any sandbar habitat that is formed will be 

unsuitable if it becomes colonized by vegetation. Siltation that does not generate 

sandbar habitat will not affect piping plovers. Thus, as with the least tern, a onetime release of sediment will not suffice to restore sandbar habitat suitable for piping plover. Sandbar habitat will require hydrologic peaks and flows that would 

transport sediment through the system. 

Red-Headed Woodpecker 

The red-headed woodpecker is a species of Level II conservation priority in the 

State of North Dakota. 

Red-headed woodpeckers live in deciduous woodlands in the upland or floodplain 

habitats (Hagen et al., 2005). They make nests anywhere from 5 to 80 feet above 

ground level, in dead oak, ash, maple, elm, sycamore, cottonwood, or willow trees, 

or in utility poles (Hagen et al., 2005). Their diet is composed of insects found in 

decaying wood, corn, nuts, berries, and occasionally the eggs or young birds of other 

passerines (Hagen et al., 2005). 

Siltation will not have an impact on red-headed woodpecker, unless it generates 

an increase in tree recruitment, which would have a positive impact. 

5.1.3. OTHER CONSERVATION SPECIES 

False Map Turtle 

The false map turtle is a species of Level III conservation priority in North Dakota. 

False map turtles rely primarily on large rivers and backwaters for their habitat 

(Bodie et al., 2000). Their decline has been attributed to the reduction and alteration of sandbar habitat in the mainstem Missouri River (Hagen et al., 2005). 

Therefore, siltation will benefit false map turtles if it generates new sandbar habi-
187 

tat. Recall from the discussions on least tern and piping plover that a one-time release of sediment will not suffice to this end. 

Smooth Softshell Turtle 

The smooth softshell turtle is a species of Level III conservation priority in North 

Dakota. 

Smooth softshell turtles rely primarily on moderate to fast streams and rivers 

(Bodie et al., 2000). They are found in Lake Oahe, but have not been observed in 

Lake Sakakawea, nor have they been observed in the Garrison or Williston reaches 

of the river (Hagen et al., 2005). 

North Dakota’s 2005 Wildlife Action Plan suggests that reductions in sandbar 

habitat have been the primary cause of smooth softshell turtle declines. Therefore, 

siltation that results in the generation of sandbar habitat will be beneficial to these 

reptiles. 

River Otter 

The river otter is a species of Level II conservation priority in North Dakota. 

River otters historically occurred throughout aquatic habitats in North Dakota, 

but their populations have declined due to the destruction or modification of riparian habitat, usually for the purposes of economic development of various kinds, including agricultural, residential, or others (Hagen et al., 2005). The current status 

of river otter populations in North Dakota is uncertain, and it is not clear whether 

a viable population exists within the State. However, we include river otters in our 

analysis because the Missouri River is an important waterway through which these 

animals might return to North Dakota from populations in other States (Hagen et 

al., 2005). 

Increased siltation will only affect river otters if it generates riparian habitat, as 

they are known to use this habitat. Decline in riparian and wetland habitat was 

cited in Hagen et al. (2005) as a reason for river otter decline. 

5.2 RECREATIONAL SPECIES 

Walleye, channel catfish, sauger, northern pike, white bass, and Chinook salmon 

are the most important recreational fish species on the Missouri River in North Dakota. Of these six fish species, walleye are the most prized recreation fish. The fisheries for all of these species are thriving under the current sediment regime, although the particular impacts of siltation on the most popular species such as walleye, sauger, and northern pike remain unclear (Fred Ryckman,2008, personal communication). Trapping and hunting occurs for Canada goose, beaver, and muskrat 

(Steve Dyke, personal communication, 2008), so we include these animals as well. 

The methods used to estimate the populations of the recreational fish species are 

outlined in Brooks et al. (2007a, 2007b). Note that the margin of error is likely due 

to a small sample size. 

Academic and government studies reveal that endemic recreational fish that were 

abundant in the pre-regulation Missouri River benefit from the increased turbidity 

brought about by siltation; these include the channel catfish and the sauger. 

For those fish that were introduced or that were artificially made abundant, the 

effects of an increased sediment load and increased turbidity are negative; in this 

group are the northern pike, white bass, Chinook salmon, and walleye. Increases 

in sediment load are thought to be detrimental to these species for two reasons. 

First, these species are all visual predators, and their foraging success decreases in 

turbid waters. Second, their reproductive success requires a rocky or gravel substrate for laying eggs, and if this is coated with a layer of sediment, it becomes unsuitable. Highly-aggraded habitat is therefore unsuitable for them. 

Fisheries for walleye exist in all four segments of the Missouri River mainstem 

in North Dakota. The considerable sedimentation that does occur in the inter-reservoir reaches presumably affects them, but successful fisheries exist nonetheless. 

The sediment-laden waters of the Williston reach deposit their sediment load in the 

61-kilometer delta of Lake Sakakawea. The reservoir beyond the delta is relatively 

clear. Thus, increased siltation in the Williston reach or in the Lake Sakakawea 

delta will only affect the Lake Sakakawea fishery if it is of a volume sufficient to 

significantly increase the length of the delta or to increase the turbidity and siltation of the clear waters beyond the delta. For this reason, siltation in the inter-reservoir reaches will not have an impact on the fishery species unless it is severe. Recall, however, that much about the effects of siltation on fishery species remains uncertain (Fred Ryckman, 2008, personal communication); what is known is that the 

current conditions allow these species to thrive (Brooks et al., 2007a, 2007b; Fred 

Ryckman, 2008, personal communication). 
188 

Walleye 

Walleye are a native fish in the Missouri River basin, although prior to the construction of dams, they were not abundant (Benson, 1968, cited in Bryan, 1995). 

Today, walleye are the major constituent of the recreational fishery on the Missouri River in North Dakota. Eighty-two percent of the anglers on Lake Oahe in 

2006 were found to fish primarily for walleye (Brooks et al., 2007a). Walleye accounted for 98 percent of boat angling and 68 percent of shore angling in 2006 on 

Lake Sakakawea (Brooks et al., 2007b). Total harvest of walleye from Lake 

Sakakawea during 2006 was between 993,482 and 285,871 fish caught by boat anglers, and between 476,051 and 181,468 fish caught by the shore anglers (Brooks 

et al., 2007b). In Lake Oahe, boat anglers caught between 141,951 and 48,719 individual walleyes, while shore anglers caught between 110,344 and 45,125 individuals 

(Brooks et al., 2007a). 

Walleye are visual predators, and as such, high turbidity may impair their ability 

to see their prey and thus to forage successfully. They are also opportunistic predators that prey on a variety of fish species (Lyons and Magnuson, 1987, Vigg et al., 

1991, Jackson, 1992, and Mero, 1992, cited in Bryan, 1995), and during portions of 

the year, their diet may consist primarily of aquatic insects (Kelso, 1973; Swenson, 

1977, Johnson et al., 1988, and Mero, 1992, cited in Bryan, 1995). The most important prey fish are rainbow smelt, spottail shiner, and freshwater drum (Jackson, 

1992, cited in Bryan, 1995). With the exception of freshwater drum, these species 

were introduced to the Missouri River system as forage for walleye and other game 

fish (Galat et al., 2004). They are not adapted to life in a turbid environment. Thus, 

increased turbidity in the clear waters of the reservoirs may have a negative impact 

on these fish, and these effects may carry over to walleye. 

Siltation also has implications for walleye reproduction. This is because walleye 

are broadcast spawners, releasing fertilized eggs into the water column over a rocky 

surface so that they descend into the cracks between rocks and later hatch (Kerr 

et al., 1997, cited in Dustin and Jacobson, 2003). They have also been observed laying eggs over live vegetation (Dustin and Jacobson, 2003). Eggs that land on sand, 

silt, or muck experience high mortality (Johnson, 1961, and Priegel, 1970, cited in 

Dustin and Jacobson, 2003). Therefore, if the rocky surfaces that walleye rely on for 

reproduction become covered by sediment, this reduces their ability to reproduce 

successfully. Siltation of a level sufficient to prevent aquatic plant growth will also 

reduce walleyes’ ability to reproduce successfully over vegetation. 

Another way in which sediment will affect walleye is in its capacity to modify 

temperature. Temperature is an extremely important factor in walleye growth (Armour, 1993, cited in Bryan, 1995), and they cannot reproduce in waters colder than 

6° C (Hokanson, 1977, cited in Bryan, 1995). If the suspended sediment load reduces 

the water temperature below this level during spawning, it will reduce their population. 

The Williston and Garrison reaches have walleye fisheries, and these occur during 

late summer through spring, which are clear-water periods (NDGF, 1998a, 1998b). 

Thus because of effects on foraging and reproduction, increased siltation is likely 

to have a negative effect on walleye populations. However, the walleye fishery in 

Lakes Sakakawea and Oahe is thriving. This is true of Lake Sakakawea despite the 

sediment load from the Williston reach and the delta at the headwaters. The effects 

of siltation on walleye in North Dakota are unclear (Fred Ryckman, 2008, personal 

communication). However, under current conditions their populations are not declining. Increased sediment loads are not likely to be a problem for walleye unless they 

result in increased turbidity in the clear waters of Lakes Sakakawea and/or Oahe. 

Northern Pike 

On Lake Sakakawea in 2006, northern pike accounted for less than 1 percent of 

all boat angling efforts, and 8 percent of all shore angling efforts, representing 7,799 

(∂/¥ 23,305) and 1,116 (∂/¥ 6,737) individual fish, respectively (Brooks et al., 

2007b). On Lake Oahe, northern pike accounted for less than 1 percent of all boat 

angling efforts, and 3 percent of all shore angling efforts (Brooks et al., 2007a). 

These totals (1,884 (∂/¥ 4,674) and 636 (∂/¥ 2,951), respectively) are for individual fish (Brooks et al., 2007a). 

Northern pike thus constitute an important recreational species, and much of 

their life-cycle needs are similar to those of walleye. They are visual predators 

(Polyak, 1957, and Braekvelt, 1975, cited in Inskip, 1982), therefore increases in 

water turbidity affects their ability to detect prey and to forage successfully. Although northern pike will eat a variety of small mammals including invertebrates, 
189 

4 A piscivore is a carnivorous animal which lives on eating fish. 

waterfowl, and small mammals, they are mostly piscivorous,4 with gizzard shad, 

alewife, yellow perch, and trout-perch comprising the bulk of their diet (Inskip, 

1982). Ambush constitutes a major foraging strategy for northern pike; as such, they 

require aquatic plants for cover. Siltation reduces aquatic plant cover (by choking 

out young plants or by reducing light penetration); therefore, it will have a negative 

impact on northern pike. 

Northern pike spawn over vegetation in areas of calm, shallow water (Williamson, 

1942, and Clark, 1950, cited in Inskip, 1982). They can use flooded terrestrial vegetation for this purpose, although they have been observed using backwaters 

(McCarraher and Thomas, 1972, Jarvenpa, 1962a, and Frost and Kipling, 1967, 

cited in Inskip, 1982). Therefore, a reduction in submerged vegetation brought about 

by siltation reduces the northern pike’s ability to spawn successfully. 

The Williston and Garrison reaches have northern pike fisheries occurring during 

late summer through spring, which are clear-water periods (NDGF, 1998a, 1998b). 

If siltation or turbidity increases occur in the clear waters of Lakes Sakakawea 

and/or Oahe, they will have a negative impact on northern pike populations due to 

adverse effects on foraging and reproduction. However, increased siltation in the 

Williston or Garrison reaches will not likely have an impact on northern pike, because unless it is severe, such siltation aggrades in the reservoir deltas once it 

reaches the reservoir from the inter-reservoir reach. This would leave ample clearwater areas in the reservoir for the northern pike fishery to remain. 

Channel Catfish 

In Lake Sakakawea during 2006, only 438 channel catfish were caught by shore 

and boat anglers (Brooks et al., 2007b). However, on Lake Oahe, channel catfish accounted for 3 percent of all boat angling efforts, and 39 percent of all shore angling 

efforts (Brooks et al., 2007a). Brooks et al. (2007a) estimate that 13,346 (∂/¥ 

16,857) channel catfish were caught by boat anglers, and 6,872 (∂/¥ 13,571) channel catfish were caught by shore anglers. 

Channel catfish are a native species throughout the Missouri River basin (Galat 

et al., 2004), and are substrate generalists (Pegg and Pierce, 2002). They use habitat 

in the mainstem, in the floodplain, and in reservoirs (Galat et al., 2004). They feed 

on insects and crustaceans (Walburg, 1975). Channel catfish in turbid water fisheries do not require stocking, and natural recruitment serves to maintain their population (Mosher et al., 2006), suggesting that they can successfully exist in turbid 

environments. 

Because channel catfish are known to thrive in turbid environments, increases in 

turbidity are likely to have a positive impact on their populations in the Missouri 

River in North Dakota. 

Chinook Salmon 

Chinook salmon are a non-native species in the Missouri River system. 

During 2006, Chinook salmon accounted for 1 percent of all boat angling, and 8 

percent of all shore angling on Lake Sakakawea (Brooks et al., 2007a). The totals 

(4,199 (∂/¥ 6,268) and 3,907 (∂/¥ 5,806), respectively) are for individual fish 

(Brooks et al., 2007b). On Lake Oahe during 2006, only 1,121 Chinook salmon were 

caught (Brooks et al., 2007a). 

Chinook salmon lay their eggs over a gravel substrate (Rice, 1960, cited in 

McCullough, 1999). Therefore gravel that becomes covered by sediment is unsuitable 

as spawning ground for Chinook salmon. However, Chinook salmon do not reproduce naturally in the Missouri River in North Dakota, and their population is entirely the result of stocking efforts; therefore, siltation will not affect their ability 

to reproduce. Additionally, turbidity has been shown to reduce the growth of the 

closely-related coho salmon (Sigler et al., 1984). As the Chinook salmon’s popularity 

as a sport fish in Lake Sakakawea reflects a general abundance of this species in 

that reservoir, we may infer that the lack of siltation in Lake Sakakawea is favorable to Chinook salmon. 

Thus, due to the limitations that it places on growth and on spawning, siltation 

is likely to have negative impacts on Chinook salmon. Increased siltation in the reservoirs is likely to have a negative impact on the species for the reasons outlined 

above. Increased siltation in the Williston reach is not likely to affect them unless 

it is severe enough to significantly increase the size of the delta or the turbidity of 

waters in Lake Sakakawea. Increased siltation in the Garrison reach is not likely 

to affect Chinook salmon in an appreciable way. 
190 

Sauger 

Sauger accounted for 2 percent of all boat angling and 4 percent of all shore angling on Lake Oahe during 2006, representing 3,940 (∂/¥ 9,923) and 2,209 (∂/¥ 

7,031) individual fish, respectively (Brooks et al., 2007a). On Lake Sakakawea in 

2006, sauger accounted for 1 percent of all boat angling and less than 1 percent of 

all shore angling, representing 8,363 (∂/¥ 21,394) and 4,588 (∂/¥ 12,654) individual fish, respectively (Brooks et al., 2007b). The Williston reach has a sauger 

fishery as well (NDGF, 1998a). 

Sauger prefer habitat with high physical turbidity (Pflieger, 1975; Graeb, 2006). 

Therefore, other factors being equal, it is possible that increases in water turbidity 

will increase the likelihood of sauger presence. Little is known about sauger reproduction, and so siltation’s effect thereupon cannot be estimated accurately here. 

However, it is known that sauger spawn successfully in the Lewis & Clark Lake 

delta of Nebraska. Therefore, it is possible that an increase in delta habitat brought 

about by siltation will have a positive impact on sauger reproduction (Graeb, 2006). 

Regardless, the current sediment regime allows for productive sauger fisheries 

throughout the Missouri River in North Dakota (NDGF, 1998a, 1998b; Brooks et al., 

2007a, 2007b). 

Gizzard shad are an important prey species for sauger (Graeb, 2006). Therefore, 

siltation will affect sauger in accordance with its effects upon gizzard shad. As gizzard shad are native to the Missouri River mainstem (Galat et al., 2004), it is unlikely that turbidity and high sediment loads have a negative effect upon their populations, so increases in siltation are not likely to affect them. 

Siltation is likely to have a positive effect on sauger populations because is improves foraging habitat. However, the sauger fishery is currently thriving in the 

clear, silt-free waters of Lakes Sakakawea and Oahe. 

White Bass 

In 2006 on Lake Sakakawea, a total of 1,425 white bass were caught by boat and 

shore anglers (Brooks et al., 2007b). During the same year on Lake Oahe, white 

bass accounted for 1 percent of all boat angling efforts, and 4 percent of all shore 

angling efforts (Brooks et al., 2007a). The totals (2,308 (∂/¥ 6,880) and 945 (∂/ 

¥ 5,821), respectively) are for individual fish (Brooks et al., 2007a). 

White bass were introduced into the Missouri River in 1959, 1960, and 1961 

(Ploskey et al., 1994, cited in Beck, 1998). White bass are visual predators and feed 

on zooplankton in the early life stages and then their diet turns to fish and insects 

as growth progresses (Michaletz et al., 1977, cited in Beck, 1998). Juvenile white 

bass are prey for walleye, and have been known to seek cover from these fish in 

stands of aquatic vegetation (Beck, 1998). 

Increased turbidity would have a negative impact on white bass because it would 

reduce their ability to forage successfully. Also, siltation that reduces aquatic vegetation will reduce the amount of cover available for juvenile white bass, so predation 

may increase, further reducing population size. 

Canada Geese 

Canada geese are opportunistic nest-builders, using whatever materials they can 

find, and build nests near open water with low banks (Dewey and Lutz, 2002). If 

no vegetation is present, Canada geese may construct nests in the open, simply by 

depressing the ground with their body weight and laying eggs into it (Dewey and 

Lutz, 2002). These birds feed on grasses, and can be quite flexible in their diet 

(Dewey and Lutz, 2002). 

Siltation is not likely to affect Canada geese unless it reduces the amount of lowbank habitat, which is itself unlikely because silt deposition would create shallowwater habitat that suits Canada geese. Silt deposition might reduce herbaceous 

vegetation, reducing the food available for Canada geese. 

Muskrat 

Muskrats are present on the Missouri River system in North Dakota, and rely on 

riparian habitat for nesting and foraging (Smith, 1996). They create burrows in the 

river’s banks, which can disturb sediment and result in increased turbidity 

(McMasters University, 2008). Muskrats feed primarily upon riparian plants, but 

consume mollusks and crustaceans occasionally (Natureserve, 2008). 

Increased siltation of the mainstem Missouri River will not affect muskrats unless 

it significantly affects the amount of riparian vegetation that is available as food. 

As these animals naturally generate increases turbidity through their burrowing activities, it is not likely that increased turbidity brought about by large sediment 

loads will have a negative impact on them. 
191 

Beavers 

Beavers are known for building their own stream impoundments, which can alter 

the riverine landscape; however, the Missouri River mainstem’s large size and great 

depth prevents beavers from building impoundments on it, and so they instead burrow into the banks and create underwater food caches there (Collen and Gibson, 

2001). While beaver dams may bring about a reduction in water velocity and thereby reduce the sediment carrying capacity of a stream, the absence of beaver dams 

on the Missouri River mainstem prevents this from happening. Beavers feed on riparian plants (Andersen and Cooper, 2000; Collen and Gibson, 2001). 

Siltation will not affect beavers unless it affects the abundance of riparian plants 

that may constitute part of the beavers’ forage base. 

6.0 CONCLUSIONS 

The results of our analysis are summarized below and in Table 1. 

Increased sediment loads are likely to have a positive impact on channel catfish 

and sauger, which are known to inhabit turbid waters. These fish are not currently 

species of conservation priority, and the current sediment regime is allowing them 

to sustain populations. 

Siltation will have no significant impact upon river otters and Canada geese. 

These animals are not directly affected by turbidity. Moreover, the reasons for the 

decline in river otter populations are the complete removal of habitat and changes 

in siltation will not significantly affect this factor. Canada geese are opportunistic 

in their habitat use; however, for the reasons noted in Section 6.2.1, Canada geese 

may be affected by increased siltation, although this is unlikely. 

Siltation will have a positive impact on red-headed woodpeckers, golden eagles, 

and bald eagles only if it increases the amount of riparian forest habitat available, 

other wise it will have no impact. These birds all require riparian forests for their 

habitat. Siltation may contribute to riparian forest habitat by aggrading and creating new surfaces for colonization by cottonwoods and willows, but in the absence 

of natural hydrology this is unlikely to occur. 

Increased sediment loading occurring in the clear waters of reservoirs will have 

a negative impact upon walleye, northern pike, Chinook salmon, and white bass. 

These species are all visual predators and gravel spawners, and increased turbidity 

and increased siltation has negative consequences for them. The current sediment 

regime does allow for an abundant fishery throughout the Missouri River in North 

Dakota. Note that inter-reservoir fisheries for these fish species exist only during 

clear-water seasons (late summer through spring; NDGF, 1998a, 1998b). 

The pallid sturgeon, paddlefish, flathead chub, sicklefin chub, sturgeon chub, and 

blue sucker are adapted to thrive in a highly turbid environment, but cannot be expected to increase in abundance unless other environmental factors are satisfied 

also. The pallid sturgeon, as discussed above, is adapted to life in a turbid environment, however, they do not reproduce successfully in any reaches of the Missouri 

River, even the turbid Williston reach. It is hypothesized that their larval drift habits, which involve larvae drifting close to the river bottom, causes them to undergo 

widespread mortality after they reach deltas. The paddlefish can grow in the Missouri River, but do not reproduce successfully in any reach. It is known that chubs 

require turbid water for their survival, but it is unclear whether this is the only 

reason why they do not inhabit Lakes Sakakawea or Oahe. The blue sucker does 

indeed exist in the reservoirs, but primarily it inhabits the inter-reservoir reaches. 

The least tern, piping plover, smooth softshell turtle, and false map turtle require 

sandbar habitat, and siltation that increases sandbar habitat will be of benefit to 

them. Sandbar habitat is more a result of hydrology than of sediment load. Therefore, NDGF (1998a, 1998b) recommends that flows be managed to allow more sandbar habitat to be created in the inter-reservoir reaches. NDGF, 1998a, suggests that 

‘‘[i]n at least one year out of four, sustained flows of less than 28,000 but greater 

than 40,000 cfs in April, May, and June [would be] sufficient to create and/or scour 

sandbars for terns and plovers’’ (p. 3). Also, in order to be suitable habitat for terns 

and plovers, sandbars must be free of vegetation; USACE has not had complete success in managing sandbar habitat to be free of vegetation (USACE, 2008), although 

further research into feasible techniques is planned for the near future (USACE, 

2008). 
192 

TABLE 6–1.—IMPACT OF SILTATION ON KEY SPECIES 

Positive impact No significant impact 

Positive impact if siltation increases riparian forest habitat; otherwise no impact Negative impact Siltation positive, but require other environ- mental factors as well Positive impact if sil- tation increases sand- bar habitat River sections that the animal pre- dominates in 

Conservation Priority Level I: 

Blue sucker ..................................... ................................ ................................ ................................ ................................ X ................................ Oahe and Garrison Sturgeon chub ................................ ................................ ................................ ................................ ................................ X ................................ Williston only Sicklefin chub ................................. ................................ ................................ ................................ ................................ X ................................ Williston only 

Conservation Priority Level II: 

Bald eagle ...................................... ................................ ................................ X ................................ ................................ ................................ N/A Golden eagle ................................... ................................ ................................ X ................................ ................................ ................................ N/A Least tern ....................................... ................................ ................................ ................................ ................................ ................................ X N/A Piping plover .................................. ................................ ................................ ................................ ................................ ................................ X N/A Red-headed woodpecker ................. ................................ ................................ X ................................ ................................ ................................ N/A River otter ....................................... ................................ X ................................ ................................ ................................ ................................ N/A Flathead chub ................................ ................................ ................................ ................................ ................................ X ................................ Williston Reach only Paddlefish ....................................... ................................ ................................ ................................ ................................ X ................................ Williston, Sakakawea, Oahe Pallid sturgeon ............................... ................................ ................................ ................................ ................................ X ................................ Yellowstone River and Williston 

Conservation Priority Level III: 

Smooth softshell turtle ................... ................................ ................................ ................................ ................................ ................................ X N/A False map turtle ............................. ................................ ................................ ................................ ................................ ................................ X N/A Flathead catfish ............................. ................................ ................................ ................................ ................................ X ................................ Oahe only 

Recreational Species: 

Beaver ............................................. ................................ ................................ ................................ ................................ ................................ ................................ N/A Canada goose ................................. ................................ X ................................ ................................ ................................ ................................ N/A Channel catfish .............................. X ................................ ................................ ................................ ................................ ................................ Oahe Chinook salmon .............................. ................................ ................................ ................................ X ................................ ................................ Sakakawea Muskrat ........................................... ................................ ................................ ................................ ................................ ................................ ................................ N/A Northern pike .................................. ................................ ................................ ................................ X ................................ ................................ Sakakawea Sauger ............................................ X ................................ ................................ ................................ ................................ ................................ Sakakawea, Oahe Walleye ............................................ ................................ ................................ ................................ X ................................ ................................ Sakakawea, Oahe White bass ...................................... ................................ ................................ ................................ X ................................ ................................ Sakakawea, Oahe 
193 

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196 

APPENDIX F—IMPACT OF SILTATION ON FLOOD CONTROL MISSOURI RIVER, NORTH

DAKOTA

1.0 INTRODUCTION 

The Louis Berger Group, Inc. (Berger) was tasked by the U.S. Army Corps of Engineers (USACE) to assess the potential impacts of sedimentation in the Missouri 

River within the State of North Dakota. The assessment was to be based on review 

of relevant existing data and information. The study area was defined by the 

USACE to include the watershed of the mainstem of the Missouri River from the 

North Dakota/South Dakota border on the downstream end to the Montana/North 

Dakota border on the upstream end. This section of the report analyzes the potential impacts of sedimentation on flood control. 

The Garrison and Oahe Dams and their respective reservoirs are part of the Missouri River Mainstem System consisting of six dams in total. The Garrison and 

Oahe Dams were authorized by the Flood Control Act and serve as the main mechanisms for flood control along the Missouri River in the State of North Dakota. 

1.1 Principal Flood Problems 

Principal flood problems were identified in the 2005 Flood Insurance Study (FIS) 

prepared by the Federal Emergency Management Agency (FEMA) for the Bismarck, 

North Dakota area. The FIS attributes the following four conditions as the causes 

or contributing factors to flooding in the area: (1) open-water season flooding from 

Garrison Dam operations; (2) open-water season flooding from tributaries, and other 

residual drainage areas below Garrison Dam, combined with releases from Garrison 

Dam; (3) flooding, resulting from ice jams and ice conditions; and (4) flooding caused 

by aggradation in the upper reaches of the Lake Oahe. 

Major flooding along the Missouri River occurred in 1881, 1887, 1910, 1917, 1938, 

1939, 1943, 1947, 1950 and 1952. As a result of the completion of Garrison Dam 

in 1953, floods of the magnitudes experienced during these events would have a recurrence interval greater than 500 years. 

The maximum peak discharge that has occurred since 1953 on the Missouri River 

was 68,900 cubic feet per second (cfs) at the USGS stream gage at the city of Bismarck. This occurred on July 13, 1975, with an estimated recurrence interval of 75 

years. A more recent flood of record occurred in May 1980, with a peak discharge 

of 18,900 cfs. 

The highest record of flooding at the Bismarck stream gage since completion of 

the Garrison Dam was 14.8 feet, which occurred on January 13, 1983, because of 

ice conditions and ice jams. A discharge of 59,500 cfs was recorded on July 25, 1997. 

These conditions are typical of an event with a recurrence interval of approximately 

10 years. 

1.2 Flood Storage Capacity Losses in Reservoirs 

The Garrison and Oahe Reservoirs have defined zones for flood control, multiple 

uses, and permanent pool. These zones are defined as follows and are shown on Figure 1–1: 

—Exclusive Flood Control Zone.—This zone is the total upper volume of the 

mainstem lakes maintained exclusively for flood control. Water is released from 

this zone as quickly as downstream channel conditions permit so that sufficient 

storage remains available for capturing future inflows. 

—Annual Flood Control and Multiple Use Zone.—This zone is used to store the 

high annual spring and summer inflows to the reservoirs. Later in the year, 

water stored in this zone is released for riverine uses so that the zone is evacuated by the beginning of the next flood season on March 1. Evacuation is accomplished mainly during the summer and fall navigation season. 

—Carryover Multiple Use Zone.—This zone is designed to provide water for all 

uses during drought periods. The zone is operated so that it remains full during 

periods of normal inflow but is gradually drawn down during drought periods. 

—Permanent Pool.—The permanent pool provides the minimal water level necessary to allow the hydropower plants to operate and to provide reserved space 

for sediment storage. It also serves as a minimum pool for recreation and for 

fish and wildlife habitat and as an ensured minimum level for pump diversion 

of water from the reservoirs. 
197 

FIGURE 1–1.—Reservoir Storage Zones 

The Garrison Reservoir has lost 907,000 acre-feet of total storage capacity due to 

accumulated sediments from the time it began operation in 1953 until 1988. The 

Oahe Reservoir has lost 614,000 acre-feet of total storage capacity from the time it 

began operation in 1958 until 1989. Table 1–1 and Figure 1–2 show the storage loss 

by zone. 

FIGURE 1–2.—Reservoir Storage Losses By Zone 
198 

TABLE 1–1.—RESERVOIR STORAGE LOSSES BY ZONE 

Year 

Total Storage Below the Pool Elevation 

(1,000 acre-feet) 

Storage Change Over Time (percent) 

Excl. 

Flood 

Control 

Flood 

Control 

& Multiple Use 

Carryover & 

Multiple 

Use 

Perm. 

Pool 

Excl. 

Flood 

Control 

Flood 

Control & 

Multiple 

Use 

Carryover & 

Multiple 

Use 

Perm. 

Pool 

Total 

Storage 

Loss 

1,000 

acre-ft 

Total 

Storage 

Loss 

(percent) 

Annual 

Loss 

(percent) 

Garrison Reservoir: 

Pool Elev ............................................................................................................................... 1,854 1,850 1,837.5 1,775 1,854 1,850 1,837.5 1,775 ............ ............ ............

