Prepared for: 

Great River Energy 

Stanton, North Dakota 

Proposal for Information Collection 

Stanton Station 

ENSR Corporation 

December 2006 

Document No.:10735-002-400 
Prepared for: 

Great River Energy 

Stanton, North Dakota 

Proposal for Information Collection 

Stanton Station 

_________________________________ 

Prepared By: Brian P. O’Neil 

_________________________________ 

Reviewed By: Jean Decker 

ENSR Corporation 

December 2006 

Document No.:10735-002-400 
ii December, 2006

Document No.: 10735-002-400

Contents 

1.0 EXECUTIVE SUMMARY........................................................................................................................... 1-1

2.0 INTRODUCTION........................................................................................................................................ 2-1

2.1 Goals, Process, and Timing of the Rule......................................................................................... 2-3

2.2 CDS Schedule................................................................................................................................. 2-3

2.3 Specific Goals of this PIC................................................................................................................ 2-4

2.4 Review of Document Organization................................................................................................. 2-4

3.0 SOURCE WATER BODY INFORMATION............................................................................................... 3-1

3.1 Source Water Body Physical Description and Flow Information ................................................... 3-1

4.0 TECHNOLOGIES, OPERATIONAL, AND RESTORATION MEASURES............................................. 4-1

4.1 In-place Technologies, Operational Measures............................................................................... 4-1

4.1.1 Review of Existing Technologies and Operational Measures.......................................... 4-1

4.1.2 Restoration Measures ....................................................................................................... 4-5

4.1.3 Performance Estimates ..................................................................................................... 4-5

4.2 Potential Technologies, Operational Measures, and Restoration Measures................................ 4-5

4.2.1 Review of Technologies .................................................................................................... 4-5

4.2.2 Review of Operational Measures...................................................................................... 4-9

4.2.3 Review of Restoration Measures ...................................................................................... 4-9

4.2.4 Estimate of Technology and Operational Measures Costs and Effectiveness ............... 4-9

4.2.5 USEPA’s Appraisal of Technologies............................................................................... 4-10

4.3 Selection of Proposed Technologies, Operational and Restoration Measures .......................... 4-10

5.0 HISTORICAL STUDY REVIEW ................................................................................................................ 5-1

5.1 Historical Biological and Physical Data .......................................................................................... 5-1

5.2 Assessment of Data Sufficiency ..................................................................................................... 5-4

6.0 AGENCY CONSULTATIONS ................................................................................................................... 6-1

6.1 Section 316(b)-Specific Consultations............................................................................................ 6-1

6.2 Other Relevant Consultations......................................................................................................... 6-1

7.0 PROPOSED COMPLIANCE APPROACH............................................................................................... 7-1

7.1 Outline of CDS Activities................................................................................................................. 7-1

7.2 Review of CDS Approach ............................................................................................................... 7-1

7.3 Schedule.......................................................................................................................................... 7-2

8.0 SAMPLING PLAN ..................................................................................................................................... 8-1
iii December, 2006

Document No.: 10735-002-400

List of Tables 

Table 1 Summary of the Circumstances at Stanton Station.................................................................... 4-2

Table 2 Estimated CWIS Performance Goal: 80 to 95 Percent Reduction in Impingement 

Mortality (IM) ................................................................................................................................ 4-5

Table 3 Primary Assessment of Mitigation Measures.............................................................................. 4-6

Table 4 Assessment of Data Sufficiency.................................................................................................. 5-5

List of Figures 

Figure 1 Site Location Map ........................................................................................................................ 3-3

Figure 2 Close-up View of CWIS Locations .............................................................................................. 3-4

Figure 3 Photographs of Cooling Water Intake Structure ......................................................................... 4-3

Figure 4 Fish Species Identified in the Garrison Reach, 1991 to 2003.................................................... 5-2

Figure 5 Summary of Fish Collected by NDG&F at Stanton Station 1997-2004 ..................................... 5-3

Appendices 

Appendix A – Technology Review 

Appendix B – EPA Cost Estimate 

Appendix C – Sampling Plan 

Appendix D – Bibliography of Sources Used for Source Water Body Review 

Appendix E – Agency Consultation Documentation 
1-1 December 2006

Document No.: 10735-002-400

1.0 EXECUTIVE SUMMARY 

Great River Energy’s Stanton Station (GRE) is subject to the impingement mortality performance goals under 

the Clean Water Act’s Section 316(b) Phase II Rule (rule). This Proposal for Information Collection (PIC) is 

developed as part of GRE’s obligations under the Phase II rule. 

The Stanton Station is located on the Missouri River about 15 miles downstream of Garrison Dam, which 

controls flow in the river. Mean annual flow at the dam is 21,041 cubic feet per second (cfs)1

 Stanton Station 

has one generating unit, with a rating of 188 MW. Normal plant operations utilizing the two main circulating 

water pumps and one auxiliary pump results in a flow of 240.3 cfs (107,800 gpm or 155 MGD). When the 

additional auxiliary pump is operating, the flow to the facility is 257.6 cfs (115,600 gpm or 166 MGD). Since 

average daily withdrawal exceeds the 50 MGD threshold, Stanton Station is subject to the Phase II Rule. 

However, reduction in entrainment is not a performance goal for these intakes since the intake rate is below 

the regulatory applicability threshold of 5 percent of the mean daily flow of the Missouri River at this location. 

U.S. Environmental Protection Agency (USEPA) identified the Stanton Station as being a facility that had to 

comply with both impingement and entrainment reduction requirements. USEPA has estimated that fine-mesh 

wedgewire screens installed near the shoreline will be effective at reducing impingement mortality consistent 

with the rule’s goals. USEPA also has assumed that entrainment reduction would be necessary and estimated 

that the screens could be installed at a total capital cost of $0.99 million. However, USEPA’s guidance states 

that if a facility determines it must only comply with impingement reduction requirements, the corresponding 

USEPA estimated cost can be calculated by dividing USEPA’s original cost estimate by 2.148. Dividing 

$0.99 million by 2.148 results in an USEPA cost estimate for the Stanton Station of $0.46 million. This is the 

cost estimate that should be used for comparison and cost-cost/cost-benefit analyses. 

This PIC provides a focused review of available mitigation technologies and concludes that no single 

reasonable measure exists to mitigate impingement mortality cost-effectively beyond that provided by the 

current configuration. In particular, each technology has either been found to be of limited feasibility and 

effectiveness or of “significantly greater” cost than the benefit to local fisheries that could be realized by its 

installation and operation. For this reason, GRE proposes to pursue the rule’s Compliance Option 5 based on 

the Cost-benefit test. GRE proposes to use existing data collected from the Missouri River and its environs as 

well as data that were collected through an Impingement Mortality Study to support the Comprehensive 

Demonstration Study (CDS). As a critical component of the CDS, potential retrofit technologies will be 

evaluated in detail to document both technical and economical feasibility. GRE believes that the application 

and outcome of the Cost-benefit test will demonstrate that the cost of installation of any of the available 

technologies would be significantly higher than any benefit that might result to the local fishery. 