1953 ............................................................................................................................. 24,728 23,225 18,917 5,152 .............. .............. ............ .............. ............ ............ ............1958 ............................................................................................................................. 24,504 23,000 18,694 5,004 ¥0 .1 .............. 0.5 2 .9 224 0.9 0.18 1959 ............................................................................................................................. 24,477 22,973 18,670 4,989 ¥0 .1 0 .1 0.6 3 .2 251 1.0 0.17 1964 ............................................................................................................................. 24,355 22,846 18,517 4,981 ¥0 .4 ¥0 .5 1.7 3 .3 373 1.5 0.14 1969 ............................................................................................................................. 24,137 22,635 18,348 4,976 0 .1 0 .5 2.9 3 .4 591 2.4 0.15 1979 ............................................................................................................................. 23,923 22,439 18,209 4,990 0 .6 2 .0 4.0 3 .1 805 3.3 0.13 1988 ............................................................................................................................. 23,821 22,332 18,110 4,980 0 .9 2 .0 4.6 3 .3 907 3.7 0.11 

Oahe Reservoir: 

Pool Elev ............................................................................................................................... 1,620 1,617 1,607.5 1,540 1,620 1,617 1,607.5 1,540 ............ ............ ............

1958 ............................................................................................................................. 23,751 22,649 19,490 5,665 .............. .............. ............ .............. ............ ............ ............1963 ............................................................................................................................. 23,647 22,545 19,386 5,575 .............. .............. 0.1 1 .6 104 0.4 0.09 1968 ............................................................................................................................. 23,507 22,416 19,239 5,521 1 .0 ¥0 .6 0.8 2 .5 244 1.0 0.10 1976 ............................................................................................................................. 23,337 22,240 19,054 5,451 0 .5 ¥0 .9 1.6 3 .8 414 1.7 0.10 1989 ............................................................................................................................. 23,137 22,035 1,883 5,373 .............. ¥1 .3 2.6 5 .2 614 2.6 0.08 

Source: Aggradation, Degradation and Water Quality Conditions, USACE 1993. Data taken from Plate 7, ‘‘Summary of Reservoir Surveys and Associated Storage Loss by Zone’’. 
199 

2.0 LITERATURE AND DATA COLLECTION METHODOLOGY 

Jeff Klein of the North Dakota State Water Commission (NDSWC) was contacted 

to obtain data used to develop the Missouri River hydraulic model, particularly 

channel profile data. Mr. Klein responded by providing components of the hydraulic 

model in Burleigh and Morton Counties. 

Nancy Steinberger, the Regional Engineer for FEMA was contacted to obtain historic flood plain mapping and historic hydraulic modeling of the river, particularly 

the channel profiles from the model input data set. Ms. Steinberger indicated that 

the channel profiles of the river would best be obtained from the Omaha District 

of the USACE, who was responsible for the hydraulic modeling. Ms. Steinberger further indicated that historic flood mapping of the Missouri River in North Dakota 

could be obtained through FEMA but only three counties, Morton, Burleigh, and a 

small portion of Williams, have been updated in recent years. She noted that the 

Williams County update was underway and had not been published yet. Morton, 

Burleigh and Williams County (in the vicinity of the town of Williston) were updated because they contain population centers; the other counties along the Missouri 

River within the State of North Dakota did not have populations high enough to 

warrant updating the FEMA mapping. 

Due to the lack of new flood data all along the Missouri River, analysis in this 

report was limited to the areas where historic and current flood data was available, 

particularly the areas surrounding the City of Bismarck. The analysis can be expanded to include Williams County in the vicinity of the town of Williston once the 

updated flood data becomes available. 

3.0 POTENTIAL SILTATION IMPACTS ON FLOOD CONTROL 

During the design and construction of a reservoir, siltation rates are one of the 

many factors that are considered when determining the expected life of a reservoir. 

Excessive siltation rates are those considered above what is expected when a reservoir is constructed. When excessive siltation occurs, the storage capacity of a flood 

control reservoir is significantly and rapidly decreased. The two most common impacts associated with excessive siltation are: less water available for domestic and 

agricultural use; and decreased flood protection. The most common causes for excessive siltation are accelerated erosion and increased runoff associated with change 

in land use activities throughout the watershed. 

The decrease in storage potential of a reservoir due to siltation can cause increased downstream flood risks. Increases in probability and intensity of flood 

events can result from increased upland erosion, which causes a decrease in hydraulic capacity of a channel due to sedimentation. Changes in land use of upland areas 

may also generate more runoff in a shorter period and potentially increase flood intensity. Agricultural and recreational uses may be impacted by the increased flooding and sediment transport. There may also be an increase in water treatment costs 

where water treatment plants draw raw water from the impacted impoundments, 

streams and rivers. 

There were two FISs prepared by FEMA for Bismarck, North Dakota and the surrounding area. The 1988 FIS for the city of Bismarck and Burleigh County Unincorporated areas was compared to the 2005 FIS for Burleigh County and Unincorporated Areas. The 1988 FIS used an older version of the Hydrologic Engineering 

Centers analysis software (HEC–2) and the 2005 FIS used the HEC River Analysis 

System software (HEC–RAS). The models, which were provided by the NDSWC and 

Houston Engineering, Inc., were run to simulate the 50-year, 100-year, and 500-year 

storm event scenarios. The results of the models were then compared to the data 

within the associated report for verification. 

The flood profiles from the two models were then compared at key milestones 

along the river to determine the change in elevation (Table 3–1). It was found that 

for the 50-year design storm, flood water surface elevations had risen by approximately 1.2 feet at the downstream station and by as much as 1.8 feet within the 

reach. For the 100-year storm, flood elevations had risen by approximately 1.3 feet 

at the downstream station and as much as 1.4 feet within the reach. The model results also yielded that for the 500-year storm, flood elevations had risen as much 

as 1.1 feet at the downstream station. Although these model simulations provided 

verification of the water surface elevation change, they did not provide an explanation for the increase. 

Compilation and review of data from previous studies prepared by the USACE indicates that sediment is accumulating at various locations within the main channel 

of the Missouri River. Table 3–2 shows the segments of river that have experienced 

documented sedimentation. The highlighted segments are located within the reach 

analyzed in the Bismarck FIS or downstream from this reach. The sedimentation 

occurring in these segments could be impacting the flood elevations in the Bismarck 
200 

area. It should be noted that only two of the segments, identified in bold text in 

Table 3–2, fall within the reach bounded by the key milestones identified in Table 

3–1. 
201 

TABLE 3–1.—FLOOD ELEVATION COMPARISON 

Key Milestone River Station 

Flood Elevations, (feet) NAVD Changes in Flood Elevations 

from 1988 to 2005 (feet) 

1988 Flood Data 2005 Flood Data 

50 yr 100 yr 500 yr 50 yr 100 yr 500 yr 50 yr 100 yr 500 yr 

Confluence Apple Creek .................................................................................................................................... 1300.21 1626.7 1627.7 1631.0 1627.9 1629.0 1632.1 1.2 1.3 1.1 Confluence Little Heart River ........................................................................................................................... 1302.22 1628.3 1629.3 1632.8 1629.6 1630.7 1633.8 1.3 1.4 1.0 Confluence Heart River ..................................................................................................................................... 1310.72 1633.7 1634.9 1638.3 1634.5 1635.7 1638.8 0.8 0.9 0.5 Bismarck Expressway ....................................................................................................................................... 1313.41 1635.1 1636.3 1639.8 1636.0 1637.3 1640.4 0.9 1.0 0.6 Memorial Bridge ............................................................................................................................................... 1314.21 1635.4 1636.5 1640.0 1636.3 1637.5 1640.8 0.9 1.0 0.7 Railroad ............................................................................................................................................................ 1314.99 1635.9 1637.0 1640.5 1637.7 1637.9 1641.2 1.8 0.9 0.7 Interstate 94 ..................................................................................................................................................... 1315.49 1636.1 1637.3 1640.7 1636.9 1638.1 1641.5 0.8 0.9 0.8 City of Bismarck Limits .................................................................................................................................... 1317.42 1637.7 1638.9 1642.9 1638.2 1639.6 1643.6 0.5 0.7 0.6 Confluence Burnt Creek .................................................................................................................................... 1319.88 1638.9 1640.0 1643.9 1639.5 1640.8 1644.6 0.6 0.8 0.8 Burleigh County Limits ..................................................................................................................................... 1328.64 1644.0 1645.0 1648.5 1643.7 1644.8 1648.4 ¥0.3 ¥0.2 ¥0.1 

Source.—Elevations are from HEC–2 data and HEC–RAS data from the 1988 and 2005 Flood Insurance Studies, respectively. 
202 

TABLE 3–2.—RIVER SEGMENTS WITH SEDIMENTATION 

STARTING RIVER MILE ENDING RIVER 

MILE 

MILES WITHIN 

SEGMENT 

LEVEL OF 

SEDIMENTATION 

1564 ................................................................................................................ 1548 16 Low

1548 ................................................................................................................ 1534 14 Moderate 

1534 ................................................................................................................ 1521 13 High 

1521 ................................................................................................................ 1489 32 Moderate 

1489 ................................................................................................................ 1470 19 Low

1457 ................................................................................................................ 1453 4 Low 

1438 ................................................................................................................ 1436 2 Low 

1362 ................................................................................................................ 1352 10 Moderate 

1303 ................................................................................................................ 1301 2 Low 

1301 ................................................................................................................ 1297 4 Moderate 

1297 ................................................................................................................ 1290 7 High

1290 ................................................................................................................ 1288 2 Moderate 

1288 ................................................................................................................ 1285 3 Low 

1285 ................................................................................................................ 1282 3 Moderate 

1282 ................................................................................................................ 1270 12 Low

1270 ................................................................................................................ 1248 22 Moderate 

1248 ................................................................................................................ 1232 16 Low

River miles within the Bismarck FIS boundary with sedimentation. 

River miles downstream of the Bismarck FIS boundary with sedimentation. 

Source.—Data taken from Berger Aggradations Area Map; October 2008. 

FIGURE 3–1—Aggradation Based on USACE Studies 

4.0 FLOOD CONTROL MEASURES 

Siltation in the reach between the Garrison Dam and Lake Oahe has resulted in 

increased risk of flooding in the downstream reach between the dam and the headwater of Lake Oahe. Because of this sediment aggradation, the impact of ice dams 

on seasonal flooding is increasing. As a means to counter this impact, careful 

sequenced water releases during the winter months are made to prevent flooding 

caused by ice dams. 

The Missouri River typically freezes in December, and remains frozen until the 

thaw which occurs in March and April. Ice dams can form during freeze-up as well 

as during ice break-up. Initial forming of ice (ice-in) starts at the headwaters of 
203 

Lake Oahe and moves upstream towards Garrison Dam. Ice dams formed during 

break-up are most common downstream of the confluence between the Missouri 

River and the Heart River (river station 1311). According to FEMA (2005), the higher flows in the Heart River during snowmelt or spring rains cause the formation 

of ice dams on the still-frozen Missouri River. With the siltation causing a higher 

river bed elevation and resulting higher ice sheet elevation, flooding impacts are exacerbated as a result. 

The USACE releases water at the Garrison Dam in a controlled manner over the 

winter months to reduce the ice-in and ice-out risk to flooding in the Bismarck/ 

Mandan area. The ice break-up which occurs in March and April can cause ice dams 

which block the flow of water. This issue is compounded when spring thaw and rainfall increases the discharge flow from tributaries into the Missouri River. Proper 

management of water releases is able to help control downstream flooding, but reduced flow during winter months can impact the production of electrical hydropower. 

5.0 CHANNEL GEOMETRY ANALYSIS 

As discussed in Section 3.0, Berger compared the output data from the models associated with the 1988 and 2005 FIS reports and found a trend for higher water 

surface elevations and lower minimum channel bed elevations. Ten river stations, 

which were selected based on their proximity to key milestones identified in the 

aforementioned FIS reports, were selected for a more detailed analysis. The stations 

and their associated water surface and minimum channel elevations are shown in 

Table 5–1 and the differences between the values of the two models are shown in 

Table 5–2. 

TABLE 5–1.—RIVER STATIONS AND ELEVATIONS 

River Station 

1988 FIS DATA 2005 FIS DATA 

Water Surface NAVD 

88 

(feet) 

Minimum 

Channel 

NAVD 88 

(feet) 

Water Surface NAVD 

88 

(feet) 

Minimum 

Channel 

NAVD 88 

(feet) 

1300.21 ......................................................................................................... 1627.72 1598.40 1629.04 1603.40 

1302.22 ......................................................................................................... 1629.31 1601.50 1630.70 1596.10 

1310.72 ......................................................................................................... 1634.85 1611.30 1635.71 1607.70 

1313.41 ......................................................................................................... 1636.27 1608.60 1637.27 1606.30 

1314.21 ......................................................................................................... 1636.53 1602.30 1637.54 1601.50 

1314.99 ......................................................................................................... 1637.00 1605.00 1637.91 1601.90 

1315.49 ......................................................................................................... 1637.25 1602.60 1638.12 1598.00 

1317.42 ......................................................................................................... 1638.90 1610.20 1639.56 1612.60 

1319.88 ......................................................................................................... 1640.02 1612.90 1640.80 1609.50 

1328.64 ......................................................................................................... 1645.00 1616.40 1644.82 1617.10 

As demonstrated in Table 5–2, the majority of the river stations evaluated indicated an increase in water surface elevation. However, a trend for the minimum 

channel elevation could not be established. Because channel geometry and flow 

characteristics are inherently related and constantly changing, Berger then compared the cross-sectional area for each of the 10 river stations to evaluate the channel geometry to determine if excessive erosion or sedimentation occurred between 

the two model years. Changes in the channel geometry will affect water velocity, 

assuming a constant discharge, which in turn influences a river’s ability to transport sediment as bed load, material in contact with the river bed having a diameter 

larger than fine sand; or as suspended load, fine materials such as clay and silt that 

are held in suspension in the water and carried without contact with the river bed. 

As the velocity of the water in a channel increases, the more capacity the water 

has for erosion and transportation of sediment in the channel. In other words, the 

sediment transportation power, or the kinetic energy, of the water is directly proportional to the increased velocity. When discharge is held constant and width decreases, the velocity increases and the channel will tend to deepen by eroding the 

channel bed, which is referred to as scouring. Kinetic energy is decreased as water 

erodes the river channel or moves sediments along the river bed. In addition, some 

of the kinetic energy is lost through turbulence and friction. Once sufficient kinetic 

energy has been expended or lost, the deposition of the sediment load will occur. 
204 

TABLE 5–2.—COMPARISON OF ELEVATIONS 

River Station 

Water Surface 

NAVD 88 

(feet) 

Minimum Channel NAVD 88 

(feet) 

1300.21 ................................................................................................................................... 1.32 5.00 

1302.22 ................................................................................................................................... 1.39 ¥5.40 

1310.72 ................................................................................................................................... 0.86 ¥3.60 

1313.41 ................................................................................................................................... 1.00 ¥2.30 

1314.21 ................................................................................................................................... 1.01 ¥0.80 

1314.99 ................................................................................................................................... 0.91 ¥3.10 

1315.49 ................................................................................................................................... 0.87 ¥4.60 

1317.42 ................................................................................................................................... 0.66 2.40 

1319.88 ................................................................................................................................... 0.78 ¥3.40 

1328.64 ................................................................................................................................... –0.18 0.70 

Studies have demonstrated that for any given discharge, the river channel bed 

will adjust to a quasi-equilibrium condition governed by the kinetic energy transfer 

between channel flows and the local resistance associated with the geometry of the 

river channel, which directly influences sediment transport. The greater the ratio 

of the cross-sectional area of the channel is to the wetted perimeter, the less the 

local resistance will be as there is proportionately less water within the friction zone 

of the channel (near the sides and bed). In other words, the channel geometry will 

stabilize once the water has reached its maximum sediment load for a given discharge. 

One example of particular interest is that water flowing over a spillway will have 

very little sediment as most of it will have settled out upstream of the dam. This 

water then has a lot of kinetic energy and is capable of transporting a large amount 

of sediment. For this reason, channels immediately downstream of impoundments 

are particularly susceptible to the effects associated with erosion. 

The gross cross-sectional areas of the 10 river stations were compared (see Table 

5–3) for the HEC–RAS data for both the 1988 and 2005 FIS models. All sections 

indicate a net increase in cross-sectional area. These values include both the main 

channel and the overbank areas. Detailed analysis of the channel geometry required 

evaluation of the main channel cross-section. 

The cross-sections of the 10 river stations were plotted with the output from the 

HEC–RAS models. The two cross-sections of the main channel from the 1998 and 

2005 FIS models were then visually compared for each of the river stations. The 

results of this analysis are illustrated in Figures 5–1 through 5–10. 

TABLE 5–3.—RIVER STATIONS AND GROSS CROSS-SECTIONAL AREA 

River Station 1988 FIS Area 

(square feet) 

2005 FIS Area 

(square feet) 

Change in Area 

(square feet) 

1300.21 ...................................................................................................... 24,685.40 24,936.13 250.73 

1302.22 ...................................................................................................... 25,136.57 27,422.00 2,285.43 

1310.72 ...................................................................................................... 30,438.93 31,333.79 894.86 

1313.41 ...................................................................................................... 21,768.87 28,165.79 6,396.92 

1314.21 ...................................................................................................... 23,065.15 26,082.67 3,017.52 

1314.99 ...................................................................................................... 17,418.97 19,355.91 1,936.94 

1315.49 ...................................................................................................... 14,456.52 15,614.66 1,158.14 

1317.42 ...................................................................................................... 35,911.24 38,000.80 2,089.56 

1319.88 ...................................................................................................... 24,774.47 27,718.37 2,943.90 

1328.64 ...................................................................................................... 19,530.14 20,203.27 673.13 

Based on the results of the analysis, 7 of the 10 river stations show a net increase 

in cross-sectional area within the main channel. Likewise, 8 of the 10 stations show 

signs that significant scouring and sloughing has occurred. Both scour and sloughing are a normal part of a river’s natural erosion processes. Scour of a river channel 

can occur due to an increased discharge rate, as mentioned previously, when the 

channel geometry is reduced thus increasing the velocity through that section. 

These influences can be temporary, such as an increase in discharge associated with 

a storm event or a decrease in channel area caused by debris or ice dams. Sloughing, also commonly referred to as slumping, is a form of channel bank erosion where 

the sides of a channel collapse and are deposited to the bottom of a channel. The 

main cause of sloughing is saturation of soil associated with a rise in the water surface elevation, often followed by a sudden decrease of the same water elevation. As 
205 

the water surface falls, it creates a pressure imbalance within the saturated soil and 

the resulting forces cause the soil to erode into the channel bed. The soils that collapse into the channel bed are often comprised of fine silts and sands and are therefore more susceptible to scouring. Two of the three areas identified as having a net 

decrease in main channel cross-sectional area are preceded by river stations where 

sloughing appeared to have occurred. 

There is a significant increase in water surface elevation from the 1988 FIS report 

and the 2005 FIS report at the downstream river station. This increase, approximately 1.32 feet, slowly decreases in subsequent upstream river stations until in the 

vicinity of river station 1300.21. However, this does not appear to be attributable 

to a channel geometry based on the 10 river sections analyzed. In fact, the majority 

of the cross-sections indicated an increase in the area of the main channel, either 

through scouring or sloughing, which would lend itself to a fall in the water surface 

elevation. The data suggest that the water surface elevation is either being influenced by a downstream source or an increased initial water surface elevation used 

in the 2005 model. 

It is important to note that this analysis has a finite study area and is limited 

by the accuracy of the data and the HEC–RAS models provided. It should also be 

noted that common industry belief is that this HEC–RAS model, albeit a highly 

versatile tool, is not able to accurately model all dynamics of flood events, especially 

in a highly urbanized watershed. 
206 

FIGURES 5–1 TO 5–4.—River Station Cross-Sections 
207 

FIGURES 5–5 TO 5–8.—River Station Cross-Sections 
208 

FIGURES 5–9 TO 5–10.—River Station Cross-Sections 

6.0 CHANNEL STABILITY ANALYSIS 

Channel and bank stability on the Missouri River is a continual concern as a potential source of sedimentation. Section 33 of the Water Resources Development Act 

of 1988 authorized the USACE to alleviate bank erosion and related problems along 

the Missouri River from Fort Peck Dam, Montana to Ponca State Park, Nebraska. 

The act stated that both structural and nonstructural measures could be used to address bank erosion on the river. As a consequence, the stabilization projects constructed along the river have created concern about the overall cumulative impacts 

of bank stabilization on river issues such as fish and wildlife resources, which resulted in the USACE preparing a report entitled ‘‘Missouri River—Fort Peck Dam 

to Ponca State Park Geomorphological Assessment Related to Bank Stabilization’’ 

(December 2001). The report was prepared as a joint effort by the U.S. Army Engineer Research and Development Center, University of Nottingham and Colorado 

State University (Biedenharn et al). The report studied the potential geomorphic impacts of the bank stabilization program on wildlife habit within the Missouri River 

system with a particular emphasis on the formation and persistence of habitat bars. 

There is a general scarcity of research literature regarding the effect of further 

bank stabilization measures on the sediment supply to the river channel and how 

this affects the bar and island morphology. According to Biedenharn et al. (2001), 

the upper Missouri River contains numerous bars and islands composed primarily 

of material from eroding banks. A report prepared for the USACE by Pokrefke, T.J., 

Abraham, D.A., Hoffman, P.H., Thomas, W.A., Darby, S.E. and Thorne, C.R. entitled 

‘‘Cumulative Erosion Impacts Analysis for the Missouri River Master Water Control 

Manual Review and Update Study’’ (July 1998), attempted to predict how any future 

increases in bank stabilization would affect erosion rates in the four reaches (Fort 

Peck, Garrison, Fort Randall and Gavins Point) on the Missouri River. Of these 

four, the Garrison Reach is the only reach set solely in the State of North Dakota. 

The Pokrefke et al. (1998) report predicted that an exponential relationship exists 

between increasing amounts of bank stabilization and decreasing rates of bank erosion in the three upriver reaches (Fort Peck, Garrison and Fort Randall), primarily 

due to the fact that the upriver reaches are close to a position of dynamic equilibrium and are stabilizing naturally. By comparison, the Gavins Point Reach, which 
209 

is further downriver, has a linear relationship between increasing bank stabilization 

and decreasing bank erosion. 

The Garrison study reach extends from river station 1390 just downstream of the 

Garrison Dam to river station 1311, located just south of Bismarck where the Heart 

River connects to the Missouri River. The reach is regulated by the Garrison Dam. 

The Biedenharn et al. (2001) report states that the bed material in the reach is predominantly sand with occasional outcrops of gravel. The channel in the Garrison 

reach is relatively straight, with a moderate to high degree of braiding with numerous bars and islands. The channel width ranges from about 430 feet to 4,400 feet, 

with an average width of about 2,100 feet. Bank heights within the Garrison Reach 

generally range from about 10 feet to 43 feet, with an average bank height of about 

17 feet. The bank material contains approximately 29 percent fines (silts and clays), 

with the remainder sands (upper limit approximately 1 mm in size). 

The Biedenharn et al. (2001) report studied the Garrison Reach using specific 

gauge sections to study the degradational trend of the reach. Historically, this reach 

followed a degradational pattern after the dam construction was completed in 1953, 

but this degradational trend began to subside in the mid 1970s to early 1980s. The 

report notes that the gauge records suggest that this reach of the river has been 

approaching a state of dynamic equilibrium since the mid 1980s. This is not to say 

that the reach has achieved dynamic equilibrium, as active processes such as widening of the active channel continue to occur, but it is evident that the rate of 

change in degradation is declining. 

The Biedenharn et al. (2001) report investigated the relationship between channel 

widths and the formations of bars and islands by comparing the cumulative distribution for two time periods, 1975 and 1997. In general for the Garrison Reach, 

the channel width in the range of 2,070 feet appeared to be the threshold zone below 

which it is unlikely that bars will exist. Using the collected information for bars and 

island formation in the Garrison Reach, the report attempted to determine a relationship between the percent bank stabilization and the bar and island density, but 

found no obvious trends. 

A follow-up report, built upon the work presented in the Pokrefke (1998) and 

Biedenharn (2001) reports, was prepared under contract to the USACE by HDR Engineering, IIHR-Hydro science & Engineering, Mussetter Engineering and WEST 

Consultants, entitled ‘‘Bank Stabilization Cumulative Impact Analysis Final Technical Report—Fort Peck, Garrison, Fort Randall, and Gavins Point Study Reaches’’ 

(March 2008). The HDR report draws on the USACE’s 1999 Cumulative Environmental Impact Statement (CEIS) for on-going bank stabilization within the Missouri 

River from Fort Peck Dam to Ponca, Nebraska. The CEIS was intended to evaluate 

the cumulative environmental impacts of past and future banks stabilization construction on the Missouri River. The HDR report, formed from the draft Appendix 

C of the CEIS, evaluates the amount of bank stabilization over two time periods and 

the potential relationship between increased bank stabilization and sandbar habitat 

formation in the Missouri River within the four study reaches. The HDR report concluded that there is no correlation between past bank stabilization construction and 

evaluated habitat features. As a result, the USACE declared that there is no 

geomorphologic basis on which to alter the rate or amount of bank stabilization currently being permitted in the Missouri River and postponed the preparation of the 

CEIS. Figure 6–1 (HDR, 2008) shows the vicinity map for the Garrison reach studied in the Biedenharn (2001), Pokrefke (1998) and HDR (2008) reports. 

In studying the Garrison Reach, the HDR (2008) report utilized data recorded 

from five stream gauge locations, two sets of aerial photography taken 17 years 

apart, channel cross-section survey data, and HEC–RAS model data. The planform 

analysis performed in the study took into account variables such as channel top 

width, annual flow, bank material, channel bed material to determine the river 

trends within each study reach. 

The HDR (2008) report presented a table (Table 1–7, Revetment by Study Reach) 

showing the miles of revetment installed for each study reach and the time periods 

during which the revetment was installed. The information was based upon a revetment inventory performed as part of the HDR study, using a database of bank stabilization constructed by USACE and authorized by USACE under section 404 of 

the Clean Water Act, supplemented by videotape observations of bank stabilization 

of both banks of each study reach. The table summarized the percentage of bankline 

protected, which is interpreted in the report as the amount of historic channel high 

bank stabilized. The historic channel high banks are stated in the report to be the 

outer boundaries of a developing, new flood plain. The report recognizes that the 

remnant river has a much smaller main channel which generally migrates within 

the banks of the historic channel. The historic or pre-dam river changed signifi-
210 

cantly with construction and operation of the mainstem dams. The revetment identified in the HDR report for the Garrison Reach is shown in Table 6–1 below. 

FIGURE 6–1.—Vicinity Map for Garrison Study Reach (HDR, 2008) 
211 

TABLE 6–1.—REVETMENT, GARRISON REACH 

Study Reach Revetment 

(miles) 1 Year Installed 

Total Study 

Reach River 

Miles, Both 

Banks 

Bankline Protected (percent) 2

Garrison 3 4 .................................................................... 24.0 

5.6 

1976–1985 

1985–1999 

104.2 

104.2 

2 23.0 

5.4 

Source: Table 1–7, HDR Report (2008). 

1 The amount of revetment is the amount that exists within the geomorphic reaches, not the total stabilization that may exist within the 

total reach as some areas outside the geomorphic study reach have been stabilized. 2 The percent of bankline protected reflects the total amount on high bank that is stabilized. Some of this bankline is no longer adjacent to the active flow channel. 3 There were approximately 8 miles of bank stabilization constructed in the Garrison Study Reach prior to 1976, during what is considered 

the pre-revetment study period. 4 The 8 miles of bank stabilization completed prior to 1976 represent about 8 percent of the bankline in the Garrison Study Reach, which 

means that 15 percent of the bankline was actually stabilized between 1976 and 1985. 

The analysis in the HDR (2008) report measures total flood plain erosion. Some 

of this erosion is degradation of the new main channel (particularly immediately 

downstream of a dam); some erosion is where the new channel is widening within 

its new flood plain, and some erosion is where the new channel is widening its new 

flood plain via erosion of the historic channel bank. 

The nature of the Missouri River and its channel planform is that of a meandering stream, as opposed to a braided stream. The difference between meandering 

and braided is shown in Figure 6–2 (HDR, 2008). The terms are defined in a 

USACE report by E.W. Lane entitled ‘‘A Study of the Shape of Channels Formed 

by Natural Streams Flowing in Erodible Material M.R.D. Sediment Report Series 

9’’ (1957) as follows: ‘‘a braided stream is characterized by having a number of alluvial channels with bars or islands between meeting and dividing again, and presenting from the air the intertwining effect of a braid’’ and ‘‘a meandering stream 

is one whose channel alignment consists principally of pronounced bends, the shapes 

of which have not been determined predominantly by the varying nature of the terrain through which the channel passes.’’ It is important to note that the Lane report 

indicated that, prior to construction of the five lower mainstem dams, the Missouri 

River exhibited characteristics closer to a meandering stream. This conclusion was 

based upon plotting a number of U.S. rivers to determine the relationship between 

slope and mean discharge and a stream’s tendency to exhibit a braided or meandering planform. The HDR (2008) report points out the popular misconception held 

by many that the pre-dam construction Missouri River was a braided river due to 

the numerous sandbars and shallow water habitat. 

Thus, the Missouri River which flows today is classified as a meandering steam, 

but has changed from its original meandering stream nature before the dam construction. The Missouri River floodplains of today are primarily confined to the historic channel, which is several thousand feet wide compared to the several-mile-wide 

historic floodplain. The HDR report presents a floodplain analysis which demonstrates that flows in excess of the 500-year discharge flow are needed to produce 

overbank flooding of the historic floodplain in the study reaches where degradation 

has occurred. The dams have, in effect, completely eliminated vast flooding of the 

historic flood plain. Post-dam construction degradation has effectively eliminated inundation of this new flood plain in the Garrison Reach, except during very high flow 

periods, such as those experienced in the late 1990s. 