The proposed component elements of the CDS are listed and a tentative schedule for the CDS completion and 

the North Dakota Pollutant Discharge Elimination System (NDPDES) permit renewal are defined within this 

PIC for Stanton Station. 

 

1

 Between 1993 – 2002. 
2-1 December 2006

Document No.: 10735-002-400

2.0 INTRODUCTION 

Stanton Station has one generating unit rated at 188 MW. This base loaded unit had an average annual net 

generation of 1,241,062 MWh from 1998-2003, which amounts to approximately an 80 percent capacity factor. 

Normal plant operations utilizing both main circulating water pumps and one auxiliary pump results in a flow of 

240.3 cfs (107,800 gpm or 155 MGD). When the additional auxiliary pump is operating, the total flow to the 

facility is 257.6 cfs (115,600 gpm or 166 MGD). 

The Stanton Station operates one generating unit that draws cooling water directly from the Missouri River. 

Because the total intake capacity of the Stanton Station exceeds 50 million gallons per day (MGD), an 

evaluation of impingement potential and reduction options is required. Reduction in entrainment is not a 

performance goal for these intakes since the intake rate is below 5 percent of the mean daily flow of the 

Missouri River at this location2

. 

The goals of this PIC for Stanton include the following: 

• Address the requirements of the Code of Federal Regulations (CFR), Title 40, Section 

125.95(b)(1); and 

• Facilitate the compliance process by explaining GRE’s proposed approach. 

40 CFR Section 125.95(b)(1) describes the PIC requirements as follows: 

You must submit to the Director for review and comment a description of the information you will use 

to support your Study. The Proposal for Information must be submitted prior to the start of information 

collection activities, but you may initiate such activities prior to receiving comment from the Director. 

The proposal must include: 

(i) A description of the proposed and/or implemented technologies, operational measures, and/or 

restoration measures to be evaluated in the Study; 

(ii) A list and description of any historical studies characterizing impingement mortality and 

entrainment and/or physical and biological conditions in the vicinity of the cooling water intake 

structures and their relevance to this proposed Study. If you propose to use existing data, you must 

demonstrate the extent to which the data are representative of current conditions and that the data 

were collected using appropriate quality assurance/quality control procedures; 

(iii) A summary of any past or ongoing consultations with appropriate Federal, State, and Tribal fish 

and wildlife agencies that are relevant to this Study and a copy of written comments received as a 

result of such consultations; and 

(iv) A sampling plan for any new field studies you propose to conduct in order to ensure that you 

have sufficient data to develop a scientifically valid estimate of impingement mortality and 

entrainment at your site. The sampling plan must document all methods and quality 

assurance/quality control procedures for sampling and data analysis. The sampling and data analysis 

methods you propose must be appropriate for a quantitative survey and include consideration of the 

methods used in other studies performed in the source waterbody. The sampling plan must include a 

description of the study area (including the area of influence of the cooling water intake structure(s)), 

 

2

 The mean average daily flow at the Bismarck USGS gauging station is 22,490 cfs. Five percent of the mean average daily flow is 

1,125 cfs which is more than four times the intake capacity of the Stanton CWIS, which is 258 cfs. 
2-2 December 2006

Document No.: 10735-002-400

and provide a taxonomic identification of the sampled or evaluated biological assemblages (including 

all life stages of fish and shellfish). 

The following tabulation provides the section of the PIC where each of the above mentioned regulatory 

requirements are presented. 

Regulatory Requirement PIC Section 

§ 125.95(b)(1)(i) – Review of Measures and Technologies 3.0 

§ 125.95(b)(1)(ii) – Historical Studies 4.0 

§ 125.95(b)(1)(iii) – Agency Consultations 5.0 

§ 125.95(b)(1)(iv) – Proposed Sampling Plan 7.0 

The Phase II Rule allows for significant discretion by the North Dakota Department of Health (NDDH) during 

the implementation process. In fact, the Rule allows for flexibility in the compliance approach taken at a facility 

by including several specific criteria associated with assessing compliance including: 

• Which species and life stages to base the compliance assessment; 

• Whether to base the assessment on numbers of individuals or biomass; 

• The specifics of estimating the Calculation Baseline condition; 

• The averaging period to use in estimating the Calculation Baseline or assessing compliance; 

• The ability to discount “unavoidable, episodic impingement or entrainment events” in the 

assessment of performance; 

• The specific design parameters (e.g., slot size) for the CWIS; 

• The need for, and nature of, peer review for assessment of restoration and/or monetized benefits; 

• The need for additional information collection to support the CDS; 

• The nature of the Technology Installation and Operation Plan; 

• The nature of Approved Technology (i.e., Compliance Option 4); 

• The definition of “significantly greater” under site-specific Best Technology Available (BTA) 

(Compliance Option 5); and 

• The timing of the component reports of the CDS. 

GRE believes that this level of discretion allows NDDH to oversee a focused and efficient compliance program 

to: 

• Assess the current performance of the CWIS and operation/restoration measures; 

• Review the alternative measures to determine those that are feasible and cost effective; 

• If appropriate, implement cost-effective measures; and 

• Develop a CDS within the context of one of the Rule’s Compliance Options. 

Toward this end, GRE has prepared this PIC that both addresses the requirements of the Rule and defines 

GRE’s recommended Phase II compliance program for the Stanton Station. 
2-3 December 2006

Document No.: 10735-002-400

2.1 Goals, Process, and Timing of the Rule 

The EPA has produced final regulations under Clean Water Act Section 316(b) that establish performance 

standards for existing CWISs for electricity generators using in excess of 50 MGD. The so-called Phase II Rule 

was published in the Federal Register on July 9, 2004, and became effective on September 7, 2004. 

The Phase II Rule calls for a 60 to 90 percent reduction in entrainment and an 80 to 95 percent reduction in 

impingement mortality from the “calculation baseline,” which is essentially the entrainment and impingement 

mortality rates at a similarly sized once-through shoreline CWIS with no impingement and/or entrainment 

reduction controls at the same location. These rates of protection are deemed by USEPA to be 

“commensurate with closed cycle cooling.” There is no requirement for power plants to adopt closed-cycle 

cooling. The Rule also provides for site-specific BTA in the event that site specific costs of compliance are 

“significantly greater” than either the costs estimated by USEPA for the station or for the monetized benefits of 

compliance at the station. 

The Rule allows for five different means of demonstrating compliance with the requirements of the Rule. 

• Compliance Option 1: Flow Reduction. Under Option 1(a) the facility owner can demonstrate that 

it uses closed-cycle cooling to show compliance with the Rule. Alternatively, if the through-screen 

velocity can be shown to be less than or equal to 0.5 ft/s, the performance goals relative to 

impingement mortality will be deemed to be met under Option 1(b). This latter approach does not 

address the potential entrainment performance goals, if applicable. 

• Compliance Option 2: Demonstrate that the current system achieves the relevant goals. Through 

the execution of a CDS, the plant can show that it is currently meeting the performance goals 

through some combination of technologies as well as operation and restoration measures. 