Analysis of the placement of bank stabilization on the Missouri River was assumed to be only where the river, as defined by the main channel, would come in 

contact with the outside edge of the new, developing flood plain boundary (historic 

channel bank). As such, the main channel is free to meander within the new flood 

plain which is the new natural process related to post-dam construction conditions. 

Figure 6–3 (HDR, 2008) shows an aerial view of the Missouri River floodplain along 

the Garrison Reach at river station 1351.7. The new floodplain is shown within the 

historic channel with the historic floodplain displayed outside of the new floodplain. 
212 

FIGURE 6–2.—Types of Channel Planform (HDR, 2008) 

A cross-section view of the Missouri River along the Garrison Reach at river station 1362.7 is shown in Figure 6–4 (HDR, 2008). The vertical scale depicts the elevation of the channel and the new high banks and compares the cross-section from 

two study periods, 1976 and 1999. It demonstrates the changes which take place 

between 1976 and 1999, showing the main channel migrating from one side of the 

flood plain to the other. Degradation with the bank station is also seen in Figure 

6–4, as well as limited erosion on the channel banks. Figures 6–3 and 6–4 support 

the concept that stabilizing the high bank of the old channel still allows the river 

to migrate within the high banks of the old channel. This allows the sandbars, islands and attached habitat within the historic high banks to erode, with eroded material then deposited downstream. The HDR report states that although analysis is 

unable to measure how this stabilization might affect the trend toward dynamic 

equilibrium, the local effect of this stabilization is eliminated when the main channel migrates away from the stabilization location. 

Erosion of the bank and bed was analyzed for the Garrison Reach by Biedenharn 

et al. (2001). The erosion rate was estimated by summing the left and right bank 

erosion rates for each geomorphic reach length. Bank erosion rates were estimated 

based upon measurement of the area of bankline eroded as evidenced by aerial photographs or through analysis of channel cross-section surveys. From analysis of the 

erosion rates presented in Biedenharn (2001), the report published in Environmental Conservation in 2000 by F.D. Shields, A. Simon and L.J. Steffen entitled 

‘‘Reservoir Effects on Downstream River Channel Migration,’’ concluded that the 

mean erosion rate in the Garrison Reach has decreased more than fourfold since the 

closure of Garrison Dam. The Shields et al. (2000) report also stated that much of 

the reach has experienced net channel widening and deposition rates of alluvial material to form islands and bars have decreased from 408 to 3.2 acres/year. The effect 

of the Garrison Dam has been to a reduction in magnitude of the Missouri River 

high flows in this reach as well as a change in timing (from April to July pre-dam 
213 

to February to March post-dam). The resulting control by the dam in reducing higher flows has acted to reduce overbank flows. The HDR (2008) report concluded that 

channel changes must occur as a result of processes acting only on the banks, including a loss of sedimentation by mass wasting due to a lack of prolonged periods 

of high-stage saturated banks. 

The HDR (2008) report assessed the impact of increased bank stabilization within 

the Garrison Reach. The upstream and downstream controls (mainstem dams) provide upstream clear-water release and a downstream backwater. This results in 

scouring and lowering of the degradation zone portion of the channel in the upstream reaches and an aggradational effect in the lower portion of the reach. The 

elevation of the channel bed is raised in the aggradation zone and the channel begins to display braided characteristics within a meandering regime as it becomes 

wider and shallower, a result of the backwater condition and delta formation at the 

headwater of Lake Oahe. 

The banks along the Garrison Reach generally are composed of fine sands, while 

the channel bed is composed of coarser sands and cobbles. The channel bed has 

changed since the construction of the mainstem dams, as the channel bed material 

in the degradation zone has become coarser. This increase is a result of sedimentfree releases from the Garrison Dam removing the fines and leaving the coarser material to remain, in order to maintain the river’s sediment load. Further downstream, this condition becomes less prevalent as the river carries more sediment. 

Upon reaching the depositional zone, the channel beds are comprised of increasingly 

finer material. 

FIGURE 6–3.—Missouri River Floodplain, Garrison Study Reach (HDR, 2008) 
214 

FIGURE 6–4.—Cross-Section at River Station 1362.7, Garrison Study Reach (HDR, 

2008) 

The bank stabilization features along the Garrison Reach were constructed to prevent bank failure and as a result, serve to limit the bank materials from entering 

the river. The HDR (2008) report states that, in general, placing rock or other stabilization features may not totally prevent movement of bank materials. The effectiveness of the bank stabilization features depends on the structure’s construction. 

It is possible that fines may be ‘‘piped’’ through the stabilization structure or that 

rock may be undersized and move as result from river flow impacting it. Also, stabilization features may be outflanked or undercut by the river flow. Rock that may 

have been initially sized properly during installation may become undersized due 

to freeze-thaw action and aging. However, HDR (2008) does acknowledge that, in 

general, most bank stabilization structures tend to prevent most bank erosion and 

can be considered effective for their intended purpose. 

The HDR (2008) report concludes that bank and channels may experience erosion 

immediately downstream of bank stabilization structures through several mechanisms. Bank stabilization structures immediately downstream of the dam may prevent the erosive, sediment-free dam discharge from removing bank material in this 

location, resulting in an increased channel erosion pressure and relocating the bank 

erosion zone further downstream. Generally, this is most pronounced in the first 

geomorphic reach below the dam. 

Bank stabilization structures prevent the widening of the channel. This prevents 

the reduction in stream power and relief of shear stress on the channel bed from 

taking place if the channel were allowed to widen. However, because bank stabilization has been constructed only where the new main channel of the river is in contact 

with historic high banks of the river, the new channel is free to migrate away from 

the stabilized bank. 

A hardened outer bank may induce secondary currents, potentially causing erosion or scouring along the toe of the outer bank and increasing erosion at the end, 

or flank, of the hardened bank. Further, a hardened bank may also induce erosion 

immediately downstream as a result of changes in either the roughness or the current direction. 

The HDR (2008) report summarizes that the channel will tend to stabilize over 

time in the erosion-related mechanisms discussed above. The Garrison Reach con-
215 

tains approximately 29 percent bank stabilization coverage and the bank erosion 

rate within this reach is in a decreasing trend. 

7.0 ADDITIONAL ANALYSIS 

The FEMA floodplain mapping and HEC–RAS model output were analyzed to 

compare limits of current versus historic flood inundation for the 100-year storm 

event. This comparison was conducted for the river’s extent within Burleigh County 

as well as within just the Bismarck city limits. Table 7–1 compares the areas of the 

100-year flood inundation between the 1985 FIS to the 2005 FIS. 

TABLE 7–1.—FLOODPLAIN AREA COMPARISON 

Burleigh County Bismarck City Limits 

1985 100-year Floodplain—28 mi2 1985 100-year Floodplain—2.7 mi2

2005 100-year Floodplain—36 mi2 2005 100-year Floodplain—3.6 mi2

mi2 = square miles 

The area of the 100-year floodplain has increased by nearly 28.6 percent within 

Burleigh County from the 1985 FIS to the 2005 FIS. The floodplain area within the 

Bismarck city limits has increased by approximately 18.5 percent and accounts for 

approximately 6.3 percent of the net increase within the county. This is of particular 

concern to property owners whose property now lies within the floodplain. Two of 

the potential impacts for property owners associated with this are devaluation of the 

property and the requirement to purchase flood insurance. Homes, businesses, and 

agricultural land are among the types of properties most heavily affected by the 

floodplain area increase. 

As discussed in the previous sections, increased water surface elevations and increased floodplain area could be the result of areas with high aggradation and/or 

the natural morphology of the river changing and/or restricting the channel’s ability 

to convey the flow associated with a particular storm event. 

8.0 SUMMARY AND RECOMMENDATIONS 

This report assesses the potential impacts of siltation in the Missouri River Basin 

within the State of North Dakota on flood control. The report incorporates the review of relevant existing data and information from prior studies and research programs. As defined by the U.S. Army Corps of Engineers (USACE), the study area 

includes the watershed of the mainstem of the Missouri River border from the North 

Dakota/South Dakota border on the downsteam end and the Montana/North Dakota 

border on the upstream end. Included with this study area are the Garrison and 

Oahe dams and the reservoirs associated with each dam, Lake Sakakawea and Lake 

Oahe, respectively. 

The Garrison and Oahe Reservoirs have defined zones for flood control, multiple 

uses, and permanent pool. These zones are utilized to control flow on the Missouri 

River and meet multiple and potentially conflicting goals. 

Flood control issues within the Missouri River for the Bismarck, North Dakota 

area are caused or affected by: (1) open-water season flooding from Garrison Dam 

operations; (2) open-water season flooding from tributaries, and other residual 

drainage areas below Garrison Dam, combined with releases from Garrison Dam; 

(3) flooding, resulting from ice jams and ice conditions; and (4) flooding caused by 

aggradation in the upper reaches of Lake Oahe. 

This report reviews Flood Insurance Studies (FIS) prepared by the Federal Emergency Management Agency (FEMA) for the Bismarck, North Dakota area to analyze 

changes in water surface elevation and its affects on flooding. 

Siltation in the reach between the Garrison Dam and Lake Oahe has resulted in 

increased risk of flooding in the downstream reach between the dam and the headwater of Lake Oahe. Because of this sediment aggradation, the impact of ice dams 

on seasonal flooding is increased. As a means to counter this impact, careful 

sequenced water releases during the winter months are made to prevent flooding 

caused by ice dams. Water release from the Garrison Dam is also used to provide 

flood control during other seasons as well. 

Evaluation of the data from the 1998 and 2005 FIS reports indicates that the 

water surface elevation has increased. Analysis of the channel geometry was conducted at ten river stations, which revealed that the net cross-sectional area of the 

river channel has increased at most of the river sections from the 1998 model to 

the 2005 model. This is likely the result of erosion in the form of scour and sloughing. 
216 

The changes in channel geometry are likely not the cause of the increase in the 

water surface elevation. The data suggest that the water surface elevation is either 

being influenced by a downstream source or an increased initial water surface elevation used in the 2005 model. 

Channel and bank stability on the Missouri River is a concern as a potential 

source of sedimentation. Stabilization projects, including structural and non-structural measures, constructed along the river for the purposes of alleviating bank erosion (authorized by section 33 of the Water Resources Development Act of 1988), 

have created concern about the overall cumulative impacts of bank stabilization on 

river issues, such as fish and wildlife, recreation usage, and flood zone control. 

Within the Garrison Reach, the upstream and downstream controls (mainstem 

dams) provide upstream clear-water release and a downstream backwater. This results in scouring and lowering of the degradation zone portion of the channel in the 

upstream reaches and an aggradational effect in the lower portion of the reach. The 

elevation of the channel bed is raised in the aggradation zone and the channel begins to display braided characteristics within a meandering regime as it becomes 

wider and shallower, a result of the backwater condition and delta formation at the 

headwater of Lake Oahe. 

The impact of increased bank stabilization within the Garrison Reach appears to 

result in a decreasing rate of bank erosion within the reach. The Garrison Reach 

contains approximately 29 percent bank stabilization coverage. 

Table 8–1 summarizes the impacts evaluated in this report and provides recommendations on how to address these impacts related to sedimentation. 
217 

TABLE 8–1.—IMPACT SUMMARY AND RECOMMENDATIONS 

Impact Significance Timeline Recommendation 

Reduced storage capacity in Oahe and Garrison Reservoirs .. Significant .................... Near term (1 to 5 years) ....... Continue to study potential methods to reduce aggradation upstream of reservoirs Aggradation of sediment within main channel ........................ Significant .................... Near term ............................... Study impacts of dredging and identify specific sections of channel downstream of 

Bismark which could benefit from limited dredging program 

Aggradation of sediment raises impact of ice dams on seasonal flooding. Significant in some areas. Near term ............................... Continue sequenced water release during winter months and identify when ineffective to make necessary corrections Cumulative effects of stabilization projects on river issues ... Minor Significance ....... Long term .............................. Continue to study cumulative effects of bank stabilization on fish and wildlife, new or 

on-going stabilization projects to include eco-friendly design techniques 

Channel stability/geometry ....................................................... Possibly Significant ..... Near term ............................... Additional study needed to determine reaches most impacted from sloughing and 

slumping 

Channel stability ....................................................................... Possibly Significant ..... Near term ............................... Identify reaches where eco-friendly bank stabilization techniques can be applied and 

will achieve reduction of aggradation downstream 
218 

9.0 REFERENCES 

Biedenharn, D.S., R.S. Soileau, L.C. Hubbard, P.H. Hoffman, C.R. Throne, C.C. 

Bromley, and C.C. Watson, December 2001. Missouri River—Fort Peck Dam to 

Ponca State Park Geomorphological Assessment Related to Bank Stabilization. U.S. 

Army Corps of Engineers Omaha District. 

Dey, S.K., July 2008. River Bank Erosion. Working paper. Khulna University. 

http://www.scribd.com/doc/4395500/River-Bank-Erosion. 

FEMA. September 1985. Flood Insurance Study—City of Bismarck, North Dakota 

Burleigh County. Community Number 380149. Federal Emergency Management 

Agency. 

FEMA. September 1985. Flood Insurance Study—Burleigh County, North Dakota 

Unincorporated Areas. Community Number 380017. Federal Emergency Management Agency. 

FEMA. July 2005. Flood Insurance Study—Burleigh County, North Dakota and 

Incorporated Areas. FIS Number 38015CV000A. Federal Emergency Management 

Agency. 

HDR Engineering, IIHR-Hydroscience & Engineering, Mussetter Engineering and 

WEST Consultants, March 2008. Bank Stabilization Cumulative Impact Analysis 

Final Technical Report—Fort Peck, Garrison, Fort Randall, and Gavins Point Study 

Reaches. U.S. Army Corps of Engineers Omaha District. 

Lane, E.W., 1957. A Study of the Shape of Channels Formed by Natural Streams 

Flowing in Erodible Material, M.R.D. Sediment Series Report 9. 

Muller, R,, April 2000. The Importance of Regulating the discharge of the Reservoir at the End of a Heavy Rainfall Period. Two Lakes Dreams Realized. http:// 

www.twolakesms.com/AprillSlough.htm. 

Pokrefke, T.J., D.A. Abraham, P.H. Hoffman, W.A. Thomas, S.E. Darby, and C.R. 

Thorne, July 1998. Cumulative Erosion Impacts Analysis for the Missouri River 

Master Water Control Manual Review and Update Study. U.S. Army Corps of Engineers Omaha District. 

Remus, J., 2008, Sedimentation in the Upper Missouri River Basin. U.S. Army 

Corps of Engineers. http://watercenter.unl.edu/MoRiverMainstem/Sedimentation.asp 

Accessed November 20, 2008. 

Shields, F.D., A. Simon and L.J. Steffen, 2000. Reservoir Effects on Downstream 

River Channel Migration. Environmental Conservation 27(1): 54–66. 

USACE. 1993. Aggradation, Degradation, and Water Quality Conditions: Missouri 

River Mainstem Reservoir System. U.S. Army Corps of Engineers Omaha District. 

USACE. 2001 Missouri River—Fort Peck Dam to Ponca State Park 

Geomorphological Assessment Related to Bank Stabilization. U.S. Army Corps of Engineers Omaha District. 

USACE, Coastal and Hydraulics Laboratory. Bank Sloughing. http:// 

chl.erdc.usace.army.mil/erosion. 

Contacts 

Jeff Klein, State NFIP Coordinator North Dakota State Water Commission 

jklein@nd.gov 701–328–4898 

Bruce Englehardt, Investigations Section Chief North Dakota State Water Commission bengelhardt@nd.gov 701–328–4958 

Nancy Steinberger, Regional Engineer FEMA in Denver 

nancy.steinberger@dhs.gov 303–235–4992 

Gregg Thielman, P.E. Houston Engineering Inc. 

gthiel@houstonengineeringinc.com 701–237–5065 

APPENDIX G—IMPACTS OF SILTATION OF THE MISSOURI RIVER ON INDIAN AND NONINDIAN HISTORICAL AND CULTURAL SITES IN NORTH DAKOTA

1.0 INTRODUCTION 

Berger was tasked by the U.S. Army Corps of Engineers (USACE) to assess the 

potential impacts of sedimentation in the Missouri River within the State of North 

Dakota. This assessment is intended to meet the level of effort defined in the Missouri River Protection and Improvement Act. The assessment was to be based on 

review of relevant existing data and information. The study area was defined by the 

USACE to include the watershed of the mainstem of the Missouri River from the 

North Dakota/South Dakota border on the downstream end to the Montana/North 

Dakota border on the upstream end (Figure 1–1). This report analyzes the potential 

impacts of sedimentation on Indian and non-Indian historical and cultural sites. 

This appendix is a brief report that describes the potential impacts to Indian and 

non-Indian cultural resource sites. It provides a summary of the types and locations 

of the records that were consulted and a description of the qualifying properties 
219 

1To protect the cultural resources, location information is not included. 

within the project area. The project area is considered the areas of potential 

aggradation or siltation (Figure 1–2 through Figure 1–5). The area possessing the 

potential for Indian and non-Indian sites is known as the area of potential effects 

(APE). For this assessment, the APE is considered to be the area between the historic low water mark in 2007 and the ordinary high water mark at Lake Sakakawea 

(1,850.0 feet above mean sea level—msl) (USACE 2006a) and Lake Oahe (1,620 feet 

msl) (USACE 2004a).1 However, the research conducted by USACE includes all sites 

within the footprint of Lake Oahe and Lake Sakakawea, and are not separated into 

the portion of the shoreline between the low and high water marks. 

The report identifies the impacts to cultural resources that should be monitored 

and/or mitigated as a result of siltation along waterways and reservoir margins to 

comply with various statutes, regulations, and USACE policies. Such impacts include deposition of sediments on extant Indian and non-Indian historical and cultural sites. In some cases, a layer of sediment covering a cultural site is beneficial 

because it protects the site from weathering, erosion, and intentional or unintentional human actions. For standing structures, the impact may be considered adverse because moisture and sediments can destroy foundations and walls. Along reservoir margins, siltation followed by fluctuation in water levels tends to cause more 

damage to sites because of newly created cut banks and erosion. The integrity of 

sites is damaged and much cultural and scientific data are lost. 

FIGURE 1–1.—Location of Study Area 
220 

FIGURE 1–2.—Aggradation Area Map 1 
221 

FIGURE 1–3.—Aggradation Area Map 2 
222 

FIGURE 1–4.—Aggradation Area Map 3 
223 

FIGURE 1–5.—Aggradation Area Map 4 
224 

2.0 METHODOLOGY 

2.1 Literature and Data Search 

To identify data on cultural resources, Berger performed a review of the records 

on file at the following agencies and repositories, as available: 

—USACE records repository (provided by USACE personnel) 

—North Dakota State Historic Preservation Office (NDSHPO) 

—Appropriate Tribal Historic Preservation Officers (THPO) 

Berger entered information on all properties located within the APE into a database, including all properties listed in the National Register of Historic Places (National Register); properties determined eligible for listing by the Keeper of the National Register; properties in the process of being nominated to the National Register; properties determined eligible by consensus determination by the SHPO; and 

properties identified in the SHPO inventory as meeting the National Register criteria. 

2.2 Analysis 

The potential impacts on and relationships to Indian and non-Indian historical 

and cultural sites were analyzed in terms of duration (short-term versus long-term) 

and magnitude of effects to significant resources. Significant resources are those determined to meet specific evaluation criteria contained in 36 Code of Federal Regulations (CFR) 60.4—Criteria for Evaluation: (a) that are associated with events that 

have made a significant contribution to the broad patterns of our history; or (b) that 

are associated with the lives of persons significant in our past; or (c) that embody 

the distinctive characteristics of a type, period, or method of construction, or that 

represent the work of a master, or that possess high artistic values, or that represent a significant and distinguishable entity whose components may lack individual distinction; or (d) that have yielded, or may be likely to yield, information 

important in prehistory or history. 

Sites that meet at least one of the criteria are considered eligible for inclusion in 

the National Register and are afforded a level of protection by Federal and State 

agencies. 

The report also contains recommendations for solutions to siltation with respect 

to cultural resource sites. 

3.0 BACKGROUND AND CULTURE HISTORY 

3.1 Prehistoric Period 

The prehistory of the Great Plains is divided into five general time periods consisting of: the Paleo-Indian, Plains Archaic, Plains Woodland, Plains Village, and 

the Historic (NDSHPO 2003; USACE 2004b; USACE 2006b). The project area may 

either contain the physical remains of prehistoric properties or the potential to harbor such properties. The physical remains of past human occupation occurring within the project area are identified as sites. The contents of a site and its component 

parts are described as artifacts or features. An artifact is defined as an object than 

can be carried off such as a projectile point or pottery sherd and a feature is defined 

as an object that is non-removable without mechanical means, such as a structure 

or rock art panel. The manner in which ancient people manufactured tools, constructed shelters, or domesticated wild plants is an important aspect of understanding a cultural group’s development through time. 

The Missouri River watershed within central North Dakota contains a diverse and 

in-depth cultural history. Numerous American Indian tribes containing extensive 

oral traditions have identified properties within, and in close proximity to, the 

project area. These properties consist of places where events significant to the development of their culture have occurred and are referred to as traditional cultural 

properties (TCPs). Through the examination of these oral traditions, in conjunction 

with linguistic and archaeological studies, we can gain a better insight to which native cultural group(s) may potentially be affiliated with the prehistoric properties 

within the project area. 

The Division of Historic Preservation of the State Historical Society of North Dakota published Historic Preservation in North Dakota, II: A Statewide Comprehensive Plan, which divides the State into 13 study units for archaeological research. 

The Missouri River and associated reservoirs fall primarily within the Garrison, 

Souris River, and Bismarck Study Units. The Division separates the cultural prehistory of North Dakota into five distinct themes based on a cultural chronology 

spanning approximately 11,500 years (NDSHPO 2003). The Cultural Resource Management Plans (CRMPs) for Lake Sakakawea and Lake Oahe developed by USACE 

also define five prehistoric periods that differ slightly from the Division of Historic 
225 

Preservation (USACE 2004b; USACE 2006b). The categories of both the NDSHPO 

and USACE are shown in Table 3–1. 

TABLE 3–1.—PREHISTORIC CHRONOLOGIES OF NORTH DAKOTA 

Cultural Period NDSHPO Chronology USACE Chronology 

Pre-Clovis ............................................... N/A ......................................................... Prior to 13,000 B.C. 

Paleo-Indian ........................................... 9,500–5,500 B.C. .................................. 13,000–9,500 B.C. 

Plains Archaic ........................................ 5,500–400 B.C. ..................................... 9,500 B.C.–A.D. 1 

Plains Woodland ..................................... 400 B.C.–A.D. 1850 ............................... 500 B.C.–A.D. 1000 

Plains Village ......................................... A.D. 1000–1850 ..................................... A.D. 900–1750 

Equestrian Nomadic ............................... Mid A.D. 1700–1851 ............................. N/A 

The following sections contain excerpts from the USACE CRMPs for Lake Oahe 

and Lake Sakakawea and is provided with the approval of USACE. These CRMPs 

are not accessible to the public in compliance with a Programmatic Agreement (PA) 

among the USACE and participating tribes to protect site location information. 

Therefore, the indented text in each section is provided as information to the reader 

that would not otherwise be available. 

Pre-Clovis 

Although no evidence exists for pre-Clovis occupation within the project area, the 

potential exists for the area to harbor deeply buried subsurface intact pre-Clovis evidence. The most convincing pre-Clovis evidence in North America may come from 

the Meadowcroft rock-shelter site in Pennsylvania (Adovasio et al. 1977, 1978, 

1980). Additional possible associated sites containing a pre-Clovis horizon are 

Pendejo Cave, New Mexico (Chrisman et al. 1996:357–376), Selby/Dutton and Lamb 

Springs, Colorado (Stanford 1979; Stanford et al. 1981), and the Big Eddy Site, Missouri (Ray 1997). While none of these sites are unequivocal, their existence lends 

credence to some oral tradition stories describing a gradual development in tool 

making as people adapted to their changing environment (USACE 2004b). 

Paleo-Indian 

The Paleo-Indian tradition is characterized by hunting and gathering adaptation, 

primarily of now extinct big game animals. Diagnostic artifacts or sites in North Dakota are typically attributed to the Clovis, Goshen, Folsom, Hell Gap-Agate Basin, 

Cody, Parallel Oblique Flaked, Pryor Stemmed, and Caribou Lake projectile points 

manufactured by the Paleo-Indian complexes. 

Sites identified as Clovis are generally kill sites and processing stations containing fossilized mega-fauna remains, but there have been a few campsites, quarry 

sites and base sites associated with Paleo-Indian occupation (Fiedel: 1987). Other 

Paleo-Indian sites in the West include the Anzick site, Montana (Lahren & 

Bonnichsen: 1974), and the Drake site, Colorado (Stanford: 1991). Evidence from 

Anzick suggests tool caches may be related to the burial practices of Clovis people. 

Clovis is the earliest recognizable culture complex—a complex which occurs repeatedly, in patterned and predictable contexts, in the Great Plains (Wood: 1980). 

Plains Archaic 

The Plains Archaic complexes recognized in North Dakota include Oxbow, 

McKean Lanceolate, Duncan, Hanna, Pelican Lake, and Yonkee as determined by 

the projectile point style. This tradition subsumes hunting and gathering adaptation 

to essentially modern flora and fauna. The atlatl was developed during this period 

and became the new hunting instrument of choice. The Plains Archaic people maintained a nomadic hunter/gatherer lifestyle and continued to hunt the larger mammals of the plains to include bison, elk, deer, and antelope. 

Early Archaic.—The Early Plains Archaic period is most commonly associated 

with the Folsom Complex whose significant diagnostic artifact is the Folsom deep 

fluted projectile point. In Lakota this point is identified as hist’o′la bla′h

ˆ a, ‘‘tapered 

without barbs’’ (Mesteth & Charging Eagle: 2000). Their tool technology was advanced and the archaeological evidence of early Folsom people consists of artifacts 

such as channel flakes, end scrapers, side scrapers, bifacial knives, burins, gravers, 

drill tools, choppers, ground stone abraders, bone awls, eye needles, tubular bone 

beads, and bone disks (Gunnerson: 1987). Folsom sites in this region are the Moe 

(Schneider: 1975), Lake Ilo and Winter sites (Haug: 1982) in North Dakota, and the 

Agate Basin (Frison & Stanford: 1982), Hell Gap (Irwin-Williams et al. 1973) and 

Carter Kerr/McGee Sites (Frison: 1984) in Wyoming. 
226 

Middle Archaic.—The Middle Archaic people continue to live as nomadic hunter/ 

gatherers, but climate conditions were changing and the last remaining megafauna 

in North America he’hˆ alo′g ̇eca iye ́ceca, ‘‘longhorn buffalo—Bison Antiquus’’ becomes 

extinct. This extinction forced people to alter their subsistence patterns and dependence upon smaller mammals, birds, fish, shellfish, and plants brought about a 

change in their tool making technology and their cultural development. Foraging for 

food plants takes on a greater importance during this period and archaeologists 

have become aware that foraging could be the basis for developing quite complex 

societies (Fiedel: 1987). 

As groups settled into more localized hunting territories an increased reliance 

upon local lithic resources occurred. The long thin lanceolate point tradition began 

to disappear and replacing them were side-notched projectile point types such as 

Hawken, Logan Creek, Oxbow, Bitterroot, Pahaska Side-notched, and Blackwater 

Side-notched points (Frison et al. 1996; Gregg et al. 1996). The use of local lithic 

material and more sparse use of exotic material in archaeological assemblages dated 

to this period seem to support this conclusion (Gregg et al. 1996; Fiedel: 1987). Modern bison remained the principle game for native people living across the Plains and 

this is demonstrated in the Hawken site in Wyoming (Frison et al. 1976), the HeadSmashed-In site (Reeves: 1978) in Alberta, Canada, the Smilden-Rostberg site (Larson & Penny: 1991) in North Dakota and the Granite Falls site (Dobbs & 

Christianson: 1991) in Minnesota. A number of habitation sites for this period have 

been discovered in the Big Horn Mountains of Wyoming, the Black Hills of South 

Dakota, and the Pryor Mountains of Montana. There are two important complexes 

identified in the Northern Plains for this period, Oxbow and McKean (Dahlberg and 

Whitehurst 1990:80; Frison et al. 1996). 

Terminal Archaic.—Terminal Archaic people are much more diverse culturally 

and linguistically. On the northern plains the Pelican Lake Complex manifests itself 

and spreads across Alberta, Saskatchewan, Manitoba, Montana, North and South 

Dakota, Idaho, Wyoming, Northern Colorado and Nebraska (Peterson et al. 1996). 

The diagnostic artifact is a thin, corner notched projectile point with wide, deepnotched corners or barbs on it (Frison: 1991). Sites attributed to Pelican Lake are 

the Head-Smashed-In (Reeves: 1978) site in Alberta Canada, and the Kobold (Davis 

& Stallcop: 1965) and Keaster (Frison: 1991) sites in Wyoming. Tool kits include 

scrapers, chisels, bifaces, choppers, drills and a variety of multi-purpose flake tools. 

The bone tool assemblage for Pelican Lake people consists of awls, beamers, hidegrainers, scrapers and antler tine flakers (Greg, et al. 1996). 

Known Archaic property types include animal kill sites, camps, Knife River flint 

quarry sites, lithic workshops, and burial sites (NDSHPO 2003). 

Plains Woodland 

The Plains Woodland culture continued the hunting and gathering adaptations, 

but can be characterized by increased sedentism, expansion of regional trade networks the practice of elaborate mound burials, production of ceramic vessels, and 

the intensified use of horticultural through indigenous seedy plants and grasses for 

supplemental food (Griffin 1967). During this period the bow and arrow replaced the 

atlatl at approximately A.D. 600. 

Early Plains Woodland.—The Early Plains Woodland period is generally associated with the development of ceramic technology (pottery), generally stone-tempered 

with cordmarked exteriors (Montet-White: 1968; Adair: 1996). The bow and arrow 

was introduced (Adair: 1996) replacing the throwing darts used by Archaic people. 

This period on the Dakotas is poorly understood and the Naze site (Gregg: 1987) 

was one of first to be excavated. The information from Naze and other sites in the 

region basically identifies Early Plains Woodland sites as seasonal use sites (Benn 

1990). Applicable traditions for this period describe the establishment of a distinct 

Dakota language cultural group inhabiting portions of the Ohio River valley. These 

Dakota speakers are the direct descendants of the Indian Knoll cultural group 

(Terrell: 1974). 

Middle Plains Woodland.—The Middle Plains Woodland is best characterized by 

the widespread manufacture of pottery, constructing permanent village sites, and 

the establishment of well-organized trade relations between different cultural 

groups specifically centered on the Hopewell culture. In the Midwest material resources and ornate objects were widely distributed as a result of these trading relationships and in Hopewell sites archaeologists have discovered obsidian from the 

Black Hills and Rockies, copper from the Great Lakes, shells from the Atlantic and 

Gulf coasts, mica from the Appalachians, silver from Canada, and alligator skulls 

from Florida (Waldman: 1985). Middle Plains Woodland people did have contact 

with Hopewellian people. Knife River flint artifacts have been found in a few Early 

and Middle Plains Woodland sites in Iowa (Benn: 1983). The location of Middle 
227 

Woodland sites suggests the gradual adaptation to more sedentary lifestyles. Settlement patterns among these people involved permanent to semi-permanent base 

camps typically situated at the base of bluffs or on side streams within the bluffs 

of large valleys (Fortier: 1984; Roper: 1979). 

Late Plains Woodland.—Late Plains Woodland is a time when mound building 

cultures faded out and people living in the Midwest began reverting to more nomadic, possibly less rigorously structured societies as major population centers were 

abandoned and people dispersed and spread out. There are important cultural 

changes taking place during this period that set the stage for the development of 

the Plains Village stage (Ford: 1977). Some noticeable changes are modification of 

ceramic technology and the development of an agricultural economy. An increase in 

the importance of maze is noted throughout the Midwest during this period (Ford: 

1977; Kelly 1984). Settlements were widely spread across the landscape and this 

was probably due to population growth. Habitation sites became more and more 

common above floodplain terraces along the Missouri River and its tributaries 

(Ludwickson et al. 1987). 

The North Dakota Plains Woodland complexes include Sonota/Besant, Laurel, 

Avonlea, Blackduck, Mortlach, Old Women’s, and Sandy Lake sites. Typical Plains 

Woodland property types include burial mounds and other burial sites, occupations, 

camps, quarries and lithic procurement areas, and bison kill sites (NDSHPO 2003). 

Plains Village 

The Plains Village tradition consisted of horticulturalists, as well as hunters and 

gatherers. The Plains villages dominated the North Dakota cultural scene from as 

early as A.D. 1000 until 1780 and included contact with European trappers and 

early settlers. Much of the later Plains Villages were decimated by the contraction 

of European diseases. One of the key elements in Plains Village adaptive strategies 

was the development of a dependable, storable surplus food supply primarily in the 

form of dried corn. Stored food facilities are indicative of the Plains Village period. 

The Plains Indian Village period is a time when the people inhabiting the Missouri River basin began establishing permanent village sites along the Missouri 

River and its tributaries. Plains village dwellers learned to plant the seeds traded 

to them from the Indians of the mound and temple building cultures in small garden plots they cultivated next to their villages. As people settle down and move farther and farther away from the nomadic lifestyles of their ancestors, they learned 

how to build earth lodges surrounded by protective wooden palisades or ditches. 

Gradually as villages grow larger in size small garden plots become tilled fields. Annual crops of corn, beans, squash, and sunflowers were raised and stored as winter 

food surpluses. Manufacturing pottery became wide spread among the tribes as they 

developed regional trading centers located throughout the plains. The Plains Village 

period may be divided into two variants, but both periods overlap each other and 

share cultural traits. The variants are the Middle Missouri Tradition (A.D. 900— 

A.D. 1200) and the Coalescent Tradition (A.D. 1200—A.D. 1740) (USACE 2006b). 

Middle Missouri Tradition.—Middle Missouri Tradition represents the first sedentary village occupations of the Missouri River and its tributaries occurring where 

agriculture becomes more important than bison hunting (Winham & Calabrese: 

1998:278). When corn was introduced tending to the crops during growing season 

forced people to remain in place for part of the year. This brought about a much 

more sedentary lifestyle that also required people to carefully choose a good location 

for establishing a village site where an ample supply of water, wild game, and wild 

plants could be easily obtained to sustain them until the crops were ready for harvesting (Zimmerman: 1985). Growing an abundance of crops allowed population levels to increase. Subsequently, when bands divided among themselves to occupy and 

settle new areas they could take their main food source with them. This meant that 

pottery became more important because it was used to store and cook the plants 

people are growing (Zimmerman: 1985). 

At the end of the period a variant complex within Middle Missouri called the Extended Middle Missouri Variant (EMM) began to appear. Sites attributed to the 

EMM are located along the Missouri River in the area of the Bad and Cheyenne 

Rivers, and are labeled as the Bad River phase (Winham & Calabrese: 1998). The 

Bad River phase is linked to the historic Arikara occupation of the area. Another 

variant complex, the Terminal Middle Missouri Variant (TMM), is believed directly 

related to EMM. The people of the TMM variant are considered ancestral to the 

Mandan (Johnson: 1996). 

Coalescent Tradition.—The Coalescent Tradition is best described as a time when 

massive population migrations were taking place. No one has ever been able to establish how the Coalescent Tradition developed; some claim the Middle Missouri 

Tradition people and Central Plains Tradition people basically joined together and 
228 

hence the term Coalescent. It is thought that people coming in gradually blended 

with groups already living along the Missouri River. Ceramics and lodges within the 

villages reflect this view as houses of the period were constructed in a square manner which is a trait associated with people from the Central Plains Tradition, and 

in a circular manner which is a trait associated with people from the Middle Missouri Tradition (Zimmerman: 1985). 

The Coalescent Tradition brought about the emergence of the Mandan, Cheyenne, 

Dakota, Arikara, Kiowa, Siouan Ponca, and Omaha tribes and traditions. 

The Mandan.—At a point probably towards the end of the period, a portion of the 

Miwa′t’a>ni began moving north up the Missouri River eventually reaching the 

mouth of the Little Missouri River where the group splits apart (Terrell: 1974). One 

group called Psa′loka, ‘‘Crow Indians,’’ moved southwest and settled in lands lying 

below the Rocky Mountains. The other group returned to the Knife River area and 

returning as they did the Miwa′t’a>ni begin calling them Mini′tari′, ‘‘Crossed the 

River.’’ The Mini′tari′ are historically identified as the Hidatsa. The Hidatsa and 

Crow kept their kin relation with each other and Crow trading parties helped the 

Hidatsa people establish numerous village sites in the Little Missouri and Yellowstone River valleys (Terrill: 1974). 

The Cheyenne.—One of the tribes sharing lands with the Dakota in Minnesota 

was the S ́ ahi′yela, ‘‘Red Talkers/Cheyenne Indians.’’ They are an Algonquian speaking people that migrated to the Minnesota River valley after abandoning their 

homelands above Lake Superior to the Chippewa (Grinnell: 1972) and established 

themselves along the Minnesota River and the Yellow Medicine River. Their earth 

lodge village at the Yellow Medicine River is called S ́ ahi′yela na wo′jupi, ‘‘Where the 

Cheyenne Plant’’ by the Dakota (Grinnell: 1972). When a war between the Chippewa and Dakota broke out the Cheyenne began a westward movement and ultimately abandoned their Minnesota and Yellow Medicine river village sites. Dakota 

traditions about the Cheyenne never indicate that warfare between the two tribes 

ever took place, but there are recordings attributed to Stephan Riggs, and Lewis 

and Clark, that indicate the Cheyenne were driven from the Minnesota River and 

the Yellow Medicine River valley by the Dakota and the Chippewa (Grinnell: 1972). 

One element of the Cheyenne eventually settled along the south bend of the 

Sheyenne River in the area of Lisbon, North Dakota (Grinnell: 1972). 

The Cheyenne villages in North Dakota were fortified and the people grew crops 

and hunted bison. Their lodges were circular in form with extended entryways usually facing southeast (Moore: 1996). The basic floor plan of the lodge was similar 

to the other lodges constructed by the Missouri River tribes. They were large circular structures enclosing a central fire pit and built around four central support 

posts (Grinnell: 1972). Other Cheyenne groups were nomadic hunters after leaving 

Minnesota. They hunted and traded with the Mandan and contrary to reports from 

Maximilian during the Missouri River travels who claimed the two tribes engaged 

in a war, the Cheyenne and Mandan people entered into and maintained friendly 

relations (Grinnell: 1972). In the last part of the 18th and in the early part of the 

19th century, the Cheyenne were dispersed over a wide territory extending from 

west of the Black Hills to the Missouri River, and from the Little Missouri River 

towards its mouth, and as far south as the Arkansas river (Grinnell: 1972). This 

wide dispersal was rewarding for the Mandan, Arikara, and the Ti′to>′wa> because 

the Cheyenne are the people that brought horses into the Northern Plains (USACE 

2004b). 

The Dakota.—Circa A.D. 1500 to A.D. 1600, the Dakota at Bde′ Waka>′ were engaging the Chippewa in a war for control of the marshy wild rice lands lying between the Lake of the Woods in Canada and Lake Superior and Lake Michigan. In 

the east the Iroquois began a period of territorial expansion and conquest that drove 

the Chippewa into the Dakota (Warren: 1984). The conflict between the tribes was 

a bloody one with each side winning and losing numerous battles. At the time of 

the war the Dakota were living as seven related bands, the Bde′ Waka>′to>′wa>, 

‘‘Spirit Lake Village People;’’ the Ti′to>′wa>, ‘‘Dwellers of the Plains;’’ the 

Sisi′to>wa>, ‘‘Slimy Ones;’’ the Wahˆpeto>wa>, ‘‘Leaf Village People;’’ the Wahˆpe′ 

kute, ‘‘Leaf Shooters;’’ the Iha>′kto>wa>′, ‘‘Camps on the End;’’ and the 

Iha>′kto>wa>la, ‘‘Little Camps on the End.’’ To hold their lands the Dakota formed 

an alliance known as the Oce′ti S ́ ako′wi>, ‘‘Seven Council Fires,’’ to defeat the Chippewa (Walker: 1982) and for a time they remained in control of the wild rice producing lands, but the formation of the alliance eventually impacted all of the tribes 

occupying the Missouri River (USACE 2004b). 

The Arikara.—Throughout the 17th century the Arikara continued to move up the 

Missouri River. The villages they constructed were earth lodges encircling a central 

plaza and typically there was a large ceremonial lodge facing the plaza area (Gilmore: 1930). Their lodges were circular structures containing central hearths and 
229 

large sub-floor cache pits. Many of the villages had fortified palisades or ditch entrenchments boarding them for protection (Ludwickson et al. 1987). Lakota and Dakota traditions describe the Arikara occupation of the Missouri River as expansive 

(LeBeau: 1994). Historically they may be known as traders, but to the Lakota they 

were a powerful enemy who were once considered relatives (Rice: 1994). They were 

the power in the Missouri River basin until massive epidemics of diseases ravaged 

and reduced their population after they came into contact with White people 

(USACE 2004b). 

The Kiowa.—The Kiowa are thought to have entered the Black Hills region circa 

1700 (Mayhill: 1971). They were a buffalo hunting people and never developed an 

earthlodge farming culture. They did establish trading relations with tribes in the 

area, primarily the Sc′ili, Pawnee and they often traveled along the Cheyenne and 

the Bad Rivers to trade with the Arikara. When the first Ogla′la and Sican′gu hunting bands entered the Black Hills country, the Kiowa began fighting with them over 

land and resources. A constant state of warfare between them and the Lakota continued until the late 1700’s when one of their sub-bands were wiped out near the 

headwaters of the Cheyenne River by a large Ogla′la war party (Mooney: 1898). 

This defeat forced the remaining Kiowa to leave the region and move south into the 

southern plains (USACE 2004). 

The Ponca and Omaha.—The Siouan Ponca and Omaha are thought to have entered the Missouri River region in the early part of the 18th century. Near the 

mouth of the White River they established a camp circa 1715 (Howard: 1995). The 

Ponca then moved on to the Black Hills and traded with the Kiowa for a time, but 

for unknown reasons they eventually migrated back to the White River camp and 

rejoined the Omaha. Both tribes followed the river back to the south, returning to 

the area around the mouth of the Niobrara River where they finally established a 

permanent presence (Howard: 1995). 

Typical Plains Village property types include occupations (fortified and unfortified 

earthlodge villages), winter villages, camps (hunting), flint quarries, eagle trapping 

sites and conical timber lodges, burials, lithic workshops, bison kill sites, and rock 

art sites (NDSHPO 2003). 

Equestrian Nomadic 

The Equestrian Nomadic tradition subsumes those lifeways that were dependent 

upon horses during protohistoric and early historic times in the Northern Plains. 

The introduction of the horse brought about significant changes in subsistence strategies, demographics, social organization, and settlement patterns. Known property 

types include camps, battle sites, and animal kill sites (NDSHPO 2003). 

3.2 Historic Period 

The Historic period on the Missouri River is defined as the period of first contact 

with non-Indians. During this period the Lakota were the preeminent power in the 

project area until they were removed, along with all of the tribes associated to the 

river basin area, to various reservations in North Dakota and South Dakota. The 

Historic Period consists of two parts: A.D. 1740 to 1804, the phase when the Lakota 

rise to power within the Missouri River basin and displace the Arikara, and A.D. 

1804 to 1890, the phase when Indians lose control of the land and are relocated to 

reservations. 

The first portion of the historic period represents a time when life along the Missouri River was in constant flux as the Lakota started crossing the river in the middle of the 17th century. The Arikara, the Mandan, and the Hidatsa have a wellestablished self-sufficient, surplus-abundant trading system operating throughout 

the Upper and Middle Missouri River region. The Mandan-Hidatsa villages below 

the Knife River in North Dakota were visited annually by the Cheyenne, Cree, 

Crow, Gros Ventre, and Yanktonai people who exchanged tanned buffalo, deer and 

elk hides for agricultural goods and material resources such as Knife River flint. 

The Arikara villages located at the mouth of the Grand, Cheyenne, Bad, and White 

Rivers were visited annually by the Cheyenne, Pawnee, Lakota and Dakota. The 

trade intercourse throughout the plains revolved around these trading centers and 

goods from the southwest, southeast, northwest, and northeast were traded regularly between the tribes (Bowers: 1950; Wood & Thiessen: 1985). 

By the 1790’s the Lakota were roaming over a vast hunting territory on both sides 

of the Missouri River as nomadic buffalo hunters. Traditions state that once the 

Ogla′la drove the Kiowa out of the Black Hills region the Lakota bands came together to hold a great council at Bear Butte. During this council they formed their 

own tribal alliance, which is also called the Oce′ti S ́ ako′wi>, ‘‘Seven Council Fires’’ 

(Plenty Chief: 1985). As the dominate power throughout the region, the Lakota and 

their Dakota cousins in Minnesota quickly gained control over a vast territory that 
230 

stretched to the Teton Mountains in the west, to the Minnesota River valley in the 

east. They maintained an almost constant state of warfare with the Pawnee, Shoshone, Crow, Blackfeet, Arikara, Mandan, Hidatsa, Cree and Plains Chippewa. By 

the turn of the century in 1800 the Lakota controlled all of the lands below the 

mouth of the Grand River that lie within the project area. The Ita′zipco and the 

Mniko′woju bands were occupying the area between the Bad and Cheyenne Rivers. 

The Hu>′kpapa were in the area between the Moreau and Grand Rivers, and the 

Siha′ Sa′pa and the Oo′henu>pa were in the area between the Cheyenne and 

Moreau Rivers (Hassrick: 1988). All along the Missouri River bottoms the various 

bands erected seasonal winter encampments, hunting camps and temporary trading 

camps where they traded with each other. The Lakota became regular visitors to 

the Big Bend area, holding councils with the Kul Wica′s ́a and Yankton bands who 

lived in the area. In the area around the Little Bend all of the Lakota bands, several Yankton bands, and various Sisseton and Santee Dakota bands held annual 

spiritual ceremonies and conducted individual spiritual activities on a regular basis 

(LeBeau: 1994; 2002). Farther up river in the area of Medicine Rock near the Little 

Cheyenne River, the Lakota visited the site for ceremonial purposes, but it is also 

considered an area where people could meet to trade with each other (LeBeau: 

1994). 

The first eyewitness report recording contact occurring between the Indians and 

non-Indians within the project area took place in 1743 when the Verendrye brothers, Chevalier and Louis, entered the area and traveled along the Cheyenne and Bel 

Fourche Rivers by canoe in an attempt to find an overland route to the Pacific 

Ocean (Chittenden: 1986). In March of that year they returned to the area of the 

mouth of the Bad River where they camped with a band of Arikara headed by Chief 

Little Cherry. On March 30, 1743 the Verendryes went to a hill at the junction of 

the Bad River with the Missouri and claimed the region for France, and planted a 

lead plate as evidence of the claim (Schuler: 1990). 

The second portion of the historic period consists of the interaction between the 

first non-native people and the local tribes as recorded by the early explorers, trappers, traders, military personnel, and settlers. 

In 1800 with the Louisiana Purchase the United States authorized a series of official U.S. Army expeditions to explore their newly acquired territory. In 1804 the 

Lewis and Clark Expedition entered the area seeking to discover a water route leading to the Pacific Ocean. The expedition sketched a map of the river attempting to 

list intersecting rivers, creeks, streams, and physical features such as prominent 

hills and buttes, Indian village sites, and expedition camping sites (USACE 2004b). 

In 1812 Fort Manuel was constructed along the west bank of the Missouri River, 

10 miles south of the present day North Dakota/South Dakota border (Schuler 

1990). The fort named after Manuel Lisa, a fur trader from St. Louis, was the first 

trading post operating within the project area. The fur trading business was booming and new forts were erected to meet the need for trading with the local tribes. 

The success of the fur trade operations along the upper Missouri created a need for 

additional manufactured good to be traded to the local tribes for furs. 

The establishment of the fur trade and the construction of trading posts in the 

project area helped open up the territory to settlement by homesteaders. By the 

time the fur trade was in full force the primary occupants of the territory were the 

Lakota and Dakota Indians (Schuler: 1990). Once the settlers began entering the 

region conflicts between them and the local native populations were inevitable. The 

Indian tribes wanted white trade goods, but they did not want the white settlers. 

Relations between the Indian tribes, specifically the Lakota and Dakota, and the 

United States began deteriorating in the late 1820’s and early 1830’s. 

Due to the influx of outsiders to the region new diseases spread among the tribes 

decimating their populations. In 1837 a smallpox outbreak on the Northern Plains 

reduced the Indian population by half including seven-eighths of the Mandan and 

over 50 percent of the Arikara populations (Dollar 1977). These disease outbreaks 

greatly reduced the fur trade with the local indigenous people. 

To secure trading rights with various Indian tribes the United States Government 

began making treaties with the tribes as the westward expansion into the Northern 

Plains took place. Invariably the treaty processes also attempted to establish territorial limits for individual Indian tribes and get them to acknowledge that the 

United States had supremacy over them. Stipulations to protect the tribes from depredations committed upon them by non-Indians not legally authorized to enter their 

country for the purposes of trade or other views were also included in the treaties 

that were made during this period. By the 1850’s government treaties with the 

tribes in the Great Plains began including additional language that dealt with the 

right of the United States Government to establish roads, military and other posts 

within a tribe’s respective territory, as well as delineate a set boundary for that ter-
231 

ritory (LeBeau: 1997). The United States failed to maintain its treaty obligations 

with the tribes to keep non-Indians out of Indian land and this failure more than 

any other factor is what caused conflicts to break out that eventually resulted in 

the Missouri River tribes being removed to permanent Indian reservations (LeBeau: 

1997). 

In 1851 the first Treaty of Fort Laramie was made by the United States Government with the Sioux, Cheyenne, Arapaho, Crow, Assiniboine, Gros Ventre, Mandan 

and Arikara tribes. This was an important event because this treaty impacted all 

of the Indian tribes who resided in the Missouri River basin running through the 

Dakotas. Under Article 5 in the treaty, physical boundaries delineating the territories of each tribe are described and these physical descriptions provide indications 

where tribal populations were located in 1851. In 1868 as a result of Red Clouds 

War, a second Fort Laramie Treaty was made with the Sioux, which established the 

Great Sioux Reservation and delineated its physical boundaries. Again the descriptions provide an indication of where tribal populations were located. 

It was not just treaties the United States Government entered into with Indian 

tribes living along the Missouri River. Agreements between the Government and Indian tribes were also made, and in 1866 the United States made the Fort Berthold 

Agreement with the Arikara, Mandan and Hidatsa, which ceded land to the Government. In 1882–1883 the Agreement with the Sioux of Various Tribes was made, and 

this agreement broke up the Great Sioux Reservation and established 5 separate 

reservations for the Sioux; those are Pine Ridge, Rosebud, Standing Rock, Cheyenne 

River, and Lower Brule (USACE 2004). 

The first military post in the region, Fort Pierre, was purchased by the U.S. Army 

in 1855, but later abandoned in 1857 due to lack of surrounding resources. In 1863 

a second military installation, Fort Sully, was established along the left bank of the 

Missouri River, 6 miles below Pierre, South Dakota. Fort Sully served as headquarters for military troops stationed in the area, but was abandoned in 1866 and 

relocated 34 miles upstream of the Missouri River approximately 30 miles below the 

confluence with the Cheyenne River (Frazer 1965). Several additional military installations sprang up along the Plains of the Missouri River drainages over the next 

few decades to include Fort Rice in 1864, Fort Bennett in 1870, Fort Abraham Lincoln in 1872, and Fort Yates in 1874 which remained a military post until 1903 

(Frazer 1965). 

In order to supply the military installations and trading posts, steamboats were 

used to navigate the Missouri River. The steamboat era was one of booming commerce, with many ships plying the major rivers of the West. Steam operated wheel 

boats were used on the Missouri River as early as late 1850s. By 1859 steamboats 

started to visit Fort Benton on a regular basis. During the 1850s, Government contracts were issued to companies willing to navigate the Missouri River to deliver annuities to various Indian Tribes as required by treaty (Chittenden 1936; Schuler 

1990). 

Steamboat travel was risky and dangerous since many of the inland rivers were 

shallow during the summer, fall, and winter months. Paddle wheelers were subject 

to accidents that could damage a cargo or destroy the vessel. The Missouri River 

was especially dangerous due to its shallow waters, swift currents, and narrow navigable channel. Many paddle steamers perched their paddle-wheels on submerged 

sand bars, often stranding the ship until high water returned the following spring. 

In addition to the sandbars, numerous dead trees and snags washed down stream 

within the channel and could puncture the bottom of boats. By 1897 over 295 steamboat wrecks were recorded along the Missouri River corridor; 193 of these wrecks 

were caused by dead trees and snags (Chittenden 1897). Chittenden reports 11 

steamboat wrecks occurred along the North Dakota segment of the Missouri River 

alone (Table 3–2). 

TABLE 3–2.—SHIP WRECKS ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Name of Ship Year of Wreck Location of Wreck 

Abner O’Neal ............................................................................................ 1892 Painted Woods, North Dakota 

Amelia Poe ............................................................................................... 1868 Near Little Porcupine Creek 

Assinniboine ............................................................................................. 1835 Head of Sibley Island, North Dakota 

Behan ....................................................................................................... 1884 Bismarck, North Dakota 

Black Hills ................................................................................................ 1884 Bismarck, North Dakota 

Colonel McCloud ....................................................................................... 1879 Bismarck, North Dakota 

Denver No. 2 ............................................................................................ 1880 Fort Lincoln, North Dakota 

Emily No. 3 ............................................................................................... 1885 North of Bismarck, North Dakota 

Ida Stockdale ........................................................................................... 1871 Bismarck, North Dakota 
232 

TABLE 3–2.—SHIP WRECKS ALONG THE MISSOURI RIVER IN NORTH DAKOTA—Continued 

Name of Ship Year of Wreck Location of Wreck 

Island City ................................................................................................ 1864 Below Fort Buford, North Dakota 

Rose Bud .................................................................................................. 1896 Bismarck, North Dakota 

Source: Captain H. M. Chittenden’s Report of the Chief of Engineers, U.S. Army (1897). 

By the mid 1880s, steamboat traffic ceased to exist. The completion of the transcontinental railroad and subsequent railroad branches replaced river traffic. 

The early pioneer settlement of the Dakotas was directly influenced by the construction of the railroads. The Dakota Central branch of the Chicago & North Western Railroad built a track from Tracy, Minnesota to Pierre, South Dakota during 

1879 and 1880. In the 1880s during the Great Dakota Boom (Robinson 1974) emigrants from Norway, Germany, Russia, along with Midwestern groups in the United 

States, flooded into Dakota Territory and the non-Indian population exploded with 

these settlers coming in (USACE 2004b). New towns, farms, and rail lines cropped 

up. The State’s main economic base was primarily tied to agriculture. 

The last major event to occur that directly impacted the Native and non-Native 

population living along the Missouri River was the construction of the Pick-Sloan 

Reservoirs. The contemporary Missouri River in North Dakota is highly modified 

from its natural character due to the Flood Control Act of 1944. The Flood Control 

Act was Federal legislation that led to the establishment of the Pick-Sloan Plan to 

construct six large dams on the Missouri River main stem from Nebraska to Montana. Closure of the Garrison Dam in 1953 and the Oahe Dam in 1958 and flooding 

the river bottom displaced thousands of people from their homes. The cultural effects on the people that lived on the river have never been adequately researched 

(LeBeau 1994). 

Some of the historical and cultural sites that are open to tourists include Fort 

Union Trading Post National Historic Site, Fort Buford State Historic Site, Knife 

River Indian Villages National Historic Site, Fort Clark State Historic Site, Double 

Ditch Indian Village State Historic Site, and On-A-Slant Indian Village State Historic Site. 

4.0 RESOURCE EVALUATION 

4.1 Site Types and Known Resources 

Berger assessed the potential types of cultural resources within Burleigh, 

Emmons, Mclean, Morton, Oliver, Williams, Dunn, McKenzie, Mercer, Mountrail, 

and Sioux Counties. The areas included USACE jurisdiction areas at Lake Oahe 

and Lake Sakakawea, the Standing Rock Sioux and Fort Berthold Reservations, as 

well as designated aggregation areas of the Missouri River corridor. File searches 

were conducted by USACE. File searches for private land along the main stem near 

the town of Washburn were conducted through the State Historical Society of North 

Dakota between January and March 2009. The list of legal locations encompassed 

by the files and literature search is included in Exhibit 1. 

It should be noted that, while previous investigations have been conducted, there 

are portions of the project area where no surveys have been completed, particularly 

on private or tribal lands. Site types encountered during the records search include 

prehistoric sites, historic sites, multi-component sites (sites with both prehistoric 

and historic materials), and sites that cannot be assigned to a specific time period 

(‘‘unknown’’). 

The research conducted by USACE revealed that prior investigations have been 

undertaken within the aggradation areas; 148 sites have been recorded within the 

Lake Oahe portion of the project area, and 1,216 sites have been previously recorded 

within the Lake Sakakawea portion of the project area. The sites at Lake Oahe consist of 90 prehistoric, 31 historic, 17 multi-component, and 10 unknown sites. The 

sites at Lake Sakakawea consist of 835 prehistoric, 120 historic, 54 multi-component, 246 paleontological, and 205 unknown sites. The site information for Lake 

Oahe is summarized in Table 4-1. The site information for Lake Sakakawea is summarized in Table 4–2. To assist the reader, a glossary of common archaeological 

terms in included in Exhibit 2. 

TABLE 4–1.—SITE TYPES WITH U.S. ARMY CORPS OF ENGINEERS JURISDICTION AT LAKE OAHE 

Site Type Historic Prehistoric Unknown Number 

Artifact Scatter ............................................................. ........................ ........................ X 32 

Buffalo Jump ................................................................ ........................ X ........................ 1
233 

TABLE 4–1.—SITE TYPES WITH U.S. ARMY CORPS OF ENGINEERS JURISDICTION AT LAKE OAHE— 

Continued 

Site Type Historic Prehistoric Unknown Number 

Grave Sites ................................................................... ........................ X X 2 

Buried Bone Bed ........................................................... ........................ X ........................ 3 

Camp/Ceramic Site ....................................................... ........................ X ........................ 1 

Dam ............................................................................... X ........................ ........................ 1 

Dugout ........................................................................... X ........................ ........................ 1 

Earthlodge Village ........................................................ ........................ X ........................ 42 

Hearth/Lodge ................................................................. ........................ X ........................ 13 

Homestead .................................................................... X ........................ ........................ 19 

Military Post .................................................................. X ........................ ........................ 2 

Mounds ......................................................................... ........................ X ........................ 9 

Rock Cairns .................................................................. ........................ ........................ X 1 

Town site ...................................................................... ........................ X ........................ 1 

Community Center ........................................................ X ........................ ........................ 1 

Unknown ....................................................................... ........................ ........................ X 15 

TOTAL ............................................................... ........................ ........................ ........................ 144 

Of the 144 sites recorded at Lake Oahe, 123 sites are eligible for inclusion in the 

National Register, and 21 sites remain unevaluated for eligibility for the National 

Register. 