• Compliance Option 3: Demonstrate that a newly installed and operated system (i.e., technology 

and operation/restoration measures) will meet the goals. Again, through development of a CDS, 

the plant can design and implement a set of controls estimated to achieve the performance goals. 

• Compliance Option 4: Install and operate an approved technology. As part of the Rule, USEPA 

designated wedge wire screens in a riverine environment as an approved technology. Proper 

installation and operation of this technology will meet the goals of the Rule. NPDES Permit 

Directors have the ability to designate other technologies as “Approved.” 

• Compliance Option 5: Site-Specific BTA. Under this option, the facility can show that the actual 

costs of compliance are “significantly greater” than either the costs or benefits assumed by 

USEPA. Under this option, the plant is still required to pursue “cost-effective measures.” 

These various options are each associated with differing requirements relative to the CDS. Under Option 1(a), 

no CDS is required for assessment of impingement mortality, while, under some of the other options, relatively 

extensive analyses may be required along with submittal of several documents. 

2.2 CDS Schedule 

The Stanton Station’s current NDPDES permit, permit number ND-0000299, expires on December 31, 2006. 

Thus, the NDPDES permit renewal application was filed on or before June 30, 2006. Given that GRE’s ongoing Impingement Monitoring Study will not be concluded until July 2006, it was not possible to complete the 

CDS so that it could be submitted by June 30, 2006. The rule allows for request of a compliance schedule that 

partly decouples the NDPDES permit application and the CDS. GRE requested a compliance schedule that 

allowed delay in the submission of the CDS to as late as January 7, 2008. 
2-4 December 2006

Document No.: 10735-002-400

2.3 Specific Goals of this PIC 

The Stanton Station is affected by the impingement mortality performance goals of the Phase II Rule. The goal 

of this PIC is to provide the information necessary to demonstrate that it meets the requirements of the rule. 

2.4 Review of Document Organization 

Data on the physical configuration, flow, and water quality of the Missouri River are presented in Chapter 3.0. 

Discussion of existing and potential additional technologies and measures to mitigate impingement mortality 

are presented in Chapter 4.0. The nature of historical studies and the resulting data are summarized in 

Chapter 5.0. The potential utility of these data to support the CDS also is discussed. Chapter 6.0 presents a 

review of relevant agency consultations. GRE’s proposed compliance approach is summarized in Chapter 7.0. 

Chapter 8.0 discusses the approved sampling work plan. 

The PIC document also is supported by appendices that: 

1. Provide a general review of impingement mortality mitigation measures (Appendix A); 

2. Present USEPA’s estimated cost of compliance as summarized in the Phase II rule (Appendix B); 

3. Provide a copy of the Sampling Plan for the on-going monitoring program that is taking place at 

Stanton as well as two other neighboring power plants (Appendix C); 

4. Provides a bibliography of sources used for a review of the fisheries of the Missouri River including the 

station-specific data (Appendix D); and 

5. Provide copies of relevant written agency consultations (Appendix E). 
3-1 December 2006

Document No.: 10735-002-400

3.0 SOURCE WATER BODY INFORMATION 

This PIC provides NDDH with information regarding the circumstances that affect operation and performance 

of the current Stanton Station CWISs, the potential additional measures to reduce impingement mortality, and 

the compliance approach that GRE proposes to pursue. All three of these issues can be affected by the 

source water body flow rate as well as the physical configuration of the source water. GRE believes it may be 

very productive to consider these issues as part of the PIC; the rule anticipates their discussion either as a 

separate part of the CDS (i.e., the Source Water Body Flow Information – 40 CFR 125.95(b)(2)) or the 

NDPDES application itself (i.e., the Source Water Body Physical Data Report - 40 CFR 122.21(r)(2)). In order 

to facilitate NDDH evaluation of this data, GRE has slightly expanded the scope of the PIC to include the 

discussion here. 

The Phase II rule requires, as part of the NDPDES permit application submission, the following information to 

support Phase II compliance: 

1. A narrative description and scaled drawings showing the physical configuration of all source water 

bodies used by your facility, including aerial dimensions, depths, salinity and temperature regimes, and 

other documentation that supports your determination of the waterbody type where each CWIS is 

located; 

2. Identification and characterization of the source water body’s hydrological and geomorphological 

features, as well as methods you used to conduct any physical studies to determine your intake’s area 

of influence within the waterbody and the results of such studies; and 

3. Locational maps. 

3.1 Source Water Body Physical Description and Flow Information 

The Phase II rule requires consideration of Source Water Body Flow Information (40 CFR 125(b)(2)) under two 

circumstances: 

1. The CWIS is on a river or stream and the proportion of river flow taken in by the CWIS is an important 

potential threshold for the performance goals; and 

2. The CWIS is on a lake or reservoir and a proposed expansion of the CWIS flow might adversely impact 

the stratification of the water body. 

Historically, the Missouri River was a wide, meandering system, with abundant shallow channel borders, side 

channels, and back waters. Shifting sand bars and abundant debris provided ample habitat for numerous 

warm-water fishes and invertebrates, but also made navigation difficult or impossible in some areas. 

Channelization, particularly in the lower Missouri, has allowed commercial navigation but has eliminated 

sandbars and continuity with side channels and backwaters. In the upper Missouri, reservoir construction has 

created a series of deep-water habitats connected by inter-reservoir reaches that are significantly different in 

structure and ecology than the pre-impoundment system. The Garrison Dam was closed in April of 1953, 

forming Lake Sakakawea, which is the largest of the Missouri River mainstem reservoirs. At maximum surface 

elevation of 1,855 feet (above mean sea level), Lake Sakakawea has a storage capacity of approximately 

24.7 million acres feet and covers 385,615 (surface) acres. The section of the Missouri River located 

downstream of Lake Sakakawea and upstream of Lake Oahe is known as the Garrison Reach. 
3-2 December 2006

Document No.: 10735-002-400

The Stanton intakes are located on the Garrison Reach of the Missouri River, approximately 15 miles 

downstream of the Garrison Dam. The location of the Stanton Station relative to the Garrison Dam is 

presented on Figure 1. A close-up view of the GRE CWIS location and the CWISs of other nearby power 

plants is provided on Figure 2. Flow in this stretch of the river is totally regulated and will vary dependent on 

release rates from the dam. The closure of Garrison Dam, the fifth largest earthen dam in the U.S., triggered a 

shift in the nature of the Missouri River downstream of the dam. The average annual summer surface 

temperature in Lake Sakakawea is 19oC (66oF), which is colder than all other Missouri River mainstem 

reservoirs. The dam intake is located approximately 160 feet below the lake’s surface (at full pool). The water 

entering the Missouri River is therefore much colder than historic conditions, and remains cold even during the 

hottest summer months. Maximum water temperatures in the channel usually do not exceed 20oC (68oF) at 

Bismarck (70 miles downstream of Garrison Dam). 

The formation of Lake Sakakawea also resulted in a change in the sediment transport of the Missouri River. 

Historically a very silt-laden system, much of the bed load of fine material is now deposited in the upper 

reaches of Lake Sakakawea. Since the dam’s closure, approximately 37 percent of the reservoir’s gross 

storage capacity has been lost to sedimentation. Sedimentation has decreased below Garrison Dam and 

water clarity has increased. 

The main tributaries of the Garrison Reach of the Missouri River are the Knife and Heart Rivers and Painted 

Woods and Square Butte Creek. The Knife River joins the Missouri River from the west, only a short distance 

upstream of the Stanton Station. Local run-off into the Missouri River is sparse and seasonal so that the vast 

majority of flow through the Garrison Reach is due to release from the dam. Flow in the Garrison Reach has 

averaged 22,490 cfs from 1927 through 2001, as measured at the Bismarck USGS gauging station. Since 

construction of the dam, annual average flow has remained somewhat near this historical mean, though 

average monthly flows can vary widely due to release rates from the dam which vary dependent on hydropower considerations and attempts to balance or unbalance Lakes Sakakawea and Oahe, the next 

downstream reservoir. 
Riverdale

Underwood

Stanton

Pick City

Coleharbor

SITE LOCATION MAP

Figure 1

Great Rivers Energy Stanton Station

Proposal for Information Collection

USGS 15M Satellite Photo 01-01-2000

McLean, Mercer, and Oliver Counties

Garrison Dam

Garrison Dam Tailrace

NDG&F Sampling Location

Missouri River

Knife River

Confluence

Stanton Station

NDG&F Sampling Location

Lake Sakakawea

036 1.5 Miles Project No:

10735-002-400
April 2006

Project No: 10735-002-400

Figure 2

www.ensr.aecom.com

Scale: 1:10,000

Great Rivers Energy Stanton Station

Proposal for Information Collection

GlobeExplorer 1M Aerial 07/12/2003

Mclean and Mercer Counties, ND

Close-Up View of Stanton Station CWIS

0 0.125 0.25 0.5 Miles

Stanton Station

Leland Olds Station

(Basin Electric)

CWIS

NDG&F Sampling Area
4-1 December 2006

Document No.: 10735-002-400

4.0 TECHNOLOGIES, OPERATIONAL, AND RESTORATION 

MEASURES 

This section will review current and potential future technologies, operational, and restoration measures 

relative to their potential to meet the performance goals of the rule for Stanton Station cost-effectively. 

4.1 In-place Technologies, Operational Measures 

This section describes the current CWIS as well as its apparent performance relative to the performance goals 

of the Rule. 

A concise summary of the Stanton Station, its CWIS, and the available data is provided in Table 1. The details 

described in this table are presented in more detail below. 

4.1.1 Review of Existing Technologies and Operational Measures 

The Stanton facility has one generating unit rated at 188 MW. This base loaded unit had an average annual 

net generation of 1,241,062 MWh from 1998-2003, which amounts to approximately an 80 percent capacity 

factor. Circulating water for the unit is withdrawn through a shoreline intake structure. 

The intake structure consists of a small forebay with trash racks and traveling water screens. The forebay is 

about 53 feet long and 35 feet wide with an invert at Elevation 1,642.0 feet. An old deicing line is located 

along the walls of the forebay. This line is no longer in service, because spray headers at the inlet to the 

forebay now provide deicing water. A vertical divider wall that splits the forebay in half is located about 63 feet 

downstream from the forebay entrance. Trash racks are located 10 feet. downstream from this split on each 

side of the wall. The trash racks are 0.25-inch by 4-inch steel bars at 3-inch center-to-center spacing providing 

a 2.5-inch clear spacing. The trash racks are sloped at approximately 5.5V:1H. A monorail-mounted trash 

rake is used to clean the trash racks. A curtain wall with the bottom at Elevation 1,695.0 feet, which is 1.5 feet 

below the normal low water level, is located downstream of the trash racks. The curtain wall opening is 19 feet 

high. 

Two traveling water screens are located about 6 feet downstream of the curtain wall. The two screens are 

10 feet wide and have 0.25-inch square mesh. The screens are rotated twice a day for 45 minutes and 

cleaned by a high-pressure spray wash. Fish and debris removed from the screens are washed into a trough 

on the front side of the screens. Once in the trough, fish and debris flow out of the screen house and down a 

riprap drainage ditch back into the river. 

Two vertical, mixed-flow circulating water pumps are located downstream of the traveling screens at the end of 

two intake tunnels, one tunnel downstream of each screen and one pump in each tunnel. These tunnels are 

11.7 feet wide, 19.5 feet high and about 80 feet long. Each pump can provide a total flow of 122.5 cfs 

(55,000 gpm); combined pump flow is 222.8 cfs (100,000 gpm) to the condenser. There also are two auxiliary 

circulating water pumps located just upstream of the main circulating water pumps. Each of these pumps 

provides a flow of 17.4 cfs (7,500 gpm). During normal plant operations, both main circulating water pumps 

and one auxiliary pump are operated, resulting in a flow of 240.3 cfs (107,800 gpm or 155 MGD). When all 

pumps are operating, the flow to the facility is 257.6 cfs (115,600 gpm or 166 MGD). 

Warmed cooling water is discharged about 50 feet downriver of the intake through an open pipe. Discharge 

water is not typically recirculated because the flow of the river carries the heated water downstream. 
4-2 December 2006

Document No.: 10735-002-400

Table 1 Summary of the Circumstances at Stanton Station 

Setting Missouri River 

Capacity Factor N/A, Intake volume is < 5% of normal river flow 

Performance Goals Impingement Mortality only 

Summary of CWIS One shoreline intake located on the bank of the Missouri River. One unit produces appx. 

188 MW. Water is drawn from the river water surface. 10 feet long, by 17.5 feet wide 

forebays are at the end of a 53-foot channel with 0.25-inch traveling screens in place; 

approach velocity in channel app. 0.7 fps; through-screen velocity app. 1.4 fps. High 

pressure screen wash to trash collection basket and flow return to river over ground 

surface down riverbank. 

Number of Units 1 

Relationship to Baseline Condition Traveling screens are at the end of a 63-foot channel. 

Availability of Historical Data No recent site-specific IM data (On-going IM Characterization Study to be completed in 

June 2006); river fisheries studies; North Dakota Department of Game & Fish (NDG&F) 

fish collections since 1991. 

Applicability of Historic Data Significant amount of recent and historic data collected by NDG&F nearby identifies the 

species and numbers of fish expected in the area of the CWIS. 

USEPA Compliance Cost and 

Technology Estimates 

Installation of cylindrical wedgewire screens near shoreline for a total capital cost of 

$0.99 million and annualized cost of $298K/yr (adjusted cost for impingement only is 

$0.463 million). 
4-3 December 2006

Document No.: 10735-002-400

Figure 3 Photographs of Cooling Water Intake Structure 

Missouri River at Cooling Water Intake 

Intake Structure Channel
4-4 December 2006

Document No.: 10735-002-400

Opening to Screen House 

Traveling Screen Spray Wash Sample Collection Basket 
4-5 December 2006

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4.1.2 Restoration Measures 

No restoration measures have been performed. 