TABLE 4–2.—SITE TYPES WITH U.S. ARMY CORPS OF ENGINEERS JURISDICTION AT LAKE 

SAKAKAWEA 

Site Type Historic Prehistoric Unknown Number 

Artifact Scatter ............................................................. X X X 187 

Buffalo Jump ................................................................ ........................ X ........................ 3

Grave/Burial Sites ......................................................... X X X 18 

Buried Bone Bed ........................................................... ........................ X ........................ 2 

Camp/Ceramic Site ....................................................... ........................ X ........................ 2 

Bridge ............................................................................ X ........................ ........................ 2 

Dugout ........................................................................... X ........................ ........................ 39 

Earthlodge Village ........................................................ ........................ X ........................ 14 

Hearth/Lodge ................................................................. ........................ X ........................ 2 

Homestead .................................................................... X ........................ ........................ 46 

Military Post .................................................................. X ........................ ........................ 2 

Mounds ......................................................................... ........................ X ........................ 2 

Rock Cairns .................................................................. ........................ X X 160 

Town site ...................................................................... ........................ X ........................ 8 

Community Center ........................................................ X ........................ ........................ 1 

Cemetery ....................................................................... X ........................ ........................ 13 

Ceramic/Lithic Scatter .................................................. ........................ X ........................ 8 

Church ........................................................................... X ........................ ........................ 1 

Eagle Trap .................................................................... ........................ X ........................ 31 

Quarry/mine .................................................................. X ........................ ........................ 4 

Trail ............................................................................... X ........................ ........................ 1 

Indian Agency ............................................................... X ........................ ........................ 1

Isolated Finds ............................................................... ........................ ........................ X 71 

Lithic Scatter ................................................................ ........................ X ........................ 249 

Mission .......................................................................... X ........................ ........................ 1 

Paleontological Localities ............................................. ........................ ........................ ........................ 246 

Post Office .................................................................... X ........................ ........................ 1 

Railroad Roundhouse Grade ......................................... X ........................ ........................ 1 

Ranch ............................................................................ X ........................ ........................ 3 

Sacred Object ............................................................... ........................ X ........................ 1

School ............................................................................ X ........................ ........................ 3 

Stone Circles ................................................................. ........................ X ........................ 200 

Stone Alignments .......................................................... ........................ X ........................ 12 

Teepee Rings ................................................................ ........................ X ........................ 52 

Trading Posts ................................................................ X ........................ ........................ 3 

Unknown ....................................................................... ........................ ........................ X 70 
234 

TABLE 4–2.—SITE TYPES WITH U.S. ARMY CORPS OF ENGINEERS JURISDICTION AT LAKE 

SAKAKAWEA—Continued 

Site Type Historic Prehistoric Unknown Number 

TOTAL ............................................................... ........................ ........................ ........................ 1,460 

Of all sites recorded at Lake Sakakawea, the number of sites eligible for inclusion 

in the National Register is 22. The number of sites unevaluated for inclusion in the 

National Register is 1,194. (Paleontological localities are not included in the numbers.) 

The Three Affiliated Tribes (Mandan, Arikara, Hidatsa) at the Fort Berthold Reservation currently does not maintain a database of sites that could be searched. 

Therefore, there are no numbers available to add to the site types. 

The research conducted by the NDSHPO revealed that more than 70 sites have 

been previously recorded on private land portions subject to aggradation along the 

main stem of the river within the project area. This information is summarized in 

Table 4–3 below. 

TABLE 4–3.—SITE TYPES PREVIOUSLY LOCATED WITHIN AGGRADATION AREAS ON PRIVATE LAND 

Site Type Historic Prehistoric Unknown Number 

Post Office .................................................................... X ........................ ........................ 4 

School ............................................................................ X ........................ ........................ 2 

Church ........................................................................... X ........................ ........................ 2 

Farmstead ..................................................................... X ........................ ........................ 11 

Unknown Foundation .................................................... X ........................ ........................ 1 

Unknown ....................................................................... ........................ ........................ X 4 

Trading Post ................................................................. X ........................ ........................ 1 

Artifact (Trash) Scatter ................................................ X ........................ ........................ 4 

Pump House .................................................................. X ........................ ........................ 1

Bridge ............................................................................ X ........................ ........................ 6 

Coal Mine ...................................................................... X ........................ ........................ 1 

Stone Circles ................................................................. ........................ X ........................ 5

Earthlodge Villages ....................................................... ........................ X ........................ 5 

Burials ........................................................................... ........................ X ........................ 3 

Artifact Scatters ........................................................... ........................ X ........................ 26 

TOTAL ............................................................... ........................ ........................ ........................ 76 

Of the 76 sites, 4 sites are eligible for inclusion in the National Register; 4 sites 

are ineligible for inclusion in the National Register; and 68 sites are unevaluated. 

The NDSHPO lists 32 historic period context themes in the Statewide Comprehensive Plan (NDSHPO 2003). Of the 32, at least 24 are pertinent to projects 

that could be conducted by USACE to address siltation and erosion, as well as other 

projects, along the Missouri River. Historic site types, as defined by the NDSHPO 

(2003) that could be encountered are: —Bridges.—Relates to historical and/or design, engineering and/or architectural 

values of bridges, grade separations, and trestles. —Colonization.—Relates to the planned and organized immigration, settlement 

and/or resettlement of groups to, into, or within North Dakota from other areas. 

Groups may be religious, social, ethnic, or others, such as a Hutterite colony. 

Typical property types may include: towns, colonies, settlements, reservations, 

businesses, residences, and farms. —Commerce.—Relates to the establishment, growth, and operations of the sale or 

exchange of goods, including banking and financial support services. Typical 

property types may include: trading posts, retail stores, wholesale stores, general stores, banks, savings and loan institutions, brokerage houses, mail order 

houses, shipping and transportation facilities, and the homes of prominent merchants, bankers. —Communications.—Relates to the transmission of messages and information. 

Typical property types may include: pow wow sites, traditional cultural properties, newspaper offices, telegraph and telephone facilities, post offices and 

mail stations, post roads, radio, T.V. and microwave stations and towers. 

—Depression—The Great.—Relates to the causes, effects of, conditions during, 

and/or relief and recovery from the Great Depression, 1929–1940. Typical property types may include: abandoned farms, banks, business buildings, city parks, 
235 

civic improvements, relief facilities, WPA projects, Civilian Conservation Corps 

(CCC) camps and project sites. —Education.—Relates to the organized transmission of formal knowledge, training and skills. Typical property types may include: schools, boarding schools, 

colleges, universities, business schools, trade schools, campuses, campus living 

quarters, administration buildings, and homes of prominent educators. —Energy Development.—Relates to the establishment, development and use of 

mechanical, hydro- and electrical power sources, their generation, distribution 

and use. Typical property types may include: water wheels, steam and/or electrical generating and transmission facilities, dams, and power stations. This 

context should not include coal or petroleum production facilities. —Exploration.—Relates to the exploration, discovery, recording and dissemination 

of information about the characteristics, attributes, and values of the State. 

Typical property types may include: trails, camp sites, camps, forts, battlefields, 

storage yards, and the residences of prominent explorers. —Farming.—Relates to the establishment and operation of farms. Typical property types may include single or multiple dwellings, barns, corrals, privies, 

dumps, grain storage, animal shelters, indoor and outdoor storage facilities, and 

water sources. —Fur Trade.—Relates to the establishment, operation and adaptations of the fur 

trade industry in North Dakota, particularly (although not exclusively) from the 

late 18th to the late 19th centuries. Typical property types may include, fur 

trading posts and forts, trails, loading and shipping facilities, trapping, trading 

and hunting grounds, camps and camp sites, steamboat docks, stores, dwellings, 

warehouses, and residences of prominent fur trade participants. —Government—National.—Relates to the establishment and operation of U.S. authority over, control of, and services to the area within North Dakota’s current 

boundaries. Typical property types will generally include: Federal Government 

office buildings, Federal courthouses, border stations, reservation headquarters, 

customs houses, and post offices, but may also occasionally include: mail stations, forts, trails, roads, highways, camps, camp sites, and dwellings. —Irrigation and Conservation.—Relates to the conservation and planned use of 

land and water resources. Typical property types may include: historically significant shelter belts, conservation-oriented farming sites, pumping stations, 

water pipelines, dams, reservoirs, canals, and flumes. —Military.—Relates to all aspects of the military presence in the State. Typical 

property types may include: forts, cantonments, posts, Air Force installations, 

armories, battlefields, trails, roads, bridges, fords, mail stations, cemeteries, villages, camps, camp sites, dumps, defensive works, corrals, barns, storage areas, 

and dwellings and residences. —Railroads.—Relates to the establishment and operation of the railroad industry 

in North Dakota. Typical property types may include: railroad grades, bridges 

and trestles, depots, freight yards, switch yards, barracks, dormitories, construction yards, section houses, roundhouses, loading facilities, construction camps, 

trails, camps, camp sites, office buildings, warehouses, dumps, and signal devices. 

—Ranching—Fee Simple.—Although similar to ‘‘Open Range Ranching’’ in general 

activities and products, important differences separate this context from the 

other. Fee Simple Ranching is characterized by the widespread use of privately 

owned, fenced land. Usually intended to be permanent occupants of limited 

space, these ranches were oriented towards continual re-use of the natural resources, perpetuation and improvement of smaller herds, were usually locally 

owned and financed, tended to operate on a smaller scale and remain a part 

of the State’s agricultural economy. Typical property types may include: single 

and multiple unit dwellings, barns, corrals, feed lots, equipment storage yards 

and buildings, and wells. 

—Religion.—Relates to the establishment and operations of religious groups and 

institutions. Typical property types may include: colonies, traditional cultural 

properties, shrines, holy places, churches, synagogues, rectories, parsonages, 

church schools and colleges, convents, and monasteries. 

—Roads, Trails, and Highways.—Relates to the development and use of overland 

transportation systems (excluding railroads) including trails, roads, highways, 

automobile and truck traffic, stagecoach and bus traffic and wagon routes. Typical property types may include: trails, historically significant roads and highways, bridges, fords, stage stations, rest stops, auto dealerships, gasoline stations, freight yards, barns, relay stations, maintenance shops, dwellings, repair 

shops, bus depots, bus barns, and possibly camps, campsites, motels, inns, and 

diners. 
236 

—Rural Settlement.—Relates to factors that influenced (or were influenced by) 

settlement in rural areas including rural institutions, rural industries (except 

farming and ranching), ethnicity, colonization, and social institutions. Typical 

property types may include: churches, factories, assembly plants, brick making 

factories, roads-trails-highways, fords, ferries, and river crossings, cemeteries, 

social gathering places, rural schools, township halls, mills, forts, and railroad 

properties. —Water Navigation.—Relates to the commercial use of North Dakota’s lakes and 

rivers for transportation of goods and people. While focusing on the steamboat 

industry, the context is intended to include other forms of commercial water 

navigation, but to generally exclude recreational boating. Typical property types 

may include: steamboat docks, wharfs, piers, wood yards, ferries, storage yards, 

freight yards, loading facilities, wrecks or wreckage, boatyards, and dry docks. 

5.0 DESCRIPTION OF IMPACTS 

5.1 Current Land Use 

The jurisdictional boundary of USACE is considered the shoreline along Lake 

Oahe and Lake Sakakawea shown in Figure 1–1. The land use around the reservoirs is primarily for USACE operations and maintenance and public recreation. 

Between the two reservoirs is private and tribal land. The land uses on the most 

of that reach of the river is agricultural, ranching, recreation, and some community 

facilities (e.g., Washburn). 

5.2 Sources and Deposit Locations of Erosion and Sedimentation 

For purposes of this assessment, the main stem of the Missouri River is divided 

into four segments, each of which has the potential to be affected by sedimentation 

and subsequent erosion. From north to south, the segments are described below. 

Williston Reach 

The Missouri River between the Montana border and the upstream end of Lake 

Sakakawea is generally referred to as the Williston reach. This approximately 60- 

mile section of the Missouri River is not inundated by a reservoir and the confluence 

with the Yellowstone River is within this reach. When this sediment load meets the 

slow-moving headwaters of Lake Sakakawea, it settles out and forms a delta. 

Lake Sakakawea 

Lake Sakakawea is a reservoir of approximately 286 kilometers in length (Galat 

et al., 1996). It has a delta that is 61 kilometers in length, formed by the deposition 

of sediment from the Williston reach (Galat et al. 2005). Sakakawea’s waters are 

colder, clearer, deeper, and more hydrologically stable than what they would have 

been prior to the construction of the dam. 

Garrison Reach 

Aside from the Williston reach, the Garrison reach, is the only other section of 

the river in North Dakota that is not inundated by a reservoir. However, this approximately 80-mile reach is controlled by releases from Garrison Dam. The Garrison reach between Garrison Dam and the headwaters of Lake Oahe is relatively deprived of sediment because of the retention of sediment in Lake Sakakawea. Major 

sources of sediment in this reach come from tributaries, not from the upstream segments; among these tributaries, the Heart River is the most important contributor 

of sediment (MacekRowland 2000). 

Lake Oahe 

Lake Oahe, formed by the Oahe Dam in South Dakota, is the longest of the six 

Pick-Sloan Reservoirs, 372 kilometers in length (Galat et al. 1996). Sediment import 

from the Garrison reach forms a delta 103 kilometers in length (Galat et al. 2005). 

Only a third of Lake Oahe is located within North Dakota, with the remainder in 

South Dakota. Recent drought conditions have changed the upstream reservoir sections from flat water (typically at elevations above 1,600 to 1,608 feet msl) to 

riverine characteristics that could affect cultural resource sites that are exposed 

from falling water levels. 

In the Identification of Sources and Deposits and Locations of Erosion and Sedimentation report prepared for the USACE, Berger (2008) found that: 

—The majority of the identified aggradation areas were located upstream of Lake 

Sakakawea in the close vicinity to the Montana/North Dakota border and in the 

vicinity of watersheds that showed large amounts of delivered land-based sediments. It appears that the largest delivered sediment load originates from Montana. The area between Garrison Dam and Lake Oahe showed only one 

aggradation area. Potential sources for sediment deposition were sediment ero-
237 

sion from upstream and surrounding watersheds that have high potential of delivering sediments. 

—Areas that showed little or no aggradation were generally located within the 

center of lakes (Lake Sakakawea and Lake Oahe), the majority of the section 

between Garrison Dam and Lake Oahe, and in the vicinity of watersheds that 

delivered considerable less sediment. 

5.3 Impacts on Indian and Non-Indian Sites 

According to USACE and NDSHPO records of known Indian and non-Indian sites 

along the reservoirs and main stem of the river within potential areas of 

aggradation and erosion, USACE and other researchers have recorded erosion, inundation, bioturbation, and effects of farming, construction, and vandalism. Table lists 

observations of impacts at Lake Oahe, and Table lists observations at Lake 

Sakakawea. 

TABLE 5–1.—IMPACTS OCCURRING ON SITES AT LAKE OAHE 

Impacts Number of Sites Impacted 

Cut bank Erosion ................................................................................................................................................. 34 

Unspecified Erosion .............................................................................................................................................. 7 

Shoreline Erosion .................................................................................................................................................. 7 

Complete Inundation ............................................................................................................................................ 10 

Partial Inundation ................................................................................................................................................ 7 

Periodic Inundation .............................................................................................................................................. 8 

Decay/weathering ................................................................................................................................................. 2 

Razed .................................................................................................................................................................... 10 

Cultivation ............................................................................................................................................................ 22 

Bioturbation .......................................................................................................................................................... 1 

Recreation ............................................................................................................................................................ 2 

Railroad Construction .......................................................................................................................................... 2 

Vandalism/unauthorized Collection ...................................................................................................................... 3 

Vehicular Movement ............................................................................................................................................. 8 

Unknown ............................................................................................................................................................... 7 

TOTAL ...................................................................................................................................................... 130 

TABLE 5–2.—IMPACTS OCCURRING ON SITES AT LAKE SAKAKAWEA 

Impacts Number of Sites 

Impacted 

Cut bank Erosion ................................................................................................................................................. 74 

Unspecified Erosion .............................................................................................................................................. 111 

Shoreline Erosion .................................................................................................................................................. 108 

Complete Inundation ............................................................................................................................................ 85 

Partial Inundation ................................................................................................................................................ 8 

Periodic Inundation .............................................................................................................................................. 12 

Siltation/buried ..................................................................................................................................................... 59 

General Disturbance ............................................................................................................................................. 19 

Absent .................................................................................................................................................................. 139 

Authorized Archaeological Collection ................................................................................................................... 22 

Grazing ................................................................................................................................................................. 51 

Deflation ............................................................................................................................................................... 8 

Development ......................................................................................................................................................... 1 

Decay/weathering ................................................................................................................................................. 29 

Razed .................................................................................................................................................................... 14 

Cultivation ............................................................................................................................................................ 68 

Landscape Construction ....................................................................................................................................... 11 

Military Activity .................................................................................................................................................... 7 

Moved ................................................................................................................................................................... 3 

Overgrown ............................................................................................................................................................. 23 

Bioturbation .......................................................................................................................................................... 24 

Recreation ............................................................................................................................................................ 95 

Railroad Construction .......................................................................................................................................... 15 

Vandalism/Unauthorized Collection ..................................................................................................................... 13 

Vehicular Movement ............................................................................................................................................. 83 
238 

TABLE 5–2.—IMPACTS OCCURRING ON SITES AT LAKE SAKAKAWEA—Continued 

Impacts Number of Sites 

Impacted 

Other ..................................................................................................................................................................... 28 

Unknown ............................................................................................................................................................... 93 

TOTAL ...................................................................................................................................................... 1,203 

Natural or human-caused impacts to Indian and non-Indian sites can be direct or 

indirect. 

Direct Impacts.—Those impacts that would be caused by deposition of silt and 

sediment, flooding, erosion caused by waves or changes in reservoir levels, and 

ground surface disturbance during construction projects associated with siltation remediation (such as rip-rap placement). 

Indirect Impacts.—Those impacts that would be caused by factors associated with 

increased agency, tribal, or public access to site locations. These could include inadvertent ground disturbance, vandalism, or changes to the viewshed. 

Several studies of the effects of reservoir construction and inundation of cultural 

resources have been conducted (e.g., Carrell et al. 1976; Adivasio 1980; Lenihan et 

al. 1981a, 1981b; Fairley 2003). There are four basic reservoir areas that are important to understanding effects to cultural resources (USACE 2002): (1) The Inundation Zone—the main body of water making up a reservoir excluding its lateral 

edges; (2) Zone of Fluctuation—the reservoir area where water levels range between 

high water to low water marks and includes land not always under water; (3) Zone 

of Direct Impact—the reservoir area where cultural resources are located and potentially in contact with water levels; and (4) Zone of Indirect Impact—the land adjacent to a reservoir that is not exposed to inundation. 

The impacts of siltation and erosion on cultural resources occur in the Inundation 

Zone, Zone of Fluctuation, and Zone of Direct Impact, while (as expected) indirect 

impacts occur most frequently in the Zone of Indirect Impact. 

While siltation can effectively and beneficially protect and preserve some sites, 

such as subsurface archaeological sites, often the subsequent wind or water erosion 

is destructive. Recent drought conditions have resulted in lower than normal lake 

levels in Lake Oahe changing the upstream character of the reservoir from a reservoir to that of riverine character. Of particular concern is cut bank erosion. Archaeological sites and historic structures along reservoir and river banks can slowly 

or drastically erode away as the shoreline erodes. Indian and other ethnic group traditional use or ceremonial areas, also known as TCPs, can be affected by both siltation (covering the resource or area) and erosion (depleting the resource or area). 

Other factors potentially destructive to cultural resources are agricultural and grazing leases close to the USACE jurisdictional boundary (Gilbert personal communication 2009). Because Indian and non-Indian sites resources are non-renewable resources, almost all impacts as a result of siltation and erosion are considered adverse or negative. In cultural resource terms, the integrity, or composition and cohesiveness, of a site is crucial to a site’s significance and intrinsic value to understanding our history or prehistory. The magnitude of the impact to the integrity of 

a site can vary from minor (e.g., artifact displacement resulting from sediment 

movement) to substantial (e.g., complete removal of a stone circle, stone cairn, or 

structural foundation resulting from an erosion event). 

6.0 SUMMARY AND RECOMMENDATIONS 

Cultural resources are considered a non-renewable resource that can be lost forever when destroyed. For Indian and non-Indian historical and cultural sites, the 

primary recommendation is to provide mitigation of impacts resulting from the cycle 

of siltation and erosion. Mitigation is defined as avoiding or lessening impacts to 

significant resources. Mitigation measures for the types of adverse impacts listed in 

Section 5.3 can range from cultural resource inventories, to regular periodic monitoring of known sites, to full-scale excavation and data recovery. Measures to be 

taken would depend on the type, context, character, setting, size, complexity, and 

other characteristics of the individual resources. Cultural resource inventory 

projects identifying surface sites, features, and standing structures are usually considered short-term measures, although pedestrian surveys may need to be repeated 

as environmental or site conditions change over time. Other more long-term measures can consist of fencing for avoidance, monitoring during ground-disturbing activities, and stabilization of stream banks or building foundations. 
239 

Long-term, periodic monitoring of the condition of surface and subsurface cultural 

resources should be done by prehistoric or historical archeologists. Monitoring of 

standing structures should be done by architectural historians. Should full-scale excavation be needed to retrieve scientific data that are in danger of being lost from 

development or fluctuation of water levels, the duration would depend on the surface extent and depth of the cultural material; in other words, how big is the site 

and how deep does it extend below the ground surface? This would be considered 

a short-term project compared to monitoring. All work should be performed by specialists whose credentials meet or exceed the Secretary of Interior’s Professional 

Qualifications Standards. 

Table 6–1 and Table 6–2 list future actions and mitigation measures recommended in the USACE site database for known Indian and non-Indian sites at 

Lake Oahe and Lake Sakakawea. 

TABLE 6–1.—RECOMMENDATIONS BY THE U.S. ARMY CORPS OF ENGINEERS AT LAKE OAHE 

Recommendation Number of Sites 

Monitor at Low Water Levels ............................................................................................................................... 4 

More Research Required ...................................................................................................................................... 1 

Test for NRHP Eligibility ...................................................................................................................................... 62 

Re-evaluate Site ................................................................................................................................................... 9 

No Further Work Needed—Completely Inundated ............................................................................................... 10 

No Recommendation Available ............................................................................................................................ 18 

Other (Unspecified) .............................................................................................................................................. 17 

TABLE 6–2.—RECOMMENDATIONS BY THE U.S. ARMY CORPS OF ENGINEERS AT LAKE SAKAKAWEA 

Recommendation Number of Sites 

Monitor at Low Water Levels ............................................................................................................................... 2 

Monitor for Erosion and Vandalism ..................................................................................................................... 35 

More Research Required ...................................................................................................................................... 3 

Protect or Mitigate ............................................................................................................................................... 39 

Test for NRHP Eligibility ...................................................................................................................................... 140 

Re-evaluate Site ................................................................................................................................................... 840 

No Further Work Needed—Completely Inundated ............................................................................................... 79 

No Recommendation Available ............................................................................................................................ 64 

Other (Unspecified) .............................................................................................................................................. 14 

A further recommendation would be to prepare a regional research design for the 

study of cultural resources as was done for the Colorado River in Arizona (Fairley 

2003). The purpose of the design would be to guide future research at Indian and 

non-Indian historical and cultural sites affected by the Missouri River in North Dakota. The objective would be to provide a framework for management and treatment 

of cultural resources under the jurisdiction of USACE. 

Table 6–3 contains a summary of impacts, a timeline, and recommendations for 

managing Indian and non-Indian sites along the Missouri River in North Dakota. 

Some of the recommendations can be implemented by various parties of the Task 

Force. For example, the State of North Dakota can conduct public education on the 

importance of preservation of historical and other cultural sites, which can help prevent intentional and unintentional vandalism. Local and private recreational entities can construct and operate facilities with respect for historical and cultural sites 

along the river. The Standing Rock Sioux Tribe and the Three Affiliated Tribes can 

continue to monitor archaeological sites and other sensitive areas that are in danger 

from siltation and erosion. The USACE can limit the range of agricultural and grazing leases to avoid sensitive areas. 

These recommendations can be promoted by all members of the Task Force. Appreciation and understanding of the non-renewable nature of cultural resources is 

the key to managing cultural resources. All parties can be included as stakeholders 

in the development of a research design and plan for the treatment of Indian and 

non-Indian historical and cultural sites. 
240 

TABLE 6–3.—SUMMARY OF IMPACTS AND RECOMMENDATIONS 

Impact Significance Timeline Recommendation 

Inundation (partial, periodic, complete) .......... Substantial ............................................ Long-term—for life of jurisdiction ............................ Monitorat low water levels; data recovery as needed Erosion (cut bank, shoreline, general) ............. Substantial ............................................ Long-term—for life of jurisdiction ............................ Monitor for erosion; stabilize if needed; data recovery as needed General Disturbance ......................................... Moderate ................................................ Long-term—for life of jurisdiction ............................ Monitor; data recovery as needed Agriculture ........................................................ Minor—Moderate ................................... Long-term—for life of lease ...................................... Protect or mitigate with fencing, testing, or data recovery Grazing ............................................................. Minor—Moderate ................................... Long-term—for life of lease ...................................... Protect or mitigate with fencing, testing, or data recovery Construction ..................................................... Substantial ............................................ Short-term—up to 1 year as project progresses ...... Protect or mitigate with fencing, testing, or data recovery Recreation ......................................................... Moderate ................................................ Long-term—for life of jurisdiction ............................ Monitor for activity and vandalism; fence as needed Vandalism ......................................................... Moderate ................................................ Long-term—for life of jurisdiction ............................ Monitor for activity and vandalism; fence as needed All ..................................................................... Minor—Substantial ............................... Short-term (1 to 5 years) ........................................... Prepare research design for cultural resources along the Missouri 

River in North Dakota 
241 

7.0 REFERENCES CITED AND BIBLIOGRAPHY 

Adovasio, J.M., J. Donahue, W.C. Johnson, J.P. Marwitt, R.C. Carlisle, J.D. 

Applegarth, P.T. Fitzgibbons and J.D. Yedlowski. 1980. An inundation study of 

three sites in the Bluestone Reservoir, Summers County, West Virginia. In The final 

report of the national reservoir inundation study volume II, edited by D.J. Lenihan. 

Carrell, T., S. Rayl and D. Lenihan. 1976. The Effects of Freshwater Inundation 

of Archaeological Sites through Reservoir Construction: Literature Search. On file at 

the United States Department of the Interior, National Park Service, Cultural Resources Management Division, Archaeology, Washington. 

Chittenden, Martin Hiram. 1936. The American Fur Trade of the Far West. 2 vols. 

Rufus, Rockwell, Wilson, New York. 

Dahlberg, James C.; Whitehurst, John C. 1990. An overview of Souris River basin 

prehistory in North Dakota. Journal of the North Dakota Archaeological Association 

4:76–110. 

Fairley, Helen. 2003. Changing River: Time, Culture, and the Transformation of 

Landscape in the Grand Canyon. A Regional Research Design for the Study of Cultural Resources along the Colorado River in Lower Glen Canyon and Grand Canyon 

National Park, Arizona. Prepared for the U.S. Geological Survey. Statistical Research, Inc. Technical Series 79. 

Fortier, Andrew C., Thomas E. Emerson, and Fred A. Finney 1984. Early Woodland and Middle Woodland Periods. In American Bottom Archaeology, edited by 

Charles J. Bareis and James W. Porter, pp. 59–103. University of Illinois Press, Urbana. 

Galat, D.L., J.W. Robinson, and L.W. Hesse. 1996. Restoring Aquatic Resources 

to the Lower Missouri River: Issues and Initiatives. In galat, D.L., and Frazier, A.G. 

(eds.), Overview of River-Floodplain Ecology in the Upper Mississippi River Basin, 

v.3 of Kelmelis, J.A., ed., Science for Floodplain Management into the 21st Century: 

Washington, DC, U.S. Government Printing Office, p. 73–92. 

Galat, D.L., C.R. Berry, E.J. Peters, and R.G. White. 2005. Missouri River Basin. 

In A.C. Benke and C.E. Cushing (editors). Rivers of North America. Oxford: 

Elsevier. 

Gilbert, Steve. 2009. Personal communication, Steve Gilbert, USACE Archaeologist, Riverdale office, via telephone with Lucy Bambrey, The Louis Berger Group. 

March 12, 2009. 

Lenihan, D., T.L. Carell, S. Fosberg, L. Murphy, S.L. Rahl and J.A. Ware. 1981a. 

The Final Report of the National Reservoir Inundation Study Volume I. On file at 

the United States Department of the Interior, National Park Service, Southwest 

Cultural Resources Center, Santa Fe. 

Lenihan, D., T.L. Carell, S. Fosberg, L. Murphy, S.L. Rahl and J.A. Ware. 1981b. 

The Final Report of the National Reservoir Inundation Study Volume II. On file at 

the United States Department of the Interior, National Park Service, Southwest 

Cultural Resources Center, Santa Fe. 

Macek-Rowland, K. 2000. Suspended Sediment Loads from Major Tributaries to 

the Missouri River Between Garrison Dam and Lake Oahe, North Dakota, 1954– 

98. U.S. Geological Survey Scientific Investigations Report 00–4072. 

North Dakota State Historic Preservation Office (NDSHPO). 2003. Historic Preservation in North Dakota, II: A Statewide Comprehensive Plan. Historic Preservation Division, State Historical Society of North Dakota. Bismarck, ND. 

Schuler, Harold H. 1990. Fort Pierre Chouteau. University of South Dakota Press. 

Vermillion, South Dakota. 

State Historical Society of North Dakota. 1996. The Centennial Anthology of 

North Dakota History: Journal of the Northern Plains. Edited by Janet Daley 

Lysengen and Ann Rathke. State Historical Society of North Dakota. Bismarck, ND. 

The Louis Berger Group, Inc. (Berger). 2008. Identification of Sources and Deposits and Locations of Erosion and Sedimentation. Prepared for U.S. Army Corps of 

Engineers Omaha District and The Missouri River Joint Water Board. August 2008. 

U.S. Army Corps of Engineers. 2002. Final Lower Snake River Juvenile Salmon 

Migration Feasibility Report/Environmental Impact Statement. Appendix N—Cultural Resources. U.S. Army Corps of Engineers, Walla Walla District. 

U.S. Army Corps of Engineers. 2004a. Jurisdictional Determination for Lake 

Oahe. U.S. Army Corps of Engineers, Omaha District. September 16, 2004. 

U.S. Army Corps of Engineers. 2004b. Final Cultural Resources Management 

Plan Lake Oahe, South Dakota. U.S. Army Corps of Engineers, Omaha District. 