4.1.3 Performance Estimates 

Estimates of performance relative to the rule’s goals are contained in Table 2. The following paragraphs 

provide discussion of data used to estimate the performance based on the CWIS’s differences from the 

Calculation Baseline. 

Table 2 Estimated CWIS Performance Goal: 80 to 95 Percent Reduction in Impingement 

Mortality (IM) 

Estimated 

Reduction 

in IM 

IM - Difference from Baseline (%) Basis Notes 

1/4-inch mesh traveling screens 10 Engineering 

judgment 

High pressure wash and debris return, 

but not designed as fish return system 

Intake structure is at the end of a 

65-foot canal as opposed to flush 

against the river bank 

10 Engineering 

judgment 

With canal, fish have an opportunity to 

escape before the traveling screens 

Total IM Reduction 19 Not meeting goal 

4.2 Potential Technologies, Operational Measures, and Restoration Measures 

A summary of general technologies and operational measures available to address impingement mortality are 

presented in Table 3. This table presents the technology, estimated effectiveness in addressing impingement 

mortality, estimated technology cost, and notes on why or why not the technology was retained for further 

feasibility analysis. Appendix A provides a more in-depth general analysis of each technology and operational 

measure considered in Table 3. A listing of those technologies that were considered most promising for the 

Stanton Station is provided in Section 4.2.1. 

4.2.1 Review of Technologies 

The following criteria are used to assess the technologies and operational measures presented in Table 3: 

• Technical feasibility and reliability; 

• Effectiveness in meeting the Rule’s performance goals; 

• Costs relative to USEPA estimate developed as part of the Rule-making; and 

• Potential for other adverse effects. 
4-6 December 2006

Document No.: 10735-002-400

Table 3 Primary Assessment of Mitigation Measures 

Construction and Operation Issues2

BTA Alternative 

Cost 

(Capital 

plus O&M)1

Power 

Plant 

Efficiency 

Impact2

Station 

Outage with 

Construction

Navigation 

Effects 

Potential 

Clogging 

Potential 

Adverse 

Environmental 

Effects2 IM Benefits/ 

Effectiveness 

E Benefits/ 

Effectiveness 

Traveling Screen Modifications 

Modified traveling 

screens (dual 

flow) 

3 0 ** 0 0 0 

IM reduction if 

through screen 

velocity is reduced. 

None if standard 

screen mesh is used.

Modified traveling 

screens (Ristroph 

Screens) 

2 0 ** 0 0 0 

Effective IM reduction 

for many species. 

May not be effective 

for sensitive species 

None, if std. mesh 

size. 

Fine Mesh 

Screens on 

traveling screen 

system. 

6 0 ** 0 ** 0 

Effective with 

adequate fish 

handling system 

Potential entrainment 

reduction, but 

survivability uncertain 

even with fish 

handling system. 

Angled and 

modular inclined 

screens 

3 0 ** 0 0 0 

Potential 

impingement 

reduction for some 

species given 

effective fish return 

none 

Fixed Screening Devices 

Wedgewire 

Screens 2.5 0   **  * 

Effective 

impingement 

reduction if through 

screen velocity is 

appropriate. 

Potential for E 

reduction may 

depend on slot size, 

cross-flow current, 

productivity of 

surrounding area. 

Perforated Pipes not 

estimated 0 * * ** 0 

Some benefit 

possible because of 

absence of a 

confined channel in 

which fish can 

become trapped. 

none 

Barrier Net 0.5 0 0 ** * 0 

High if properly 

installed and wintertime impingement is 

low. 

None 

Aquatic Filter 

Barrier (e.g., 

Gunderboom) 

8 0 0 ** ** * IM reduction for all 

species 

E reduction for all 

species 

Porous Dike / 

Leaky Dam 4 0 * ** ** * 

High if through-dike 

velocities are low 

and/or behavior 

measures to 

minimize. 

Variable depending 

on size of gaps 

New Intake location 

Offshore Intake 

Structure (with 

wedgewire 

screen) 

4 0 ** ** * * 

Potential reduction 

for some species, 

depending on 

population density 

differences 

Potential reduction 

for some species, 

depending on 

population density 

differences 

Fish Diversion and Avoidance 

Diversion Devices: 

Louvers and Bar 

Racks 

1 0 0 * * 0 

Potential 

impingement 

reduction for some 

species given 

effective by-pass 

None 

Velocity cap on 

offshore intake 2 0 ** ** 0 0 

Potential reduction 

for some species, 

depending on 

population density 

differences 

Potential reduction 

for some species, 

depending on 

population density 

differences 

Behavioral 

Barriers: Strobe 

Lights, acoustic 

deterrent, bubbles, 

chains 

0.5 0 0 0 0 0 or * 

Potential 

impingement 

reduction for some 

species 

None 
4-7 December 2006

Document No.: 10735-002-400

Table 3 Primary Assessment of Mitigation Measures 

Construction and Operation Issues2

BTA Alternative 

Cost 

(Capital 

plus O&M)1

Power 

Plant 

Efficiency 

Impact2

Station 

Outage with 

Construction

Navigation 

Effects 

Potential 

Clogging 

Potential 

Adverse 

Environmental 

Effects2 IM Benefits/ 

Effectiveness 

E Benefits/ 

Effectiveness 

Flow Reduction

Variable Speed 

Pumps 2 * * 0 0 * 

IM reduction 

proportional to flow 

reduction. 

E reduction 

proportional to flow 

reduction, more 

effective during 

spawning period 

Capacity Factor 

Reduction variable ** 0 0 0 0 

IM reduction 

proportional to flow 

reduction. 

E reduction 

proportional to flow 

reduction, more 

effective during 

spawning period 

Evaporative 

Cooling Towers 42 ** ** 0 0 * IM reduction for all species 

E reduction for all 

species 

Dry Cooling Tower 60 ** ** 0 0 * IM reduction for all 

species 

E reduction for all 

species 

Increased Fish Population 

Restoration 0.05 to 1 0 0 0 0 0 Requires site-specific 

analysis 

Requires site-specific 

analysis 

Notes: 

1

 Costs do not include: a) thermal efficiency reduction or b) outage for construction. 

2

 Adverse effects: 

 0 = Negligible 

 * = Significant 

 ** = Potentially severe 

3 IM = Impingement Mortality of Aquatic Organisms 

4 E = Entrainment of Aquatic Organisms 
4-8 December 2006

Document No.: 10735-002-400

Site-specific technologies considered for the Stanton Station included: 

• Technology Alternative 1 – Traveling Screen Modifications 

1a – Dual Flow Screens (Impingement) 

1b – Ristroph Screens (Impingement) 

1c – Fine Mesh Screens (Impingement and Entrainment) 

1d – Angled and modular inclined screens (Impingement) 

• Technology Alternative 2 – Fixed Screening Devices 

2a – Wedgewire Screens (Impingement and possibly Entrainment) 

2b – Perforated Pipes (Impingement) 

2c – Barrier Net (Impingement) 

2d – Aquatic Filter Barrier (Impingement and Entrainment) 

2e – Porous Dike / Leaky Dam (Impingement and Entrainment) 

• Technology Alternative 3 – Offshore Intake (Impingement and Entrainment) 

• Alternative 4 – Fish Diversion and Avoidance 

4a – Louvers and Bar Racks (Impingement) 

4b – Velocity Cap (Impingement) 

4c – Strobe lights, acoustic deterrent, bubbles, chains (Impingement) 

• Technology Alternative 5 – Flow Reduction 

5a – Variable Speed Pumps (Impingement and Entrainment) 

5b – Capacity Factor Reduction (Impingement and Entrainment) 

5c – Evaporative Cooling Towers (Impingement and Entrainment) 

5d – Dry Cooling (Impingement and Entrainment) 

• Technology Alternative 6 – Restoration (Impingement and Entrainment) 

In Table 3, the capital costs for technology installation have been estimated for planning purposes. These 

costs are approximate but they do account for a number of site specific aspects. Table 3 also provides a 

qualitative discussion of potential operation and maintenance costs. Costs associated with facility downtime 

during construction also are likely but have not been estimated here due to the uncertainty in construction 

timing and the need to suspend operations at a given unit. In the execution of the Cost-benefit test, all of these 

issues will be revisited in a more formal fashion and their results expressed consistent with the requirement of 

the rule. 

The cost estimates for the various technologies were prepared by using the following resources: 

• USEPA Technical Development Document for the Final Section 316(b) Phase II Existing Facilities 

Rule, February 12, 2004. (EPA-821-R-04-007). 

• USEPA Technical Development Document for the Proposed Section 316(b) Phase II Existing 

Facilities Proposed Rule, April 2002. (EPA-821-R-02-003). 

• Cost estimates and/or installed costs for similar equipment obtained by ENSR from vendors and other 

operating facilities. 
4-9 December 2006

Document No.: 10735-002-400

Available costs were adjusted to account for size/capacity differences as follows: 

• Proportionally for components/equipment whose costs were judged to be proportional to size (e.g., 

pipe length); and 

• By the 6/10ths rule for those components whose costs were judged to not be directly proportional to 

size (e.g., pumps). 

The following factors were applied, where appropriate: 

• 10 percent Allowance for Indeterminants (AFI), a contingency on costs of the items included. 

• 30 percent Contingency, to address unforeseen items, especially with regard to a facility retrofit. 

• Escalation based on the time frame of the basis cost estimate. Since the basis cost year varied, 

estimated costs were escalated based on 3 percent annual rate of inflation. 

4.2.2 Review of Operational Measures 

Two operational measures are considered for the Stanton Station: more frequent rotation of the traveling water 

screens in order to reduce impingement mortality and flow reduction. These options are discussed fully in 

Appendix A. 

Evaporative cooling towers and dry cooling are much more costly than USEPA’s estimate for compliance and, 

therefore, will not be considered further. However, for reference, costs for these options are presented in 

Table 3. 

4.2.3 Review of Restoration Measures 

Restoration can be a very cost-effective measure for mitigating losses of aquatic organisms. Under some 

circumstances it may be possible to effect one-to-one replacement of important species or otherwise improve 

the ecosystem by an “out-of-kind” restoration, allowed by the rule. Examples of restoration methods generally 

include; fish restocking programs, habitat creation, habitat enhancement, and support of a state-sponsored 

restoration program. 

Of the available restoration measures, GRE favors those that have a direct impact on the species of concern 

(i.e., collaborative stocking programs with NDG&F) rather than habitat restoration which has a more tenuous 

connection to fisheries populations and is likely to be more costly. A more detailed discussion of restoration 

options is presented in Appendix A. 

At this time, the status of restoration under the rule is uncertain given pending court review. The final program 

costs as well as its effectiveness also are uncertain. However, given the relatively low expected levels of 

impingement mortality based on data collected to date through the Impingement Mortality study conducted by 

GRE, restoration is an attractive mitigation measure that should be retained for further evaluation. 

4.2.4 Estimate of Technology and Operational Measures Costs and Effectiveness 

The estimated costs and effectiveness of the evaluated technologies and operational measures are 

summarized in Table 3. 
4-10 December 2006

Document No.: 10735-002-400

4.2.5 USEPA’s Appraisal of Technologies 

As part of the Rule making process, USEPA developed an estimate of the cost of compliance with the Phase II 

Rule at each of the affected plants. These data are provided for the Stanton Station, with some slight 

modification to their presentation, as Appendix B. 

In the final Rule, USEPA does not present facility-specific estimates of the benefit of compliance to area 

fisheries. Instead, USEPA requires that the benefits of potential technologies and measures be estimated 

based on likely technology effectiveness and those benefits expressed as a monetized value using procedures 

defined in the Rule. The monetized value will be compared to the costs of the potential technology or measure. 

Under the Rule, if the costs are “significantly greater” than the estimated benefits, a site-specific BTA can be 

issued. 

USEPA identified the Stanton Station as being a facility that had to comply with both impingement and 

entrainment reduction requirements. USEPA has estimated that fine-mesh wedgewire screens installed near 

the shoreline and operated in conjunction with existing traveling screens would be effective at reducing 

impingement mortality consistent with the rule’s goals. USEPA also has assumed that entrainment reduction 

would be necessary and estimated that the screens could be installed at a total capital cost of $994,534 (see 

Appendix B). However, USEPA’s guidance states that if a facility determines it must only comply with 

impingement reduction requirements, the corresponding USEPA estimated cost can be calculated by dividing 

USEPA’s original cost estimate by 2.148. Dividing $0.99 million by 2.148 results in an USEPA cost estimate for 

the Stanton Station of $0.463 million. This is the cost estimate that should be used for comparison and costcost/cost-benefit analyses. 

4.3 Selection of Proposed Technologies, Operational and Restoration Measures 

Several technologies have the potential to be effective at reducing impingement mortality. These range in 

complexity and cost from behavioral barriers to installation and optimized operation of Ristroph-type buckets 

on the traveling screens. A total of six alternatives that included eighteen options have been screened based 

on their technical feasibility, effectiveness and relative costs. This evaluation is included as Appendix A and 

is summarized on Table 3. 

Based on this screening assessment, the following potential technologies or measures are proposed for 

further evaluation in the CDS: 

• Technology Alternative 1 – Traveling Screen Modifications 

1a – Dual Flow Screens 

1b – Ristroph Screens 

• Technology Alternative 2 – Fixed Screening Devices 

2a – Wedgewire Screens 

2c – Barrier Net 

• Technology Alternative 4 – Fish Diversion and Avoidance 

4c – Strobe lights, acoustic deterrent, bubbles, chains 

• Technology Alternative 5 – Flow Reduction 

5a – Variable Speed Pumps 

5b – Capacity Factor Reduction 

• Technology Alternative 6 – Restoration 
5-1 December 2006

Document No.: 10735-002-400

5.0 HISTORICAL STUDY REVIEW 

Relevant historic impingement and entrainment studies have not been conducted at Stanton or at other, 

similar power stations in the area. An impingement mortality study was conducted at Stanton and two other 

nearby power stations and was completed in July 2006. The multi-station impingement mortality study work 

plan is provided in Appendix C. Several studies of the Missouri River have been completed and are 

described in the following sections. The ability of the combined data set to support the requirements of the 

Phase II rule, in particular the Impingement Mortality Characterization Study (IMCS), is discussed in 

Section 4.2. GRE does not propose to collect additional source water body data. 