September 2004. 

U.S. Army Corps of Engineers. 2006a. Jurisdictional Determination for Lake 

Sakakawea. U.S. Army Corps of Engineers, Omaha District. April 26, 2006. 
242 

U.S. Army Corps of Engineers. 2006b. Final Cultural Resources Management 

Plan Lake Sakakawea, North Dakota. U.S. Army Corps of Engineers, Omaha District and Three Affiliated Tribes. April 2006. 

U.S. Army Corps of Engineers. 1897. Report of the Chief of Engineers, Appendix 

D. U.S. Army. Capt. H.M. Chittenden, Missouri River Commission. June 30, 1897. 

Wood, Raymond W. and Margot Liberty. 1980 Prehistoric Studies on the Plains. 

Chapter 5 in Anthropology on the Great Plains, edited by Lincoln: University of Nebraska Press, pp. 35–50 (Alfred E. Johnson, senior author). Plains Trade in Prehistoric and Protohistoric Intertribal Relations. Chapter 6, ibid.: 98–109. 

Wood, Raymond W. 1980. The Origins of the Hidatsa Indians: A Review of 

Ethnohistorical and Traditional Data. [Published 1986.] Midwest Archeological Center, Lincoln, Nebraska. 

Zimmerman, Larry J. 1985. Peoples of Prehistoric South Dakota. University of Nebraska Press, Lincoln. 

EXHIBIT 1—LEGAL SECTIONS IN FILES AND LITERATURE SEARCH

The research area search encompasses all or parts of the following sections: 

Township 130N Range 80W Sections 1, 3, 10–15, 22–26 

Township 130N Range 79W Sections 19, 30, 31 

Township 137N Range 80W Sections 16, 17 

Township 137N Range 79W Sections 7, 8, 18 

Township 134N Range 79W Sections 2, 11 

Township 153N Range 102W Sections 9–30, 33–36 

Township 152N Range 102W Sections 5, 6 

Township 153N Range 103W Sections 24 

Township 154N Range 101W Sections 21–24, 28, 29 

Township 153N Range 102W Sections 12, 13, 24, 25, 36 

Township 153N Range 101W Sections 18, 19, 30 

Township 154N Range 100W Sections 19, 29 

Township 154N Range 97W Sections 2, 3, 10, 11, 14, 15 

Township 155N Range 96W Sections 31, 32 

Township 154N Range 96W Sections 2–10, 15–18, 20 

Township 154N Range 97W Sections 1, 2, 11–14 

Township 155N Range 97W Sections 36 

Township 154N Range 96W Sections 1–3, 11–13 

Township 154N Range 95W Sections 18 

Township 154N Range 94W Sections 32–35 

Township 154N Range 94W Sections 36 

Township 144N Range 83W Sections 13, 14, 22–27, 34, 35 

Township 144N Range 82W Sections 8, 9, 18–30, 33–36 

Township 143N Range 82W Sections 1, 2 

Township 144N Range 81W Sections 29–32 

Township 143N Range 81W Sections 6 

Township 134N Range 79W Sections 14, 15, 23, 26, 35, 36 

Township 133N Range 79W Sections 1, 2, 12, 13, 24–26, 34, 35 

Township 132N Range 79W Sections 4, 5, 9, 16 

Township 131N Range 79W Sections 7, 18 

Township 131N Range 80W Sections 12–14, 23–25, 35, 36 

Township 132N Range 79W Sections 15, 16, 28, 32, 33 

Township 131N Range 79W Sections 5, 7, 8, 18 

Township 131N Range 80W Sections 35, 36 

Township 130N Range 80W Sections 1–3, 10–15, 22–26, 36 

Township 130N Range 79W Sections 6, 7, 18, 19, 30, 31 

Township 129N Range 80W Sections 1 

Township 129N Range 79W Sections 4–6, 8–10, 14, 15, 22, 23, 25–27, 35, 36 

Township 152N Range 93W Sections 9, 11, 14–16, 20–23, 27–33 

Township 151N Range 93W Sections 5–8, 16–20, 30, 31 

Township 151N Range 94W Sections 25, 26, 35, 36 

Township 151N Range 93W Sections 30, 31 

Township 150N Range 92W Sections 13, 14, 23–26, 35, 36 

Township 150N Range 91W Sections 18, 19, 30–32 

Township 149N Range 92W Sections 1, 2 

Township 149N Range 91W Sections 6 

Township 148N Range 91W Sections 14–17, 20–23 

Township 148N Range 90W Sections 20–23, 27–29 
243 

EXHIBIT 2—GLOSSARY OF ARCHAEOLOGICAL TERMS

Analysis.—The process of studying and classifying artifacts, usually conducted in 

a laboratory after excavation has been completed. 

Archaeology/archeology.—The scientific study of past human cultures by analyzing the material remains (sites and artifacts) that people left behind. 

Archaeological Site.—A place where human activity occurred and material remains were deposited. 

Artifact.—Any object made, modified, or used by people. 

Assemblage.—Artifacts that are found together and that presumably were used at 

the same time or for similar or related tasks. 

Attribute.—A characteristic or property of an object, such as weight, size, or color. 

B.P.—Years before present; as a convention, 1950 is the year from which B.P. 

dates are calculated. 

Ceramic.—Pottery, fired clay. 

Chronology.—An arrangement of events in the order in which they occurred. 

Classification.—A systematic arrangement in groups or categories according to 

criteria. 

Context.—The relationship of artifacts and other cultural remains to each other 

and the situation in which they are found. 

Culture.—A set of learned beliefs, values and behaviors—the way of life—shared 

by the members of a society. 

Debitage.—The by-products or waste materials left over from the manufacture of 

stone tools. 

Diagnostic Artifact.—An item that is indicative of a particular time period and/ 

or cultural group. 

Excavation.—The systematic digging and recording of an archaeological site. 

Experimental Archaeology.—Scientific studies designed to discover processes that 

produced and/or modified artifacts and sites. 

Feature.—A type of material remain that cannot be removed from a site such as 

roasting pits, fire hearths, house floors or post molds. 

Grid.—A network of uniformly spaced squares that divides a site into units; used 

to measure and record an object’s position in space. 

In Situ.—In the original place. 

Level.—An excavation layer, which may correspond to natural strata. Levels are 

numbered from the top to bottom of the excavation unit, with the uppermost level 

being Level 1. 

Lithic.—Stone, or made of stone. 

Material Remains.—Artifacts, features and other items such as plant and animal 

remains that indicate human activity. 

Midden.—An area used for trash disposal. 

Post Mold/Post Hole.—A type of feature; a circular stain left in the ground after 

a wooden post has decayed; usually indicates the former existence of a house or 

fence. 

Pot Sherd.—A piece of broken pottery. 

Prehistoric.—The period of time before written records; the absolute date for the 

prehistoric period varies from place to place. 

Projectile Point.—A general term for stone points that were hafted to darts, spears 

or arrows; often erroneously called ‘‘arrowheads’’. 

Rock Art.—A general term for pecked, incised, or painted figures on rock. 

Site.—A place where human activity occurred and material remains were deposited. 

Site Steward.—A volunteer who visits a site and helps protect it form vandalism 

and looting. 

Strata.—Many layers of earth or levels in an archaeological site (singular stratum). 

Stratigraphy.—The layering of deposits in archaeological sites. Cultural remains 

and natural sediments become buried over time, forming strata. 

Survey.—The systematic examination of the ground surface in search of archaeological sites. 

Test pit.—A small excavation unit dug to learn what the depth and character of 

the stratum might be, and to determine more precisely which strata contain artifacts and other material remains. 

EXHIBIT 3—ENVIRONMENTAL COMPLIANCE REQUIREMENTS

There are several statutes, regulations, executive orders, and Department of Defense regulations, USACE policies and procedures that require USACE to take into 
244 

account the effects of a proposed action or program on cultural resources. These include, but are not limited to: 

—National Historic Preservation Act (NHPA), 1966 

—Advisory Council on Historic Preservation (ACHP)—Protection of Historic Properties—36 CFR 800 

—Native American Graves Protection and Repatriation Act (NAGPRA), 1990 

—American Indian Religious Freedom Act (AIRFA), 1978 

—Archeological Resources Protection Act (ARPA), 1979 

—Executive Order 11593—Protection and Enhancement of the Cultural Environment, 1971 

—Executive Order 13007—Sacred Sites, 1996 

—Executive Order 13175—Consultation and Coordination with Indian Tribal Governments, 2000 

—National Environmental Policy Act of 1969 (NEPA) 

—Archeological and Historic Preservation Act of 1974 (AHPA), amending Reservoir Salvage Act of 1960 

—Abandoned Shipwreck Act of 1987 

—Army Regulation (AR) 200–4 Cultural Resources Management 

—USACE Rules and Regulations Governing Public Use of Water Resources Development Projects—36 CFR 327 

Compliance with the above listed items ranges from inventory and consideration 

of cultural resources (Indian and non-Indian) by Federal agencies in project planning to monetary fines for destruction, theft, or vandalism of cultural sites. 

Mr. GUNSCH. Just a couple following examples taken from this 

report and tables are attached to my testimony. 

Table 2.13, the Flood Plain Area Comparison, the difference between the 1985 and the 2005 mapping which showed an increase 

in flooding within the Bismarck city limits from 2.7 to 3.6 square 

miles. And within Burleigh County it increased from 28 to 36 

square miles which is an increase of 28.6 percent. That is concerning. 

Appendix F is impacts of siltation on flood control. 

Table 3.1 Flood Elevation Comparison, that goes back to the elevations I discussed earlier on the increases in elevations which in 

the Fox Island area between that 17 year period was about a foot. 

So the base flood elevations have increased significantly. 

The question at this point is what can be done? Interestingly 

enough there’s been a review of the Berger Report. Table 7 includes 

recommendations for addressing sedimentation impacts along the 

Missouri River in North Dakota under flood risks. In the Bismarck/ 

Mandan area there are four key items. 

I have listed them. 

Their tradeoff analysis of the flood control is basically development restrictions or flow restrictions. 

No. 2, study impacts of sedimentations of flood risk when the 

Oahe reservoir is full. 

Three is develop strategies for mitigating ice affected flooding exacerbated by sediment deposition at the headwaters of Lake Oahe. 

Four is conducting debris and snag removal in the Heart River 

confluence area. 

The timeframe to complete these project study items ranges from 

short term to 3 to 5 years with a total cost combined for all of them 

is between $2 and $4.2 million. These are not inclusive of the elements that are currently being reviewed by the Water Resource 

Districts. Therefore additional costs remain to be identified. 

The fourth item on that particular table study list had to do with 

the conducting removal of debris and tree or dead fall trees in the 

Heart River area. The remnants from that 2009 flood will become 
245 

increasingly more difficult to remove once they’re entrapped by additional river sediments. A flood hazard mitigation grant was filed 

or an application was filed with the North Dakota division of Emergency Management in July 2009. And the estimated costs of that 

work was about $430,000. We’ve included a copy of the risk assessment for that particular project as part of our testimony. 

[The information follows:] 

MISSOURI RIVER FLOOD HAZARD MITIGATION—BISMARCK/MANDAN PROJECT

SUMMARY AND RISK ASSESSMENT—DEADFALL TREE REMOVAL GRANT APPLICATION

PROJECT DESCRIPTION

The deposition of fallen trees (deadfall) within the bed and along the banks of the 

Missouri River, during the April 2009 flood event, represents a significant increase 

in the potential flood hazard in this reach. These trees were carried into and deposited within the river channel as a result of significant bank erosion, channel shifts 

and ice flows. They range from 18 inches to 48 inches in diameter and from 20 to 

60 feet in length. The number of deadfall trees varies by location, but they are 

heaviest on the upstream edge of existing or newly formed sandbars, along the eroded river banks lined with native forest, and along the shallower channel areas. 

In addition to the deposition of the deadfall trees the 2009 flood resulted in the 

deposition of a significant amount of sediment generated by the Heart River, bed 

and banks of the Missouri River and other upstream tributaries. Some of these sand 

bars represent new deposition, while existing sandbars were increased in both elevation and width. 

Since the deadfall trees are large and numerous, given projected river flows as 

well as the high Oahe Reservoir elevation, it is unlikely they will be transported 

downstream by normal runoff. As a result they represent a considerable and avoidable risk for the continued accumulation of sediments downstream from the Heart 

River confluence. This is commonly referred to as the Oahe Delta and was the location of the 2009 ice jam that flooded South Bismarck, Fox Island and areas with 

the city of Mandan. The net effect of these trees is much like that of a snow fence 

as waters continue to flow around them and sediment deposition increases. Once 

these trees are submerged by sediment they become entrapped, semi permanent and 

will not move downstream without significant shifts in the river channel. In addition the sediments they collect will also not be flushed downstream into the Oahe 

Reservoir. 

Additional depths from 2 to 3 feet are anticipated to occur within these areas, 

which will result in a measurable reduction in the available floodway conveyance 

within the Missouri River channel. This additional deposition will eventually convert the character of the new sand bars from unvegetated to vegetated, and then 

from vegetated to vegetated, with extended trees and brush. This sandbar growth, 

which again is part of the Oahe Delta formation, will then further restrict open 

channel conveyance thus creating shallower areas. During winter and spring flows 

this significantly increases the risk for ice jams resulting in potential for backwater 

flooding and bank erosion. 

The location of the Oahe Delta within the Missouri River Floodway creates a 

number of primary flood hazards. The first is a continuing increase in the Base 

Flood Elevation (BFE) on the Missouri River and the associated flood risks in South 

Bismarck, Fox Island Area and the city of Mandan. The increase in BFE from 0.8 

to 1.0 foot between the 1985 and 2005 FIRM’s documents this situation and raises 

significant concern. The additional sediment deposited by the 2009 flood has compounded this increase, though an evaluation of the extent of this impact remains 

to be quantified. 

A second significant hazard is the blocking of the Heart River’s confluence into 

the Missouri River and the increased risk for localized ice jams in this area. Such 

ice jams pose a risk not only to create upstream backwater flooding, but also impacts to and the potential failure of the Heart River levee system protecting the city 

of Mandan. While the risk of a given event occurring during the current blockage 

by sediment and trees might be probability based it cannot be taken lightly given 

recent events. Subsequently, proactive action is necessary to alleviate and mitigate 

this known flood hazard. 

A third hazard is the substantial growth of new and existing sandbars within the 

Missouri River channel and floodway that restrict not only the flow of open water, 

but increase the risk for ice jams. The 2009 ice jam occurred within the first 2 miles 

south of the Heart River confluence and was caused by a combination of factors. 
246 

One was the restriction of flows within the Missouri River channel due to existing 

sandbars and new sediment deposited by the event itself. Any additional restriction 

of the channel conveyance by trees and further sediment deposition needs to be addressed in a timely manner. 

After reviewing the extent and nature of the debris deadfall trees and sediment 

deposition within the bed of the Missouri River south of the Heart River Confluence 

consideration was given to the need to remove and dispose of these trees. The future 

removal of the prior and recent sediment deposition within this area is being addressed separately and is not included in nor part of this application. 

When considering the project scope several factors had to be weighed as they relate to direct or indirect impacts and flood hazards. Generally the primary impact 

area for deadfall trees is located within a few miles of the Heart River confluence, 

Missouri River Mile 1311.5 to 1307. The deadfall in this reach has the greatest potential to increase the risk and frequency of ice jams and backwater flooding. Areas 

further south, while having an impact on the overall growth and expansion of the 

Oahe Delta, were not deemed as critical as this southern area is located more in 

the headwaters of the Oahe Reservoir. In addition deadfall trees located along the 

eroded shoreline were excluded from the proposed removal project as they are presently acting as a buffer and natural stabilization measure to limit future bank line 

losses. 

PROJECT PURPOSE

The proposed project is located entirely within the Missouri River floodway. Its 

purpose is to prevent the future deterioration and loss of flow conveyance associated 

with the deadfall trees and future sediment accumulations. The project requires the 

collection, cutting, loading, hauling and disposal of deadfall trees at an offsite location. The removal process requires the contractor to use several barges and a tug 

boat to haul equipment along the river channel and onto the sandbars to collect, 

cut, load and haul deadfall trees to an area where they would be transported to a 

disposal site. The deadfall trees within the river would be loaded by crane onto the 

barge or towed upstream using the tugboat to an off load point along the river bank. 

The larger deadfall on the sandbars would be cut into sections suitable for collection 

then loaded onto the barge for transport and disposal. 

Both aerial and ground photos were taken to document the approximate location 

and extend of deadfall trees within and along the river. A ground survey was then 

completed to document the location and general size distribution of the deadfall 

trees and provide an indication as to the approximate number that need to be removed, which is necessary to determine the opinion of probable cost. A photo record 

of the areas of concern and typical situations is included in this project summary. 

OPINION OF PROBABLE COST

The Opinion of Probable Cost (OPC) to remove the deadfall trees was determined 

based on the number of trees to be removed, their location and the equipment and 

time required. Based line cost data was gathered from various contractors who have 

completed similar work. This cost opinion was then completed using the best available data at the time this application was prepared. Bidding and contracting for this 

work has the probability of resulting in either higher or lower costs depending upon 

a number of factors including, but not limited to, economic conditions, time of work, 

and contractor availability. The OPC for this project is approximately $430,100 or 

roughly an average of $3,162 per deadfall tree. 

BENEFIT—COST RATIO DETERMINATION

The development of a benefit to cost ratio to justify the mitigation funds required 

a certain amount of generalization and estimation of present values. First, the risk 

for ice jams varies from year to year and is based on a number of climatic factors 

and the probability for various stream flows. Since the probability for such an event 

exists in any given year it is assumed that flood flows can and will occur, therefore 

waiting to mitigate avoidable damages is not an acceptable option. 

The basis for benefits provided by the deadfall tree removal is measured in two 

separate ways, which are cumulative. First, is to avoid further losses in channel 

conveyance associated with the accumulation of sediments over, around and downstream from the deadfall trees. Second, is to avoid the expenditure of public and 

private resources to fight an ice jam flood event resulting from this additional sediment accumulation. 

The continued sediment accumulation increases the potential frequency for ice 

jam and higher flood events. The cost to remove these deadfall trees also increases 

dramatically if they are covered or entrapped in future sediment deposition. These 
247 

additional sediments would have to be removed to access these trees; therefore removal of these materials is necessary not only to access the trees to prevent future 

deposition but to restore the lost channel conveyance. The value of not having to 

remove these sediments in the future is deemed a present value benefit of the removal project. The removal costs are based on the use of a hydraulic dredge to avoid 

the placement or relocation of fill materials within the Missouri River Floodway. 

Discharge, disposal and storage of these materials most likely would occur on the 

left bank on properties owned by the State of North Dakota. 

The present value benefit associated with the deadfall tree removal was determined based on the projected cost to hydraulically dredge the projected accumulated 

sediments associated with the tree’s location within the river. Utilizing an approximation of the aerial extent and depth of sediment deposition over, around and 

downstream from an average size tree it was determined that from 300 to 400 Cubic 

Yards of material would be captured by each. While this could occur in 1 year or 

over a period of years the net accumulation was totaled for removal based on a 

present day cost per cubic yard. The benefit is provided by the removal of the 

deadfall trees before these sediments accumulate. The present value cost is based 

on a projection of approximately 125 sites, 350 CY per site, and $17 per cubic yard 

for sediment removal. 

Sediment Removal Benefit—$743,750 

A 10-year event is used to define the present value cost to defend the communities 

against an ice jam flood, which is a flow rate of 68,500 cfs on the Missouri River 

below the Heart River confluence. Estimates of the actual 2009 flood flow vary, but 

likely ranged from 80,000 cfs to 90,000 cfs. It is projected that currently a major 

ice jam during the 10 year flood event could result in similar impacts, or the expenditure of resources as the 2009 flood. The cost to defend against an ice jam event 

flood varies dependent upon its location, nature, extent and duration. For the purposes of this assessment it is deemed that the general preparedness and resources 

necessary to battle a similar event are a reasonable basis for projecting the present 

value cost for the flood hazard. It is not specifically known if the ice jamb event 

could result from existing sediment deposition without the removal project; however, 

the additional accumulation will measurably increase the current flood hazard. A 

current conditions analysis is unavailable. 

Based on contacts with the city of Bismarck, city of Mandan, the Burleigh and 

Morton County Emergency Managers, and the North Dakota National Guard we 

were able to obtain the following estimated public costs associated with the 2009 

flood event. The figures provided are for reimbursable expenses only and do not include employee or staff time, or private property financial impacts. 

PUBLIC RESOURCE COST—2009 FLOOD EVENT 

Amount 

City of Bismarck—Tabulation of FEMA Reimbursable Expenses ........................................................................... $464,000 

City of Mandan (estimated) ..................................................................................................................................... 200,000 

North Dakota National Guard—Ice Jam Demolition ............................................................................................... 80,000 

Total ............................................................................................................................................................ 744,000 

The private cost to defend against the 2009 event or damages incurred were not 

readily available, from the sources contacted, at the time this application was completed. 

Private Costs (Undetermined)—$ Unknown 

Both the Public and Private costs are additive utilizing a 10-year timeframe the 

probability of a 10 year event occurring within the next 10 years is approximately 

39 percent. Therefore, the following is the projected present value benefit of the 

project: 

Public resource Benefit—$744,000 × 0.39 = $290,160 

BENEFIT—COST SUMMARY 

Amount 

Total Present Value Benefit: 

Public Resources Benefit ............................................................................................................................ $290,160 

Private Resources Benefit ........................................................................................................................... ( 1 ) 
248 

BENEFIT—COST SUMMARY—Continued 

Amount 

Sediment Removal Benefit .......................................................................................................................... 743,750 

Total ........................................................................................................................................................ 1,033,910 

Total Present Value Costs: 

Projected Deadfall Tree Removal and Disposal ......................................................................................... 430,100 

1 Undetermined. 

Combined B/C Ratio $1,033,910/$430,100 = 2.40:1 

SUMMARY NOTES

The B/C ratio does not include the private benefits associated with avoidance of 

damages associated with an ice jam flood event. Inclusion of this figure would further increase the B/C ratio. 

The B/C ratio does not include the lost Federal hydropower revenues associated 

with the need to cut releases during an ice jam event or the restricted flows under 

the ice due to the existing and future sediments. These costs were not quantified 

as part of this evaluation. 

The projected costs are based on early projections of time and materials required 

to complete the project. Additional evaluation and design may result in savings once 

the plans and specifications have been completed. 

ACKNOWLEDGMENTS OF DATA SOURCES

Dale Frink, PE, North Dakota State Engineer 

North Dakota State Water Commission 

Burleigh County WRD 

Morton County WRD 

Lower Heart WRD 

City of Bismarck 

City of Mandan 

Burleigh County Emergency Management 

Morton County Emergency Management 

Square Butte Dredging, Morton County—Hydraulic Dredging Cost Data 

Ron Sando, PE, Engineering Consultant 

Adventure Divers, Inc, Minot North Dakota—Construction Cost Data 

Corps of Engineers—Bismarck Regulatory Office 

USFWS—Threatened and Endangered Species Data 

NDGF—Enforcement Division 
249 

APPENDIX A—AERIAL AND FIELD RECONNAISSANCE PHOTO RECORD
250 
251 
252 
253 
254 
255 
256 
257 
258 
259 
260 
261 
262 

Mr. GUNSCH. This grant application was declined. And the 

project was deemed to be snagging and clearing which is interpreted by maintenance under FEMA’s guidelines. That decision has 

been appealed and is still under review at this point in time. 

I’ll paraphrase a couple other issues. 

Restoring and maintaining flood water conveyance in the Missouri River system through the Bismarck/Mandan area is of critical 

importance, as is pointed out by all of us being here this evening. 

Since flood protection is the No. 1 priority for the management of 

the Missouri River system and the issue of flood protection for Bismarck/Mandan should be a high priority as well. The development 

of mitigation measures whether they include development controls, 

dredging, channel modifications, levees or other measures or combinations thereof, need to have attention now to reduce and manage the risk for future flood events. 

Another critical issue in the discussion for any flood control or 

flood hazard mitigation project is the operation and maintenance. 

And the question has to be asked who maintains the river? While 

the riverbed is sovereign land owned by the State of North Dakota, 

the Federal Government has taken and accepted control and management of the river system. 

As flood protection and sedimentation issues are a function of 

that management and maintaining flood conveyance should be a 

Federal responsibility. We understand this requires the Federal 

Government to establish the necessary authorities to allow the 

Corps to participate in that effort. We’re also aware of the many 

ongoing reviews and studies regarding the Missouri River including 

MRRIC, MRERP, MRAPS and others. And while each has its own 

commendable effort in their own right, none should preclude the 

advancement and development of what hazard mitigation efforts to 
263 

protect Burleigh and Morton County and the communities of Bismarck and Mandan. 

A final concern is the completion of the Missouri River cumulative environmental impact statement as there are those who are 

holding up that particular study on the river at this time. 

And if you’d indulge me just a moment, I’d read a statement 

from the Water Resource District relative to the Fox Island area. 

‘‘The March 2009 Missouri River ice jam flood event had significant impact on 

residents in the Fox Island area located in South Bismarck. This flood happened 

very quickly and with such little notice to the residents who subsequently had very 

limited ability and time to prepare or even respond to protect their properties. During a recent public informational meeting Fox Island residents were able to provide 

comments and concerns to the Burleigh County Water Resource District regarding 

these events and we summarized these in four major points. 

‘‘Having lived on the river for many years some residents noted that the Corps 

did not raise the river level this winter and again this spring to break up the ice 

flows as they’ve seen in the past. And they question why? Others question why the 

Corps is relying on a gauge that is several miles upstream from Fox Island on which 

to base the response for ice jam flooding. Thus, in their opinion the Corps’ reaction 

was delayed. And the State of North Dakota had to request action to reduce releases 

from Garrison Dam. 

‘‘There needs to be more attention paid to the sedimentation issue and ice jam 

risks as the delta formation is growing and needs to be addressed. And what impacts are the proposed developments having on Missouri River flood plain elevations? And we provided a copy of the power point presentation that was made by 

the Water Resource District to those residents to give you some background as well. 

‘‘The Burleigh County Commission, the Burleigh County Highway Department 

and the Water Resource District have taken a proactive approach to the issues that 

happened. They’re looking at mitigating to the extent possible within reasonable 

economic means those issues that happened after the 2009 flood. One critical problem encountered during the flood was the inability to access these residential areas 

because the primary access roadways were inundated. The county and township are 

in the process of implementing several road grade raises to improve emergency access for such events. And while not providing 100 year access it is a measured, economical approach to the access issue. 

‘‘The Burleigh County Water Resource District has also formally requested that 

the city of Bismarck and Burleigh County revise their current flood plain management ordinance to require the first floor flood elevations and crawl spaces for new 

construction to be placed a minimum of 2 feet above the base flood elevation which 

is currently higher than the one foot requirement. 

‘‘In addition a number of local residents have signed a petition to the Water Resource District to implement flood control measures to protect them as reasonably 

practical from limited ice jam flood events. Again, while this will not provide 100 

year flood protection, there is some ability to provide additional protection under existing conditions. Even so residents remain at significant risk for flooding in adverse 

impacts from ice jams and high water events still exist. 

‘‘Another mitigation measure under consideration is the development of emergency action and response plan to govern the actions during the next such event. 

We understand to some extent this may require the update of the Burleigh County 

Multi-hazard Mitigation Plan to incorporate those future flood scenarios. While 

these measures are being implemented it is requested that the Corps conduct a post 

flood elevation. This should include a written report to the Burleigh County, Morton 

County and the State of North Dakota on how the flood event occurred from a river 

management perspective and what if any, reservoir control and operation measures 

might be implemented to mitigate future risks.’’ 

PREPARED STATEMENT

And that particular statement was submitted and read by myself 

for Gailen Narum, the Chairman of the Water Resource District. 

Thank you. 

[The statement follows:] 
264 

PREPARED STATEMENT OF MICHAEL GUNSCH

Senator Dorgan and subcommittee, thank you for the opportunity to provide testimony regarding the flooding concerns in the Bismarck-Mandan area. 

My name is Michael Gunsch. I am a resident of Bismarck, and a registered professional engineer in the State of North Dakota and principal in the firm of Houston 

Engineering. Houston Engineering is currently the district engineer for the Burleigh 

County Water Resource District and is an engineering consultant to the Morton 

County Water Resource District. My remarks today are presented on behalf of the 

BCWRD, MCWRD and the Lower Heart Water Resource District (LHWRD) and relate primarily to the technical nature of the flooding issues. 

In July 2009 Houston Engineering was retained by the BCWRD in cooperation 

with the MCWRD and LHWRD to identify alternatives to mitigate flood hazards associated with the Missouri River. The costs for this effort are underwritten in part 

through a cost share grant from the North Dakota State Engineer. The primary 

focus is to define pre-disaster mitigation alternatives that can be implemented to 

reduce the existing and projected flood risks for Burleigh and Morton County. After 

evaluating the March 2009 ice jam flood event and reviewing prior studies, the following objectives were developed for further consideration: 

—Sediment and debris removal from within the upper reaches of the Oahe Delta 

formation below the Heart River Confluence to mitigate the impacts and risks 

associated with ice jam flood events and future sediment deposition; 

—Evaluate the status of potential aggradation and on-going changes in stream 

channel conveyance downstream from Bismarck-Mandan and its impact on the 

risks associated with ice jam and open water flood elevations; 

—Evaluate the feasibility of alternatives to lower the current Base Flood Elevation (BFE) to those levels documented in the 1985 Flood Insurance Study 

(FIS). The focus to be on the reach between the USGS Bismarck Gage at Missouri River Mile 1314.5 south to approximately Missouri River Mile 1302 

(approx. Oahe Project Boundary). Alternatives shall include, but not be limited 

to, dredging, channel improvements, reservoir operations, and structural measures or a combination thereof; 

—Define existing and future land uses within and proposed bank stabilization 

measures along the Missouri River Correctional Facilities property, as necessary, to achieve the objectives outlined in Item No. 1, Item No. 2 and Item 

No. 3. There is nexus between project construction or dredging within and along 

the river and the need for access and potential use of adjacent properties for 

the placement of dredge materials; and 

—Complete an assessment to determine the potential (economic) flood damages or 

impacts associated with future increases in the Missouri River BFE and flood 

risks in Burleigh and Morton Counties. This effort includes a GIS based analysis of the existing and potential flood impact areas. 