5.1 Historical Biological and Physical Data 

The Stanton CWIS is located on the Garrison Reach of the Missouri River. This reach has been studied 

thoroughly with regard to aquatic species for many years by Federal and State agencies as well as other 

independent researchers. Twenty reports on various aspects of the status of the fishery along the Garrison 

Reach have been researched during the development of this PIC (a bibliography of these sources is provided 

in Appendix D). Most significantly, North Dakota Game and Fish Department has conducted fish population 

studies in the Garrison Reach since 1991. These studies involved semi-annual fish collection at seven 

locations in the Garrison Reach. One of these collection locations is offshore of the Great River Energy (GRE) 

Stanton Station’s cooling water outfall. The location of the North Dakota Game and Fish Stanton sampling 

point is identified on Figure 2. 

Figure 4 presents a complete list of all the fish species identified in the Garrison Reach from 1991 through 

20033

. Figure 5 presents the number of each species identified at the Stanton Station by North Dakota Game 

and Fish during sampling events in summer and in fall from 1997 through 2004. The second condition listed 

above will be addressed by the data collected by North Dakota Game and Fish since it is likely that fish 

populations and movement were at their highest levels in the months that were sampled. The impingement 

characterization study will provide additional species occurrence data for the entire year. The existing data 

have been used to identify the species of fish likely to be found during the impingement characterization study 

and will be utilized to analyze the potential impact of impingement in the study report and during completion of 

the CDS. Additional data collected by North Dakota Game and Fish and other organizations will be 

incorporated into the study as soon as they are made available. 

 

3

 North Dakota Fisheries Investigations, Aquatic Investigations of the Missouri Mainstream in North Dakota, by Jeff Hendrickson, North 

Dakota Game and Fish Department, March 2004. 

5-3 December 2006

Document No.: 10735-002-400

Figure 5 Summary of Fish Collected by NDG&F at Stanton Station 1997-2004 

Total Number of Each Fish Specie Present at Stanton Sampling Site 

NDG&F Sampling 1997 – 2004 

 Summer Fall 

Bigmouth Buffalo 15 160 

Black Bullhead 0 0 

Black Crappie 0 0 

Bluegill 0 0 

Blue Sucker 15 8 

Brown Trout 2 25 

Brook Stickleback 0 0 

Burbot 1 6 

Common Carp 84 125 

Channel Catfish 11 7 

Cisco 0 7 

Common Shiner 9 0 

Cutthroat Trout 16 5 

Emerald Shiner 39 142 

Chinook Salmon 15 7 

Fathead Minnow 0 1 

Freshwater Drum 5 5 

Goldeye 11 8 

Golden Shiner 0 0 

Johnny Darter 4 39 

Largemouth Bass 0 0 

Longnose Dace 0 1 

Longnose Sucker 100 103 

Northern Pike 25 8 

Orange Spotted Sunfish 0 0 

Paddlefish 3 0 

Rainbow Smelt 3 14 

Rainbow Trout 1 4 

River Carpsucker 330 295 

Smallmouth Buffalo 8 43 

Sauger 38 34 

Shorthead Redhorse 140 65 

Smallmouth Bass 9 7 

Shortnose Gar 3 7 

Shovelnose Sturgeon 4 7 

Spottail Shiner 0 3 

Walleye 264 203 

White Bass 50 38 

White Sucker 389 409 

Western Silvery Minnow 0 1 

Yellow Perch 0 3 

Totals 1,594 1,790 
5-4 December 2006

Document No.: 10735-002-400

The data collected by North Dakota Game and Fish as well as other researchers provide a relevant and 

ongoing characterization of the biological conditions and populations in the river near the intake structure of the 

Stanton power plant. The data are representative of current conditions and were collected using appropriate 

QA/QC procedures by agencies of the State of North Dakota. The Impingement Characterization Study as 

described in this PIC will comply with the third condition listed above and will complete the data set required by 

the rule. The IM study work plan is included in Appendix C. 

In 1974 and 1978, studies were conducted by Dr. Joe Neel with the University of North Dakota at the request 

of Basin Electric. The studies were intended to determine the temperature, chemical and biological effects of 

the water withdrawal and discharge from the Leland Olds Station just downstream of the Stanton Station. The 

1978 study, “Life in the Missouri River with Warming by 676 Megawatts Gross Steam Generated Power 

Production”, conducted fish sampling at the intakes, at the screens and wash water return and downstream of 

the discharge. Observations and sampling were mainly conducted in the late spring and summer months. 

Fifteen species of fish were observed or captured and the text of the report states that primarily bullhead 

fingerlings were found in the intakes and on the intake screens. The data presented in the report indicated that 

during fifteen days of sampling the traveling screens, 56 fish were recovered from intake screen washings and 

44 of these fish were black bullheads. River temperatures were slightly elevated in the vicinity of the discharge 

but the report states that they were not as high as temperatures found naturally in other stretches of the river. 

The report states that “the intake does not appear to pose a great threat to adult fish, but is more hazardous to 

young, particularly to schooling bullheads.” 

A review of a recent publication, “Distribution and habitat use of sturgeon chubs (Macrhybopsis gelida) and 

sicklefin chubs (M. meeki) in the Missouri and Yellowstone Rivers, North Dakota” (Everett, Scarnecchia and 

Ryckman, 2004) indicated that, in recent sampling studies of the Missouri River in the vicinity of the station, 

there were no chubs of either species collected. The authors of the study concluded that this was probably due 

to significantly deeper, faster and clearer water than was found in the other river segments studied. 

5.2 Assessment of Data Sufficiency 

Among the requirements of the CDS is the performance of a study of impingement mortality. The results of this 

study may be used to assess the performance of the current CWIS as well as evaluate additional potential 

technologies and measures. The Rule sets out specific requirements for this study and addressing these goals 

is an important aspect of the PIC. The Rule anticipates that it may be possible to base the CDS completely or 

in part on existing data. For these reasons, Table 4 presents the specific data requirements for the study and 

reviews the relevance of available data to these requirements. The table also comments on the potential 

necessity of additional field data. 
5-5 December 2006

Document No.: 10735-002-400

Table 4 Assessment of Data Sufficiency 

Rule Citation Requirement 

Historical 

Data 

Source Notes 

Additional 

Data 

Proposed? 