The tasks and potential costs associated with accomplishing these objectives, 

which include local, State and Federal issues, are still under development. 

Concerns regarding the Oahe Delta have been around for many years with no action taken since 1985 to address the eventuality of what might occur. The March 

2009 ice jam flood event significantly increased everyone’s awareness of the issue 

and subsequently has raised the level of concern. The Corps of Engineers (COE) August 1985 study entitled Oahe-Bismarck Area Studies, Analysis of Missouri River 

Flood Potential in the Bismarck, North Dakota Area evaluated various alternatives 

to mitigate flood impacts associated with the continuing delta formation. A copy of 

this report is provided for reference. These included options such as dredging, channel cutoffs, bank stabilization, levees, Garrison operational changes, Oahe operational changes, land acquisition and floodplain management. The study’s conclusion was to change reservoir operations to minimize releases during critical high 

discharge periods, and to recommend communities consider implementing additional 

criteria for floodplain development, raise access roadways, and encourage participation in the National Flood Insurance Program. Given the March 2009 event we have 

to question if operational changes alone are adequate to address the ice jam risks. 

The 1985 study predicted that the base flood elevations (BFE’s) in the Burleigh 

and Morton County areas would increase and over time eventually reaching a projected equilibrium. Unfortunately these increases and the equilibrium elevations occurred in a 17 year period between the 1981 and 1998 data sets. These increased 

BFE’s are reflected in the 1985 and 2005 Flood Insurance Study (FIS) respectively. 

There are a number of professionals who agree this is not the end of the increases 

that will be experienced, therefore more needs to be done before the situation deteriorates further, and we are already 10 years past the last data set. 
265 

More recently the COE under section 108—Missouri River Protection and Improvement Act 2000—title VII enlisted the professional engineering services of The 

Louis Berger Group, Inc. to complete a report entitled Impacts of Siltation of the 

Missouri River in the State of North Dakota Summary Report 29, June 2009, 

[Berger Report]. A copy of the Berger Report is provided for the record for reference 

as it contains significant information and data that documents and justifies our concerns. The following examples are taken from this report and copies of these tables 

are attached to my testimony for direct reference: 

TABLE 2.13—FLOODPLAIN AREA COMPARISON

Table 2.13 provides a tabular summary of the expansion of the special flood hazard areas or floodplain between 1985 and 2005. Based on this table flooding on the 

100-year event during this period within the Bismarck City limits has increased 

from 2.7 to 3.6 square miles, while in Burleigh County it has increased from 28 to 

36 square miles. This represents a 28.6 percent increase or expansion of the floodplain between the two studies. No data was provided for Morton County. 

APPENDIX F—IMPACT OF SILTATION ON FLOOD CONTROL, TABLE 3.1—FLOOD ELEVATION

COMPARISON

Table 3.1 illustrates the documented increases in the base flood elevations along 

the Missouri River system from 1985 to 2005. The average increase being around 

1 foot on the 100 year event in the Fox Island area south of Bismarck. While development standards within this special flood hazard area have changed, continuing 

increases in the flood elevations presents a significant challenge and unknowns, 

which have diminished the value of those efforts. Therefore, more information is 

necessary to protect those located within the floodplain and to adequately protect 

potential future development. 

So the question is this—What can be done? 

The response to this is fairly direct and documented in the Berger Report in the 

following: 

TABLE 7: RECOMMENDATIONS FOR ADDRESSING SEDIMENTATION IMPACTS ALONG THE

MISSOURI RIVER IN NORTH DAKOTA, UNDER FLOODING RISKS IN THE BISMARCK/ 

MANDAN AREA

This table lists the following four Study/Product Items: 

—Tradeoff Analysis of Flood Controls (e.g., development restrictions vs. flow restriction). 

—Study impacts of sedimentation of flood risks when Lake Oahe pool is full. 

—Develop strategies for mitigating ice-affected flooding exacerbated by sediment 

deposition at the headwaters of Lake Oahe. 

—Conduct debris/snag removal in the Heart River confluence area. This will minimize sediment accumulation in the area and decrease the likelihood of ice-affected flooding. 

The timeframe to complete each of these Project/Study items ranges from short 

term, to 3 to 5 years. The total combined costs range from $2 million to $4.2 million. 

These Project/Study costs are not inclusive of all the elements under consideration 

by the BCWRD, MCWRD and LHWRD. Therefore, there are additional costs that 

remain to be identified. 

The fourth item on the Project/Study list, to conduct debris/snag removal (e.g., 

deadfall trees), is one of immediate concern to reduce the risk for the recurrence 

of ice jams south of the Heart River. The debris remnants from the 2009 flood will 

become increasingly more difficult to remove once they are covered by additional 

river sediments. A Flood Hazard Mitigation Grant was submitted to the North Dakota Division of Emergency Management in July 2009 to complete this mitigation 

work and had a projected cost of around $430,100. A copy of the Project Summary 

and Risk Assessment included in this application is provided as a reference with 

this statement. This grant application was declined the project was deemed to be 

snagging and clearing which is interpreted to be maintenance under FEMA’s guidelines. This decision has been appealed and will undergo further consideration. 

It should be noted that there are more benefits provided than were specifically 

presented in the Project Summary and Risk Assessment as not all costs were readily available at the time of application. We now understand the cost to the rural 

electric power cooperatives alone, due to the need to purchase replacement power 

during reduced releases from Garrison Dam during the ice jam event, was in excess 

of $2 million. As additional background the 1985 study noted the loss in ability to 

generate hydropower due to sedimentation had an economic loss ranging from near 
266 

1 Remus, John, Personal Communication, November 2008. 

2FEMA. Flood Insurance Study—Burleigh County, North Dakota and Incorporated Areas. FIS 

Number 38015CV000A. Federal Emergency Management Agency, July 2005. 

zero in 1985 to a full annualized loss amount of $500,000, in 1985 dollars, occurring 

around 2005. This economic loss is directly related to operational changes caused 

by a reduction in flow capacity during the winter associated with sedimentation and 

ice conditions. 

Restoring and maintaining floodwater conveyance in the Missouri River system 

through the Bismarck-Mandan area is of critical importance. Since flood protection 

is the number one priority for management of the Missouri River system the issue 

of flood protection for Bismarck-Mandan should be a high priority as well. The development of mitigation measures whether they include development controls, 

dredging, channel modifications, levees, other measures, or a combination thereof 

need to have attention now to reduce and manage the risks for future flood events. 

Another critical issue for any flood control or flood hazard mitigation project is 

operation and maintenance. The question has to be asked—who maintains the Missouri River? While the riverbed is sovereign land owned by the State of North Dakota the Federal Government has taken and accepted control and management of 

the river system. As flood protection and sedimentation issues are a function of that 

management, maintaining flood conveyance should be a Federal responsibility. We 

understand this will require the Federal Government to establish the necessary authorities to allow the COE to participate in this effort. 

We are aware of the many ongoing reviews and studies regarding the Missouri 

River including MRRIC, MRERP, MRAPS and others. While each of these is a commendable effort in their own right none should preclude the advancement and development of flood hazard mitigation efforts to protect Burleigh and Morton County 

and the communities of Bismarck and Mandan. A final concern is the completion 

of the Missouri River Cumulative Environmental Impact Statement as there are 

those who are holding up any project on the river until this is completed. 

Thank you for the opportunity to present this information. 

TABLE 2.13.—FLOODPLAIN AREA COMPARISON 

Burleigh County Bismarck City Limits 

1985 100-year Floodplain—28 mi2 ......................................... 1985 100-year Floodplain—2.7 mi2

2005 100-year Floodplain—36 mi2 ......................................... 2005 100-year Floodplain—3.6 mi2

mi2= square miles. 

In urban areas such as Bismarck and Mandan, flood plain development restricts 

the Missouri River’s ability to accommodate increases flows during certain storm 

events (e.g. river channel has no room to widen without affecting properties). 

Aggradation in this area of the river compounds the problem resulting in an increase risk of flooding and the loss of property. Potential buyouts due to flooding 

concerns in the Bismarck-Mandan area are estimated at over $100 million.1 The impact of flooding is estimated to be greatest between RM 1300 and 1316, i.e., in 

downtown Bismarck and Mandan.2 Flooding also occurs outside of urbanized areas, 

affecting cropland and causing soil erosion. 

Property owners whose property now lies within the expanded flood plain may 

also be impacted by a decline property values and increased insurance cost. Homes, 

businesses, and agricultural land are among the types of properties most heavily affected by an increase in the 100-year flood plain. 

FEMA manages the National Flood Insurance Program (NFIP) which insures 

buildings and structures against flood damage. As a result of changes in the Flood 

Insurance Rate Map, all entities requiring a mortgage for structures on property 

within the 100-year floodplain will be required to purchase insurance under the 

NFIP. Owners of buildings must purchase insurance against damages to the structure of the building itself and also against damages to the contents of any floors 

below flood level that would be inundated in the event of a 100-year flood. Owners 

may purchase a basic level of coverage or increase coverage for an additional cost. 

The cost of the insurance is based on the area of the building (square feet). The insurance rate per square foot is dependent on the building’s characteristics, on the 

date of construction of the building, and on the ‘‘flood zone’’ that the building is located in. 

There are four different types of buildings covered under NFIP: Non-residential; 

Single-family dwellings; Condominiums; and 2–4 family dwellings. 
267 

TABLE 3.1—FLOOD ELEVATION COMPARISON 

Key Milestone River Station 

Flood Elevations, (feet) NAVD Changes in Flood Elevations 

from 1988 to 2005 (feet) 

1988 Flood Data 2005 Flood Data 

50 yr 100 yr 500 yr 50 yr 100 yr 500 yr 50 yr 100 yr 500 yr 

Confluence Apple Creek .................................................................................................................................... 1,300.21 1,626.7 1,627.7 1,631.0 1,627.9 1,629.0 1,632.1 1.2 1.3 1.1 Confluence Little Heart River ........................................................................................................................... 1,302.22 1,628.3 1,629.3 1,632.8 1,629.6 1,630.7 1,633.8 1.3 1.4 1.0 Confluence Heart River ..................................................................................................................................... 1,310.72 1,633.7 1,634.9 1,638.3 1,634.5 1,635.7 1,638.8 0.8 0.9 0.5 Bismarck Expressway ....................................................................................................................................... 1,313.41 1,635.1 1,636.3 1,639.8 1,636.0 1,637.3 1,640.4 0.9 1.0 0.6 Memorial Bridge ............................................................................................................................................... 1,314.21 1,635.4 1,636.5 1,640.0 1,636.3 1,637.5 1,640.8 0.9 1.0 0.7 Railroad ............................................................................................................................................................ 1,314.99 1,635.9 1,637.0 1,640.5 1,637.7 1,637.9 1,641.2 1.8 0.9 0.7 Interstate 94 ..................................................................................................................................................... 1,315.49 1,636.1 1,637.3 1,640.7 1,636.9 1,638.1 1,641.5 0.8 0.9 0.8 City of Bismarck Limits .................................................................................................................................... 1,317.42 1,637.7 1,638.9 1,642.9 1,638.2 1,639.6 1,643.6 0.5 0.7 0.6 Confluence Burnt Creek .................................................................................................................................... 1,319.88 1,638.9 1,640.0 1,643.9 1,639.5 1,640.8 1,644.6 0.6 0.8 0.8 Burleigh County Limits ..................................................................................................................................... 1,328.64 1,644.0 1,645.0 1,648.5 1,643.7 1,644.8 1,648.4 ¥0.3 ¥0.2 ¥0.1 

Source: Elevations are from HEC–2 data and HEC–RAS data from the 1988 and 2005 Flood Insurance Studies, respectively. 

TABLE 7.—RECOMMENDATIONS FOR ADDRESSING SEDIMENTATION IMPACTS ALONG THE MISSOURI RIVER IN NORTH DAKOTA 

Input/Resource/Study/Product Timeline Cost Remarks 

Flooding Risks in Bismarck/Mandan Area: 

Tradeoff Analysis of Flood Controls (e.g. development restrictions vs. flow restrictions) ........................................ Short term ............................ $500,000–$1,000,000 .......... Would require local partner Study impacts of sedimentation on flood risks when Lake Oahe pool is full .......................................................... Two to three years to complete. $500,000–$ 1,000,000 ......... Would require a cost-share sponsor Develop strategies for mitigating ice-affected flooding exacerbated by sediment deposition at the headwaters 

of Lake Oahe.

Three to five years to complete. $500,000–$1,000,000 .......... Would require a cost-share sponsor. 

Detailed Environmental Assessment (EA), may be an 

EIS 

Conduct debris/snag removal in the Heart River confluence area. This will minimize sediment accumulation in 

the area and decrease the likelihood of ice-affected flooding.

Short term; Less than two 

years to complete.

$100,000–$150,000 for design.$400,000 to $1,000,000 for 

construction.

Would require a cost-share 

sponsor 

Garrison Reach: 

Complete cumulative Environmental Impacts Statement (EIS) for Garrison Reach ................................................. Two to three years to complete. $1,000,000–$2,000,000 ....... Would require a cost-share sponsor 
268 

TABLE 7.—RECOMMENDATIONS FOR ADDRESSING SEDIMENTATION IMPACTS ALONG THE MISSOURI RIVER IN NORTH DAKOTA—Continued 

Input/Resource/Study/Product Timeline Cost Remarks 

Conduct bank stabilization projects .......................................................................................................................... Short term; Less than one 

year to complete.

$300,000–$500,000 per 

site.

Very difficult without EIS 

Evaluate potential operational changes of the Garrison Dam and/or flow modifications ....................................... Three to five years to complete. $1,000,000–$5,000,000 ....... Controversial; Re-opens master manual issues; 

Possibly outside the scope of title VII 

Fish and Wildlife: 

Study to evaluate the needs of multiple species along the Missouri River ............................................................. ............................................... $250,000–$300,000 (Twoyear study). Would require a cost-share sponsor. Overlap with the 

BiOp could be complicated 

Study the life-cycle of the pallid sturgeon on the Yellowstone River ....................................................................... ............................................... $200,000–$250,000 (Twoyear study). This is part of the Missouri River Recovery Program 

Cultural Resources: 

Prepare a research design for cultural resources along the Missouri River. Provide a framework for management and treatment of cultural resources across jurisdictions. Short term; less than two years. $200,000–$250,000 ............. Would require a cost-share sponsor Study to access cultural and historical resource sites to determine if impacts are occurring .............................. Short term; less than two 

years.

$250,000–$500,000 ............. Would require a cost-share 

sponsor 
269 

Senator DORGAN. Mr. Gunsch, thank you very much. We appreciate your testimony. By the way, you cited the Missouri River cumulative environmental impact statement. I’m not familiar with 

that. 

What are you referring to? 

Mr. GUNSCH. The cumulative environmental impact statement 

was being written and evaluated for bank stabilization facilities. In 

other words there was an issue where people want to stabilize their 

banks along the Missouri River and issued permits because the environmental groups are saying the cumulative impact of all those 

facilities is having an adverse effect on the river. 

Senator DORGAN. Who’s conducting that? 

Mr. GUNSCH. I believe the Corps was doing the original study. 

Senator DORGAN. Colonel Ruch, are you familiar with that? 

Colonel RUCH. My familiarity is with the length of bank. Right 

now I think they’re down to where they can only do a 200 foot section at this time. And I know there is some ongoing work. But I’ll 

have to give you an update on that. 

Senator DORGAN. Alright. Roger indicates it may be a regulatory 

function. But we’ll check back on that. 

Let me try to understand, Mayor Warford, you talked about 

heavy spring runoff. Do we know how heavy the spring runoff was? 

Is this like once in 50 years? Once in 100 years? 

Does anybody know? 

Mr. WARFORD. I certainly don’t know. I do know that, you know, 

we had 100 inches, within an inch of an all time record snow last 

year in the city of Bismarck. So that would lead me to the conclusion that we had significantly more runoff last year than we’ve had 

in most years. 

Senator DORGAN. Colonel, have you studied this? 

Colonel RUCH. All it takes on top of the 100 inches we had is a 

very rapid meltoff and rainfall on top of that. And that kind of 

gives a worse case situation where you get all that released at one 

time. 

Senator DORGAN. Alright, and that was in addition the ice jams? 

Colonel RUCH. Yes. 

Senator DORGAN. Ok. 

Mr. Royse, you talked about the title VII program. I want to ask 

you and the Colonel where we are on that. Is my understanding 

correct that there’s been a reconnaissance study on that and to 

move to the next stage would require a local sponsor? 

Colonel, is that correct? 

Colonel RUCH. It is correct. And Mr. Gunsch did a good job of recapping his table 7 that he submitted. Basically the legislation outlined three phases. 

The first phase was an assessment which has just been completed. 

The second phase of the plan would identify selection criteria for 

the project’s implementation process of those projects he actually 

discussed. 

The third phase would go to construction. 

The assessment was a cost-shared study with the Missouri River 

Joint Water Board. And it identified these projects that he listed 

for task force consideration in the plan and project phases. The as-
270 

sessment was completed in 2009, but no sponsors have stepped forward to cost share. 

Senator DORGAN. Now you would not move forward unless 

there’s a local sponsor. And the local sponsor at that next stage, 

that’s a 50/50 cost-share, is it? 

Do you know? 

Colonel RUCH. I believe it’s a 75/25 cost-share on that. 

Senator DORGAN. Is it? Ok. 

Colonel RUCH. It’s a little different than most. 

Senator DORGAN. But in order for you to move to the next phase 

you need a local sponsor? Is that your understanding, Mr. Royse? 

Mr. ROYSE. Senator, that is correct. And the Missouri River Joint 

Board was a local sponsor on the study. This is the study. It is 

complete. 

Senator DORGAN. Is it likely that there will be a local sponsor for 

the following step? 

Mr. ROYSE. Well, Senator, I will tell you this. That of the projects 

they identified most of the projects appear to be further studies. 

And we have a concern about that. 

Senator DORGAN. Ok. 

Mr. ROYSE. And so if there are further studies I’m not sure the 

Missouri River Joint Board would be a sponsor on that. 

Senator DORGAN. Alright. Colonel, if a local sponsor is required 

to come up with local money for additional studies, I assume what 

Mr. Royse is referring to is that they would like to see something 

other than a study. So how do they get to that point? 

Colonel RUCH. We have to go through that next phase and do 

this study. Even on the number four that he discussed which was 

debris and sag removal from the Heart River, we still have to do 

the environmental documentation that you discussed at the beginning of the testimony to be able to go to construction. So it’s not 

as simple as going out there and getting the work. 

Senator DORGAN. Let me have you describe for us, Colonel, if you 

would, what are the authorities that the Corps of Engineers has 

available to relate the flooding problems in this area? 

Colonel RUCH. I think we’ve discussed several, especially title VII 

of WRDA 2000. But some of the others that you may be referring 

to would be section 205 or section 208. I could give you a little bit 

of a detail on them. 

Senator DORGAN. Just give us a thumbnail of those two. I’m generally familiar with them. 

Colonel RUCH. Section 205 provides standing authority for the 

Corps to study and implement flood damage reduction projects 

without specific authorizations for those projects. 

Section 205 projects can consist of structural or non-structural 

flood risk reduction measures to protect urban areas including 

towns and villages. 

Feasibility studies investigate. It is cost-shared 50/50 for Federal, 

non-Federal. And for any cost above the initial $100,000 in unmatched Federal money, construction is shared at 65/35 as you 

stated earlier. 

This program generally looks at small to moderate sized projects 

with construction costs capped at about $7 million. 
271 

Senator DORGAN. I would like to ask about the issue of debris removal, and several have mentioned that tonight. Is debris removal 

something that generally would require less environmental analysis than dredging, for example or larger flood control projects? 

Colonel RUCH. You have to go through the basic steps of an environmental assessment. So until you actually study and see what 

the environmental conflicts would be, I can’t really say that it’s 

simpler. It has to do with the ecosystem you’re involved in. 

As you know we’re involved in an area that is under the BiOp. 

So there are many organizations that we have to satisfy. 

Senator DORGAN. I’ve got a number of questions for other witnesses as well, but I want to try to understand a bit, if I can, the 

discussion about debris. The discussion about silting. A series of 

things have been discussed here about what I think is probably incontrovertible with respect to the condition of the river that exacerbates flooding. 

The question is who’s responsible for trying to do something 

about that, debris removal or dredging? Is the Corps responsible? 

Colonel RUCH. This area is not within the limits of our project. 

So we do not have the ability to go out there without an additional 

study. We cannot do it within the operations of our reservoir because it’s not within our reservoir boundaries. 

Senator DORGAN. Are there additional necessary authorities that 

you need? 

Colonel RUCH. No. I believe within title VII of WRDA 2000 and 

the other authorities we have discussed we could move forward if 

we identified a cost share partner. 

Senator DORGAN. Ok. What would be the length of the studies, 

for example under title VII that you’re describing? 

Colonel RUCH. A year to 18 months. We believe that it would be 

less than 2 years to complete. And that’s on table 7 that was referenced. 

Senator DORGAN. Mr. Royse, Mr. Gunsch, you both spoke of this, 

I’m trying to understand if there are things that can be done and 

the Corps has existing authority, provided it goes through the 

steps. How long does it take to get through the steps to actually 

do the things that we believe will mitigate the potential for future 

flooding? 

Colonel RUCH. It was referred to in the 1980s. There was a study 

done like this. And granted we are many years later, but many of 

these things were discussed back then. And we did not get a cost 

share sponsor. 

Senator DORGAN. I’m going to come back to that question of a 

cost share sponsor because one of the problems that we have is 

things don’t move forward unless there is a local sponsor. You 

know, we can gnash our teeth and wipe our brow and wring our 

hands about it, but unless there’s a local sponsor, we’re not going 

to make that kind of progress. 

Mayor Warford, you talked about the issue of the ice jams and 

reaching out to call in teams from across the country and so on. 

Can you give us a bit more information? 

What have you learned about that? Perhaps you and Mayor 

Helbling, what have you learned about that? I assume that the 

issue of ice jams will be with us in the future. 
272 

Who do you think should assume responsibility? You talked 

about trying to find some mechanism that would identify ice jams 

more quickly and the potential damage or danger from them. So 

what was it that you learned this spring with respect to ice jams? 

Mr. WARFORD. Thank you, Senator. The city of Bismarck is concerned with three things. 

No. 1, more adequate warning with regard to the rise of the 

water for the Fox Island area and South Bismarck and what we 

learned was that essentially there is no real data out there on ice 

jams. But our feeling is that there would be more monitoring of the 

water flow in the tributaries along with some devices along the 

Missouri River that we, as a community, could at least have more 

warning than just a few hours that the water is rising. 

You know, we were alerted by the citizens that the water was 

rising. And you know, we don’t have, you know, any means to do 

that. 

Our second, you know, point is warnings are our first. The second is, you know, to have an adequate response once there is flooding to look at, you know, a study so that we have a response. And 

maybe do we need some diking or a temporary diking plan. 

And the third thing the city of Bismarck is concerned with and 

what we’re talking about with the Corps are solutions. Are there 

solutions that can, you know, help mitigate it for the future? 

Senator DORGAN. I was on the eastern side of the State when I 

received reports that the consequences of a significant action with 

a certain ice jam could have caused massive flooding in a significant part of Bismarck. What would have been the worst, disastrous 

consequences? And how close were you to that last spring? 

Mr. WARFORD. We think we were pretty close, you know, to it. 

So when the ice jam was in place and the Corps ice jam expert 

came to Bismarck, really there’s not a lot of data out there on what 

to do with ice jams. The ice jam experts, they were talking about 

salting the ice jam and then talked about the demolition of it. And 

the decision was made to bring in the demolition team. 

We were prepared as the city of Bismarck for a worst case scenario had that, the blasting of the ice jam, not been successful for 

a rather significant flooding of Fox Island, Southport. We even had 

a contingency plan where we were going to put a temporary dike 

all the way down Washington Street to try to save property and 

possibly lives, you know, east of there. So our concern is that without the solutions that are being talked about with, you know, siltation and a lack of channelization and the flow of water into the 

Oahe that we’re going to be faced with this again. 

And so, we would like to see, you know, some solutions so that 

we’re not faced with that worst case catastrophic scenario. We were 

very, very concerned. We came very close in our opinion to, you 

know, having a major disaster had the blasting not worked. 

Senator DORGAN. How many were evacuated in the Bismarck/ 

Mandan area? 

Mr. WARFORD. I don’t know exactly. I think there were around 

200 in McLaughlin and in—— 

FEMALE SPEAKER 1 [off mic]. More than that. 

Mr. WARFORD. More than that, ok. There was more than that. 
273 

Senator DORGAN. Alright. Mayor Helbling, your response to that 

question? 

Mr. HELBLING. One of the things the city of Mandan learned 

through this experience is some type of computerized monitoring 

would be very helpful. One thing that we had a hard time doing 

is getting accurate information. And it seemed like Mayor Warford 

and I were constantly on the cell phone to each other. Have you 

heard anything? You know, what’s going on? 

And then it was the State. I mean, everybody seemed to be all 

over the place. We need some type of computerized monitoring of 

the river system, not only the Missouri, but the Heart River system. 

We think there needs to be more emphasis placed on the Heart 

River. This is the first time that I can ever remember where the 

Heart River went out well before the Missouri River went out. And 

I was down there and watching it. And the tremendous amount of 

debris that was coming out of the Heart was just coming over the 

top of the Missouri and laying and stacking up. And I don’t ever 

remember seeing that happen. 

Usually the Missouri River is open before the Heart opens up. So 

there was a tremendous amount of water and debris flowing down 

the Heart River. So we think more emphasis needs to be placed on 

the Heart River and the debris that’s laying in the Heart River. 

Some of the things that we’ve done, we’ve had some debriefing 

meetings after the flooding. And we’re working on some response 

times, at what elevation we should do what, you know, at x. We 

need to notify these people that there’s a concern. At y, this is what 

we need to do. 

So we’ve been working on some response times and hard communications within the county, the city and all of the Water Districts 

to see when we have to put specific plans in place. 

Senator DORGAN. Alright. Colonel Ruch, has the operation of the 

Garrison Dam in any way contributed to the flooding problems experienced here earlier this year? I guess the follow up question 

would be is the Corps looking at any changes to the operation of 

the Dam given the experiences this spring? 

Colonel RUCH. It’s interesting when you look at the different advice you get on how much water to release in some of these situations. You know, you’ll get advice that you need to release more to 

break the ice jams up. You’ll get advice that you need to go in the 

other direction and turn off the water, which is what we did last 

year. 

Senator DORGAN. Is that the first time since the Dam was built 

that the releases were shut down? 

Colonel RUCH. That is the first time ever that the average daily 

release has gone below, I believe, 4,100 cubic feet per second. And 

it was shut off completely. 

Yet, the real dilemma here is you have intakes upstream of Bismarck. And you need, at about 10,000 cubic feet per second you can 

have your intakes in the water. There are two powerplants and 

there is a municipal plant as well. When you cut the water below 

that then you have to shut down powerplants at a very cold time 

of the year. 
274 

There is a lot of consultation that goes on there. I’ll give you the 

book answer here. How has the operation of Garrison Dam contributed to the flooding problem? 

Garrison Reservoir provided significant flood damage reduction 

during this year’s spring event. Corps preliminary estimates of actual flood damages in Bismarck are in the range of $18 million. 

Damages would have been in excess of $100 million without the 

Dam in place. 

The regulation of Garrison reservoir significantly reduced the 

peak stage in the Bismarck area during the spring flooding event. 

This peak stage and discharge that occurred during the event was 

16 feet, had an estimated flow of 27,000 cubic feet per second. Had 

Garrison Reservoir not been in place the peak would have been approximately 82,000 cubic feet per second which corresponds to an 

open water stage of nearly 20 feet. 

It’s impossible to determine whether or not the ice jam would 

have formed without the reservoirs in place or if those stages had 

not formed. As far as looking at operations afterwards, we continue 

to monitor. But really the bottom line is you cannot predict the ice 

jams. 

Senator DORGAN. Sorry? 

Colonel RUCH. You cannot predict when an ice jam is going to 

occur. We were already dropping our water levels. So we will continue to monitor and control releases as best we can in every situation. We don’t think there’s an overall lesson learned here that tells 

us to do something different. 

Senator DORGAN. What mechanisms exist to try to detect the formation of an ice jam? Is there an opportunity in the early formation of an ice jam to address it as opposed to allowing it to—— 

Colonel RUCH. The ice tends to pile up very quickly. 

Senator DORGAN. Very quickly. 

Colonel RUCH. It’s not as if you can get in there. Where you’re 

talking about measures for dealing with ice jams, there are permanent structures that are very, very expensive. I doubt that we could 

ever get the cost benefit ratio required for that. There are places 

that have effective monitoring, early warning systems. 

I have a note and I can’t give you a lot of detail about it, but 

the State of Nebraska implemented an ice jam reporting network 

in 1993. Basically it tied together emergency management authorities just to keep everybody tied in and aware. 

Senator DORGAN. Do you have the authorities that you need at 

the Corps to deal with the Heart River? Mayor Warford mentioned 

Apple Creek. Do you have all the authorities you need in all those 

areas? 

Colonel RUCH. Yes. I believe we do have the authorities required, 

if requested under section 205 of title VII. 

Senator DORGAN. Let me go back to this question of the title VII 

programs, because I understand what you’re saying Mr. Royse that 

you’ve provided some funding and now the question is, is there a 

local sponsor for the next step. You’re saying the next step is a 

study. 

On the other hand the next step could be a study that results 

in debris removal or dredging 18 months from now. Seems to me 

that’s better than not having the local sponsor and 18 months from 
275 

now sitting at a table like this saying, you know what, we don’t 

want to have a study. Because, you know, the only way that the 

Corps can get from point A to point C is to complete point B as 

well because that’s a legal requirement for them. 

So I guess the question I ask is with a pretty complete understanding that debris removal is probably important here. The issue 

of dredging is important. I mean, that’s not a new issue for any of 

us. 

So how do we get to that point of actually getting the debris removed and the dredging that is required? Do you see, Mr. Gunsch 

or Mr. Royse, do you see at some point local sponsorship for this? 

Mr. GUNSCH. Senator Dorgan, the, you know, one advantage of 

having a joint water board is we are in position to be a local sponsor and speak on behalf on a number of county water boards. So 

it makes it advantageous that we have this board in place. And so 

we’ve been able to step up and be a local sponsor, not only on title 

VII, but a few other Corps programs to this area. 

But these are expensive cost share procedures. We have to rely 

upon the State water commission to provide us funds so we can become a local cost share. And how many times can we go back to 

the State water commission for funds to be a cost share partner on 

these programs is an issue. 

Senator DORGAN. No, it’s unlimited. 

The reason I say that is the State engineer is in the back of the 

room. I’ll invite him to say a word in a moment. He’s going to be 

testifying tomorrow when I’m holding a hearing talking about the 

Hazen/Stanton area and also down in the Linton area where we 

had some significant flooding events as well. 

Dale Frink is here. He is the State engineer. Would you pull a 

chair up here? As I said, you’re going to be testifying tomorrow, but 

would you also want to weigh in on the issue of local sponsorship? 

I know this is not putting a collar around your neck. But it is 

the case, as Mr. Royse has just indicated the State water commission plays a significant role in this. 

STATEMENT OF DALE FRINK, STATE ENGINEER, NORTH DAKOTA 

STATE WATER COMMISSION 

Mr. FRINK. Well, thank you, Senator. And, you know, in terms 

of the local sponsor, we really push to have a local representative 

be in charge. We will help fund them, if at all possible. 

But, you know, if you—we don’t like to, especially, you know, like 

Bismarck and Mandan, you know, they’re large communities and 

certainly are capable of managing something like this. But, you 

know, we do like to have a local sponsor so that they are in charge 

and the residents have a State agency come in and start dictating 

some things to them. 

Senator DORGAN. You see that the dilemma here is that, I think, 

there’s general understanding in this room that debris is a problem. Dredging, the lack of dredging is a problem. Both of which 

contribute to an event like this when you have very heavy runoff 

and an ice jam. It seems to me both the issue of debris and dredging are something that seems to be significant. 

So the question is how do you get to the point of having both addressed by the Corps? 
276 

Mr. FRINK. Well, there are really two issues here. One is funding. 

And I think that’s the easier part. 

And I think where Mike and Ken are getting a little, you know, 

concerned is that, you know, even if the State and locals funded it, 

we still need a permit from the Corps. And you know that could 

be a 2 year study. So you get—you’ve got two people here talking 

to contractors about when can we start. And then we talk to the 

Corps and say, well, we’ve got to do a 2 year study. And to, you 

know, with the result being a permit at the end. 

So it’s, you know, it’s kind of a timing thing. But the funding is 

probably easier than, you know, getting through the other type of 

things. 

Senator DORGAN. I still want to try to get to this understanding. 

How do you get from point A to point C without going through 

point B, if point B is a legal requirement? 

Mr. FRINK. Right. Well, in terms of a local sponsor, I guess I 

would encourage, you know, the two cities and the two counties to 

try to come up with a local sponsor. You know, the joint board is 

certainly one possibility. I know they don’t have a lot of money, 

but, you know, the State Water Commission could provide some 

money. 

And then you’d still have the local control that I think is really 

important here. 

Senator DORGAN. See how much I’m helping you here? 

At least I’m trying. Thanks, please stick around for a moment. 

Let me ask some questions that Mr. Narum submitted. I think 

Mr. Gunsch raised them, and we just will put them on the record. 

This from Gailen Narum, having lived on the river for many 

years some residents noted that the Corps of Engineers did not 

raise the river level since winter and again this spring to break up 

the ice flows as they have seen in the past. They’d like to know 

why. 

Colonel, can you respond to that? 

Colonel RUCH. Well, once again by the time these ice jams 

formed and the river was coming up I don’t believe that releasing 

more water is what anybody downstream really wanted at that 

point. We look at each one of these events and decide how to move 

forward. More water would have piled more ice up. 

Senator DORGAN. Is there a strategy the Corps has inevitably in 

the spring or the late winter and spring to release water to break 

up or in order to prevent jams from forming? 

The implication of this question suggests there’s always been a 

strategy. 

Colonel RUCH. The typical response to fight the stuff is perhaps 

to cut it back a little bit. And then once it stabilizes to release some 

more water to increase the channel underneath. You probably 

won’t find that in a manual, but that is kind of how it is done. But 

this ice piled up very quickly. 

Senator DORGAN. The other question was why is the Corps of Engineers relying on a gauge several miles upstream from the Fox Island area on which to base its response to ice jam flooding? Thus 

in their opinion the Corps of Engineers’ reaction was delayed and 

the State of North Dakota requested action to reduce releases from 

the Garrison Dam. 
277 

Again, that’s from the letter from Gailen Narum. Can you respond to that? 

Colonel RUCH. Not to that individual gauge. I will get an answer 

and put that into the testimony. But we rely on the gauges that 

are out there. 

I will get a better answer for you on that. 

[The information follows:] 

The Corps utilizes all of the USGS gages available on the Missouri River and tributaries when making reservoir regulation decisions. It is unlikely that an additional 

gage a few miles away from the existing gage would have resulted in any appreciable difference in our response or in the effects of our response given there is a 

two-day travel time from the dam to the Bismarck area. In addition, since ice jams 

can occur anywhere along the river it would be infeasible to site a gage or series 

of gages to cover all potential ice jam locations. 

Mr. FRINK. Senator Dorgan, just a couple of things. I think tomorrow at the hearings and today there’s going to be a commonality that we need a little more measurements along the river. 

And those are USGS gauges. And once they’re in place and then 

they’re available on the Internet for everybody to see. 

But I think we do need to look at installing some measuring devices both on the Missouri and the two locations that we’re talking 

about tomorrow. And I think we are already looking at that. And 

I think we can make that happen. 

Senator DORGAN. Alright, we’ll discuss that further. Some have, 

in testimony, mentioned various structures that might be advisable. I think Mayor Helbling you talked about structures on the 

Heart that you might see as advisable. 

By the way, I am going to ask about the jetty question in just 

a moment. But structures on the Heart, I think Mayor Warford, 

you also talked about a potential structure in Apple Creek, didn’t 

you? 

Mr. WARFORD. Yes. I’d like to maybe just address, you know, one 

other issue too with regard. I’m feeling a little target on my back. 

I don’t know if Mayor Helbling is as well. But you know the discussion of the local cost share on this. 

You know, I’m hearing that the river is on sovereign State land. 

And the Corps is in charge of the water. Yet when it comes down 

to, you know, mitigating some of the problems they’re looking at 

Mayor Helbling and me and our local communities to come up with 

the cost sharing money. And so, I hope that, at least my position 

is, is that, you know, we are maybe more victims rather than participants. I don’t know how the Mayor feels about that. 

But as far as the structures, if you’re referring to more gauges 

and more information, I would be a strong advocate of that. And 

would encourage the Corps to, you know, place gauges where the 

water rises so that we can make a direct decision that water is rising here, that there’s an imminent flood rather than having the 

gauge way up the river and you know, having the delay. You know, 

we’re you know, based as local leaders with, you know, coming up 

with a response we feel we would—we need to be notified and 

warned more quickly so that we can respond more quickly to the 

citizen’s needs. 

Senator DORGAN. My question, though, is I think you talked 

about the need to put up a temporary dike down Washington and 

so on. I also thought you mentioned the contribution of Apple 
278 

Creek to certain flooding activities that could be controlled with a 

structure. I thought Mayor Helbling talked about a potential flood 

control structure on the Heart. I didn’t quite understand what you 

meant. 

So, whenever you talk about flood control you talk about the 

things that can exacerbate flooding issues, the lack of dredging or 

debris and so on. Then you talk about the other issues of putting 

up structures that would probably control water. I’m asking the 

general question: are there structure questions here that are just 

tangential or are they central to any flooding issues? 

Mr. WARFORD. Well, the city of Bismarck feels that they would 

be a central issue. You know, I talked about in my testimony the 

2009 flood. But a catastrophic flood with a scenario where let’s say 

the blasting did not work and the Apple Creek let loose that there 

would have been more flooding in Bismarck. And we put up a temporary dike in the Cottonwood area. And we’re prepared to put up 

more which could maybe be a permanent dike. 

And we talked about other temporary dikes to mitigate that sort 

of doomsday scenario which, you know, could have taken place. So 

that’s what I was speaking of. We need guidance from experts that, 

you know, who claim they have models that can predict, you know, 

scenarios that would be greater flooding than we had in 2009. And, 

you know, what should we be doing as a community to respond to 

that situation? 

We’d like to be prepared for any and all situations if we could. 

Senator DORGAN. Mayor. 

Mr. HELBLING. Senator Dorgan, we have several areas along the 

Heart River where we’ve had massive erosion. And we feel it’s very 

important to take care of these areas or we’re going to start jeopardizing our Highway 6 Bridge. And then also east of the city, Sitting Bull Ridge, where the river turns there’s a secondary dike 

that’s in place. And it’s eroded all into the tow of the dike already. 

And we feel if we don’t get that repaired we’re going to wind up 

redirecting the channel of the Heart River and causing massive 

flooding in the southside of Mandan. So there are two areas of concern for us. 

Senator DORGAN. Can you respond, Colonel Ruch, to the issue 

Mayor Helbling has raised about the jetty? Mayor, do you want to 

repeat that issue that you had with the Corps? 

Mr. HELBLING. Well, we have that secondary dike system. 

There’s a secondary structure. And that that has massive erosion 

on it right now. 

And that’s an area where the Heart River turns. And there’s so 

much erosion there it’s already cored a way through the structure. 

And we’re very afraid that if we do not repair that area it’s going 

to change the river channel. 

The river is actually trying to change. It’s taken out that levee. 

And we’re very concerned with that area. And need to have it addressed in some manner. 

Colonel RUCH. I will answer that one. But also the one thing I 

wanted to point out earlier when we were talking about gauges upstream and where the gauge should be. You have to remember that 

the travel time for water from Garrison down to Bismarck is 2 

days. 
279 

So more data is better, but no matter what we do, the impact is 

11⁄2 to 2 days to when we make a change to what will be seen down 

here. On this actual issue, I just heard about this today. I got up 

here a little bit early and did a little touring around the area. 

So what I’ll promise to do is have somebody take a look at that 

and work with your folks and make sure we make a good assessment of the situation. I’m not even certain that it’s a Federal structure. But we will take a look at that and we will work directly with 

you and your people on that. 

Senator DORGAN. I don’t know if there are people in the room 

who are old enough to have been here, in Bismarck and Mandan, 

when there was chronic flooding with a rather wild Missouri River 

that in the spring would—there’s one. Anybody else? So there’s 

three or four, five people in the room who remember the days before there was a dam that controlled the river, before we had a series of stem dams on the Missouri River and controlled flows. 

I wasn’t here, but as I recall it was not terribly unusual to have 

massive flooding and a huge flood threat that would come running 

through these two cities and cause very serious problems. Then we 

had the building of this dam and the ability to somewhat control 

the Missouri River. 

So news of significant flooding threats in the Bismarck/Mandan 

region has been pretty unusual. That’s why what happened this 

spring was something that seemed kind of out of the ordinary. It’s 

why I asked the original question. What has caused this? 

If not a perfect storm, pretty close to a perfect storm in the sense 

a substantial snowfall. I think the key that, Colonel Ruch, you described was very fast melt that has, you know, unfortunately over 

in the Fargo area they had a relatively slow melt which I think 

saved them a lot of heartache and damage. Then the two ice jams 

which together apparently caused problems and it’s very hard to 

understand what an ice jam means and how to deal with it. 

So this was a very unusual situation. As I indicated wouldn’t 

have been so unusual 70 years ago, perhaps or 60 years ago, but 

it certainly is now. 

What I’d like to do for the next 15 minutes or so would be to invite some in the audience who wish to contribute to do so. If you 

have questions for the witnesses I’d be happy to entertain those as 

well. If you would stand up and state your name before asking the 

question I’d be happy to entertain questions for about 15 minutes. 

Yes, ma’am? 

Ms. BERGER. My name is Rosemary Berger. I reside at 2826 

Woodland Place which is down on Fox Island. My family was one 

of five that was rescued by a boat in the spring to get out. 

We had water over our mailboxes when they came by boat to get 

my family and my neighbors. I want to know. You’re saying that 

the Corps does not have some kind of a mean. But I’ve been told 

many times that they’ve raised the river after the first freeze so 

that water, the ice pushes up. It breaks that ice. 

This is the question that the Fox Island people are asking. Why 

wasn’t it raised after that first freeze? This ice that we had this 

winter because of the cold winter we had and the amount of snow 

and rain, whatever we had, was extremely thick. It was never 

raised like it normally is. 
280 

You’re saying this is in the spring that you didn’t raise it. No, 

we’re talking after the first freeze. This is the question that we 

have been asking. You did not answer it to that, if that. 

Senator DORGAN. Alright, Colonel, would you respond to that? 

Colonel RUCH. I’ll take you through a history of release. And 

minimum, once again, minimum release for intake and for the 

power plant is 10,000 cubic feet per second. 

Again we were coming out of drought conditions still conserving 

water. On March 1, Garrison releases were lowered from the winter release which is 16,000 cfs which is more upper level to 11,000 

cfs in preparation for the expected snow pack melt in North Dakota 

between Garrison and Oahe. 

The 11,000 cfs release rate was considered the minimum necessary to support the downstream intake. On the 23rd of March 

the river stage at the Bismarck began rising significantly. The Garrison, the releases were reduced from 11,000 cfs to 6,000 cfs since 

the downstream tributaries, particularly the Knife River were getting enough added flow but continued to support the intakes. 

On the 24th we dropped 4,000 cfs and Bismarck continued to 

rise, so later that day the decision was made to go to zero. During 

the period when the releases were cut to zero we did shut down 

power plants and we did take a municipal water intake out of service. 

So we were up at 16,000 cfs. And once again coming out of 

drought conditions we were within the acceptable range. I don’t 

know the actual numbers and whether that’s a good answer. But 

that’s how we were releasing. And we dropped to 11,000 cfs on 

March 1. 

Ms. BERGER. Ok. This last winter was a high measured amount 

of snowfall. We never had our January thaw, ok? It was always in 

North Dakota have had some kind of January thaw. 

So when we talk about this record snowfall. We were short by 

one inch. But any other time we would have had some kind of a 

thaw during the year. We never had that. 

But you’re still talking about March. I’m talking something that 

would have happened a year ago, when we had our first blizzard. 

We got into a freeze situation back maybe, November, December. 

Usually that river would rise and that didn’t happen. 

The year prior to this we had a substantial amount of rain that 

came from Montana. Montana had record amounts of snow. And I 

sat at your meeting that you had here a couple of months ago. And 

everybody at that meeting was praising the Corps of Engineers for 

raising the Lake Sacajawea. 

Well, you know what, I was angry at that meeting because I am 

one of these people that was affected. And you guys didn’t do anything to raise Sacajawea. That was Montana that did it. That was 

God that did it. It wasn’t you. Ok? 

So Sacajawea was raising. 

Senator DORGAN. Let me just make another point, however. We 

have been through a lengthy drought in which the main stem reservoirs have been largely depleted. Now in the last 2 years or so 

more water has come in. 

It doesn’t have anything to do with the Corps. It has to do with 

snow pack in the Rocky Mountains. 
281 

Ms. BERGER. Right. 

Senator DORGAN. That additional water has come in, and because the reservoirs have been so depleted they have not wanted 

to maximize the releases. That is what they have wanted to do is 

to restore additional water in those reservoirs. So they have not, 

as additional water has come in, increased releases just because 

they’re trying to make up what they should have conserved previously. 

Ms. BERGER. I’m not asking them to increase. I’m just asking 

them why didn’t they do what they had done on any normal year. 

They would have raised that, any normal year, to allow that water, 

that ice to break up so that the water could go underneath it. 

Senator DORGAN. I think you’re asking a question that I had 

asked the Colonel, and I think he answered it already. Is there a 

strategy, in terms of the management of the river flow that beginning early in a winter is designed to address the issue of ice? 

I’ve not ever heard of that, and you’re saying that that strategy 

does not exist? 

Colonel RUCH. It does not relate to that day. Once you get ice on 

the river then in the beginning you don’t release quite as much. 

Then you increase your releases to increase the channeling. 

In this case I think you hit on it very well because we have less 

of it, but there was more water, like you said before. It might not 

have been 20,000 cfs like years before. It was up at 16,000 cfs because that is what we could afford to do based on our annual operating plan to get the reservoirs right. 

Senator DORGAN. But that had nothing to do with what was happening this winter. That had to do with trying to refill a reservoir 

that had been depleted. Let me suggest something to you, ma’am. 

What I’d like the Colonel to do is to provide us with 5 years of 

releases/discharge by month for the past 5 years. Let’s all take a 

look at that and try to understand what was done by the Corps. 

[The information follows:] 

GARRISON DAM—AVERAGE DAILY RELEASE FOR MONTH (1,000 CUBIC FEET PER SECOND) 

Month 2004 2005 2006 2007 2008 2009 

January ............................................................................................................... 19.2 15.4 17.8 15.9 15.0 15.7 

February .............................................................................................................. 23.1 13.0 15.5 15.8 15.3 16.1 

March .................................................................................................................. 16.7 12.1 14.5 14.8 12.8 10.0 

April .................................................................................................................... 16.9 17.4 13.8 13.5 12.5 9.0 

May ..................................................................................................................... 15.8 16.5 15.3 13.3 12.9 13.3 

June .................................................................................................................... 18.0 15.0 19.8 16.0 14.3 15.9 

July ...................................................................................................................... 17.9 15.2 20.6 15.9 13.6 15.7 

August ................................................................................................................ 17.2 15.5 22.0 16.0 13.9 16.0 

September ........................................................................................................... 15.0 14.1 18.1 11.6 12.6 14.8 

October ............................................................................................................... 11.5 12.6 12.1 10.8 11.0 12.6 

November ............................................................................................................ 12.7 13.4 13.1 10.8 11.0 12.8 

December ............................................................................................................ 15.2 15.4 15.3 14.9 13.9 ........

Ms. BERGER. Ok. 

Senator DORGAN. And I appreciate your coming and raising those 

questions. 

Do others wish to ask questions? 
282 

Ma’am, if you would give me your name and address following 

the meeting because I will provide that for you when the Corps 

gets it to me. 

Ms. BERGER. Ok. 

Senator DORGAN. Alright. Sir. 

Dr. KRONBERG. I’m Dr. Scott Kronberg, a range scientist out at 

the Northern Great Plains Research Lab. But I like trees too, so 

I elected to live on Fox Island. 

And one concern I have after listening to the comments was assuming a study is done to allow for the removal of these Cottonwood trees and other debris and possibly dredged, how long is that 

study good for? I mean, can we remove debris for 5 years, 1 year, 

10 years? 

Senator DORGAN. Colonel? 

Dr. KRONBERG. It would be a bummer if we spent 2 years doing 

a study and get to remove debris for a year or dredge for a year. 

Colonel RUCH. Your question is a great one because that’s why 

we really have to do the study because all of these authorities 

allow us to go into a project and it is dredging. It doesn’t allow for 

follow on maintenance dredging. So you really have to make sure 

you’re solving a problem. 

Typically sedimentation occurs at a place in the river reach for 

a reason. So just dredging it out doesn’t mean it stays open. We 

really have to make sure that we’re addressing the bigger problem 

and not just getting to a quick solution that might last 6 months, 

might last a year. 

It’s a good question. 

Senator DORGAN. You know, the one thing I’m understanding 

from tonight’s discussion is that this is not a question of whether 

there needs to be action to deal with debris and siltation in this 

river. The question is how do we get that done. Right? 

Most of us understand even if we never run into this problem 

again with the ice jams and the perfect storm of massive snowfall, 

we’ve still got a problem with debris and siltation that ought to be 

taken care of. There is the point that’s raised that well, the river 

bottom belongs to the State and the management of the water belongs to the Federal Government and then the consequences of the 

problems are inherited by those who live in those areas. 

So somehow we need to get again, from point A to point C so that 

at point C we address this issue, siltation and debris. Then the 

other questions would be developed from whether it’s a title VII 

program or other program. Are there other devices, structures or 

other things necessary to try to provide added protection? 

Would local government want that to happen and initiate that as 

a plan? Because the Corps won’t come here and say here are the 

six things that you should have. Largely, it goes the other way. The 

local government, through a study says here’s what we think we 

need, and then you develop this criteria. 

Is there a Federal interest? Does it meet the cost benefit and so 

on? But you’ve asked a very important question. You don’t want to 

go 18 months down the road, finish a study, only to decide that 

there’s a very brief period in which you can do half the job. That 

doesn’t make any sense. 

Dr. KRONBERG. Right. 
283 

Senator DORGAN. Mr. Gunsch? 

Mr. GUNSCH. Senator, if I could address kind of the question relative to the debris removal. I agree from the standpoint and having 

discussed with the Fish and Wildlife Service and Game and Fish 

in the preparation of the flood hazard mitigation grant that this 

particular event was very unusual in the amount of debris and 

stuff that came out of the Heart River. The number of very large 

Cottonwoods, you know, 4 foot in diameter in some cases that were 

put down there. 

Is this going to happen again? It certainly could. But the debris 

removal, as we saw it from the three water resource districts, this 

is probably a onetime thing that we shouldn’t have to do for a long 

time again. As far as the dredging, that’s a larger perspective. And 

it may need to be done on a regular basis as was pointed out in 

the 1985 study. 

But again, as far as even the debris removal, there was discussion of even in the Flood Hazard Mitigation Grant as a 75/25 that 

the 25 percent cost share needed to come up with. And they were 

willing to consider that opportunity if they could move forward. But 

again, the permitting side of that has to be stepped through. 

Senator DORGAN. Alright. Yes, sir? 

Dr. HUGHES. My name is Jim Hughes, Dr. Jim Hughes. I’ve lived 

on the river, south of the ice jam in the Oahe bend area at the bottom of South 12, that area, since 1981. And I e-mailed your office 

the morning before the water began to rise. You could look back 

and see when that was. 

But I looked out the window and saw a 5 foot rise in the river, 

nothing on the news below the ice jam. I guess the point I want 

to make is that whatever was happening north when the river was 

blown, when the charges went off. I was downstream of that. 

The water was in my yard at the same level it was in 1997 when 

the river was running at 60,000 cfs. So I think what decompressed 

the river, ultimately was the river overtopping the oxbow that is 

just south of Bismarck/Mandan. And I think the 1988 flood plan 

from the Corps of Engineers did include an idea of having kind of 

a decompression channel that would take—that would go across 

that oxbow. 

I mean it seems to me that you can’t prepare for the amount of 

silt that’s going to arise and all of that. You have to somehow have 

a plan that allows for decompression to occur in an unnatural way 

or natural way. When you look at Google maps, Google sky, Google 

history, you can see where Sibley Island was in the past in the 

whole area to the west of us is underwater. I mean, Sibley Island 

apparently is an island because it was an island at a particular 

time of year. 

But the normal decompression or normal—it’s a quantitative 

change that happens and how the river is working when it reaches 

a certain level that overtops that oxbow south of Bismarck/ 

Mandan. 

Senator DORGAN. Thank you very much. Other observations or 

questions? Alright. 

What I would like to do is first of all I want to be helpful. I mean 

I’m chairman of the committee that funds the Corps of Engineers. 

I can’t create miracles, but I certainly can be helpful. 
284 

I want to be helpful in areas across the country and in areas 

where we’ve got, Lord knows, we’ve got a lot of water issues all 

across the United States that we’re working on. In this State, 

though, we had plenty of water issues to consume our time that 

were significant and potentially dangerous in many areas of the 

State. One of those areas was Bismarck. 

When I ask about Bismarck/Mandan, when I ask about the potential catastrophic result, had everything gone badly my assumption is there would have been massive damage, massive evacuation. 

This would have had a very, very significant impact on a region of 

our State. So coming that close to that significant an impact, the 

question is what can be done to try to reduce the possibilities of 

that happening again? 

I think from this discussion there are some obvious answers. 

There are also some which are not yet obvious that may come from 

some further inquiry. There will need to be, it seems to me, further 

discussions with the local government officials, the mayors, the 

State water commission and the Corps of Engineers so that we can 

understand what use of the authorities the Corps now has, and 

what could move us in the direction of getting these issues solved. 

Also, what additional authorities does the Corps need that I might 

be able to provide if they need additional authorities to address 

these issues. 

I’m pledged to do that, but I don’t necessarily know what that 

might be as a result of this hearing. I just wanted to hold the hearing to try to understand, as best I can, what really needs to be 

done. 

I think much of that is still going to rely on you, with the Corps, 

to tell us what we can do to be helpful. I think that there is a common determination. Nobody wants to go through this again. 

I think one thing I have learned is that there clearly needs to 

be more monitoring. That is a U.S. Geological Survey issue. We’ll 

work with them to see that we do that. 

I think the woman at the back of the room and the doctor talked 

about trying to understand what the river is doing. Well the more 

monitoring you have, the more information you’re going to have. 

With computer technology these days and the Internet, you have 

access, real time access, by everybody to that information which I 

think could be helpful. 

Colonel, would you wish to make any additional contributions tonight? 

Colonel RUCH. Just once again to thank you, Senator, for bringing us out here and letting us get a perspective from the people 

who live in this city. And these are good partners I’m sitting with 

up here. And we have met with many of their staff since the flooding and we will continue to do so to move forward. 

Thank you. 

Senator DORGAN. Ok. Mayors, did you want to make any additional comment? 

Mr. WARFORD. Thank you again, Senator, for the hearing. And 

I’ll go back to my original talking points. 

We want in the city of Bismarck, more warning. 

We would like to partner with whomever to get a more adequate 

response. We could up our game there. 
285 

And finally, long term solutions to the river are of strong concern 

to us. 

But thank you for the hearing. 

Mr. HELBLING. I’d also like to thank you for the hearing. I would 

like to thank the Corps that one of those water intake structures 

that the Colonel was talking about was the city of Mandan’s. And 

the city of Mandan shares that structure with Tesoro Refinery. 

And the Corps did work very well with the city of Mandan. How 

long? How much water supply do you have? When do we need to 

get more flows in there? How long can we cut it off? 

So I realize it was an unusual event. But I think under the circumstances everybody did work phenomenally together. Sure we 

can all do better, but I think we learned a great deal from this. 

And I think if we all work together there are good solutions on the 

table. 

Thank you very much. 

Senator DORGAN. Anyone else, any final comments? 

Mr. ROYSE. Senator, I would just say I’m pleased that you’re able 

to focus on the problem of cost shares as quickly as you did because 

that becomes a central problem we have. Trying to be a cost share 

partner, when we cannot control the costs or the time of the 

project, is a problem. 

The second thing I would like to say is I think the opportunity 

that we may have to influence how this management of the river 

is going to be performed through the MRAPS study is going to be 

important. And I’m hoping that the Corps will involve local and 

State officials in the process of some real formal processes, rather 

than just stakeholders meetings or task force meetings. But some 

process, however, has had real input from State and local officials 

on this process. 

We see this process through MRAPS as not only solving maybe 

a flooding issue, but balancing the benefits of that river system 

through the upper and lower basin States. Thank you. 

Senator DORGAN. Thank you very much, Mr. Royse. 

Mr. GUNSCH. Thank you very much, Senator, for providing the 

opportunity for everybody to communicate in this form. I think it’s 

advantageous from the water resource districts perspective to bring 

these things to the table and have the opportunity for the Corps 

to hear them. And I guess everybody always looks forward to working toward a solution. 

And with that I just want to thank you for the opportunity. 

Senator DORGAN. Dale, if you have any comments? Thank you for 

being here. I know I’ll be seeing you tomorrow morning as well. 

Mr. FRINK. Well, thank you. And I’d just like to say that, you 

know, we do work together very closely. And we work very hard 

at this. 

This was rather an unusual event. And it’s one that hasn’t happened in over years. And we learned some things. 

The Colonel mentioned the 10,000 cfs for example, labeled for the 

power plants. It used to be 8,000 cfs. But what is happening between Garrison and Price is the river is getting deeper. And that 

sediment is being deposited down here by Bismarck. And that’s 

causing you a problem. 
286 

So the river is getting deeper up in that end. And that’s why 

they ran into more problems that we realized they would. And so 

we learned something there. 

And we’ve learned a lot of things in some other areas. So, you 

know, hopefully next time we’ll be able to do it a little better. But 

it is a learning process. 

Even, you know, on Washington Street this gate was put in in 

1967. It’s the first time we used it. So you know you use things 

that infrequently, you know there is a learning curve involved here. 

So, ok, thank you very much. 

Senator DORGAN. Thank you. You mentioned the authorizing 

purposes study. When I drafted that and put that in the bill it was 

very controversial, as you can imagine. One State in particular 

downstream is having an epileptic seizure. 

But at any rate, it’s the right thing to do and an important thing 

to do. We have waited for longer than I have patience to, and finally we’re going to drive through this and get it done. 

I’m going to ask Justin Schardin, who works with me on water 

issues, to work with the two cities and the water districts and the 

Corps to see, on this specific set of issues, what more we can do, 

what you want us to do, and what you want to do for yourselves. 

Roger Cockrell and I will work on the subcommittee to evaluate 

what is possible to do in our subcommittee work beginning now in 

January. 

CONCLUSION OF HEARING

I want to thank all of you for being here. As I indicated tomorrow 

morning we’re going to have a hearing dealing with the Beulah/ 

Stanton/Hazen flooding issue. Then one dealing with the Linton 

area, just to try to get a sense of what happened there, and what 

might be necessary to try to mitigate that in the future. 

This hearing is recessed. 

[Whereupon, at 8:57 p.m., Wednesday, November 11, the hearing 

was concluded, and the subcommittee was recessed, to reconvene 

subject to the call of the Chair.] 

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