125.95(b)(3)(i) Taxonomic identifications of all life stages of 

fish, shellfish, and any species protected 

under Federal, State, or Tribal Law (including 

threatened or endangered species) that are in 

the vicinity of the cooling water intake 

structure(s) and are susceptible to 

impingement and entrainment. 

SiteSpecific; 

Regional 

Literature 

Surveys of extant 

populations and 

reference 

materials can be 

used to assess 

historical trends 

and current 

populations in the 

area. 

No 

125.95(b)(3)(ii) A characterization of all life stages of fish, 

shellfish, and any species protected under 

Federal, State, or Tribal Law (including 

threatened or endangered species) identified 

pursuant to paragraph (b)(3)(i) of this section, 

including a description of the abundance and 

temporal and spatial characteristics in the 

vicinity of the cooling water intake 

structure(s), based on sufficient data to 

characterize annual, seasonal, and diel 

variations in impingement mortality and 

entrainment. 

SiteSpecific; 

Regional 

Literature 

Surveys of extant 

populations and 

reference 

materials can be 

used to assess 

historical trends 

and current 

populations in the 

area. 

No 

125.95(b)(3)(iii) Documentation of the current impingement 

mortality and entrainment of all life stages of 

fish, shellfish, and any species protected 

under Federal, State, or Tribal Law (including 

threatened or endangered species) identified 

pursuant to paragraph (b)(3)(i) of this section 

and an estimate of impingement mortality and 

entrainment to be used as the calculation 

baseline. Impingement mortality and 

entrainment samples to support the 

calculations required in Section 

125.95(b)(4)(i)(C) and 125.95(b)(5)(iii) of the 

Rule must be collected during periods of 

representative operational flows for the 

cooling water intake structure and the flows 

associated with the samples must be 

documented. 

None Historic rates of 

impingement 

mortality have not 

been quantified. 

Yes – Current 

year-long IM 

Characterization Study 

will conclude 

in June 2006. 

Results will be 

incorporated 

in CDS 

documents. 

In summary, GRE believes that the wealth of data available on the Missouri River and its environs will support 

the goals of the Rule in general and the IMECS in particular. 
6-1 December 2006

Document No.: 10735-002-400

6.0 AGENCY CONSULTATIONS 

The Rule requirements for the PIC ask for a summary of any past or ongoing consultations with appropriate 

federal, state, and Tribal fish and wildlife agencies that are relevant to this Study and a copy of written 

comments received as a result of such consultations. GRE believes that the goal of this summary is to provide 

NDDH with full perspective on the historical permitting of the CWIS as well as any potential concern by 

relevant fisheries management or other natural resources agencies. Copies of correspondence with the 

agencies are presented in Appendix E. 

6.1 Section 316(b)-Specific Consultations 

A draft of the Impingement Mortality Sampling Plan was submitted to NDDH and the NDG&F in May 2005 and 

discussed in a meeting later that month. Comments were received and incorporated into the Plan. An approval 

from NDDH was received in August 2005 and is provided in Appendix E. 

The Impingement Mortality Study was completed in July 2006. A meeting was held with NDDH, NDG&F and 

U.S. Fish and Wildlife Service (USFWS) representatives in October 2006 to review the study data and discuss 

its implications for 316(b) compliance. 

6.2 Other Relevant Consultations 

GRE has communicated on several occasions with NDG&F relative to impingement of fisheries at Stanton 

Station and the status of the Missouri River fishery in the general area of the Stanton Station. GRE also has 

consulted with the USFWS with regard to Threatened or Endangered species in the vicinity of the Stanton 

Station CWIS. These consultations were taken into account in the formulation of the Impingement Mortality 

Sampling Plan that is described in Section 6 and presented in Appendix C. 
7-1 December 2006

Document No.: 10735-002-400

7.0 PROPOSED COMPLIANCE APPROACH 

GRE’s proposed approach to Phase II Rule compliance is a BTA determination based on Compliance 

Option 5 – actual costs of compliance are “significantly greater” than the benefit to be gained from installation 

of any of the appropriate technologies. 

7.1 Outline of CDS Activities 

According to 40 CFR Section 125.95(b), the “Comprehensive Demonstration Study is to characterize 

impingement mortality and entrainment, to describe the operation of your cooling water intake structures, and 

to confirm that the technologies, operational measures, and/or restoration measures you have selected and 

installed, or will install, at your facility meet the applicable requirements of §125.94.” As outlined in Section 

125.95(b), a CDS intended to support Compliance Option 5 based on the Cost/Benefit test must include: 

• Proposal for Information Collection (PIC) 

• Source Waterbody Flow Information 

• Impingement Mortality and/or Entrainment Characterization Study (as appropriate) 

• Technology Installation and Operation Plan (TIOP) (if appropriate) 

• Restoration Plan (if appropriate) 

• Information to support site-specific determination of best technology available for minimizing adverse 

environmental impact 

o Comprehensive Cost Evaluation Study 

o Valuation of Monetized Benefits of Reducing IM&E 

o Site-Specific Technology Plan 

• Verification Monitoring Plan 

GRE will prepare each of these documents and submit them to NDDH for review. 

7.2 Review of CDS Approach 

The CDS approach for the Stanton Station includes providing the required information and submittals so that: 

• Rates of impingement mortality will be quantified for 1 year. 

• The Impingement Mortality Characterization Study will summarize the full range of available data in 

order to estimate the extent of mitigation from the Calculation Baseline as well as estimate the current 

losses. 

• Existing technologies and operational measures to achieve the impingement mortality goal will be 

described and their effectiveness estimated based on currently available data. The assessment will 

consider the feasibility and reliability of the technology as well as its likely effectiveness and cost. 

• Alternative technologies or measures to control impingement mortality will be evaluated for 

effectiveness, feasibility, and costs. GRE believes that each alternative technology and measure will be 

shown to be significantly more costly than the USEPA estimate of compliance costs at the Stanton 

Station. For this reason, the site-specific BTA (i.e., Compliance Option 5) will be pursued on the basis of 

the Cost/Benefit test. 
7-2 December 2006

Document No.: 10735-002-400

• The technology assessment and discussion of the installation and operation of selected measures will 

be presented in the Site-Specific Technology Plan, and/or the Restoration Plan, as appropriate. 

• The nature of the proposed ongoing compliance activities including their timing will be outlined in the 

Technology Installation and Operation Plan. 

7.3 Schedule 

The following is a conservative schedule for the Stanton CDS: A compliance schedule will be requested to 

postpone submittal beyond NDPDES permit renewal, as allowed by the regulations. 

• Submit NDPDES permit renewal application and request 316(b) compliance extension to NDDH by 

June 30, 2006; 

• Develop Impingement Mortality Characterization Study Report by September 30, 2006; 

• Submit PIC to NDDH by December 15, 2006; 

• Receive approval of PIC from NDDH by January 31, 2007; 

• Submit the Technology Installation and Operation Plan (TIOP) and Restoration Plan (if appropriate) by 

June 30, 2007; 

• Submit information to support the site-specific best technology available (BTA), including the 

Comprehensive Cost Evaluation Study (CCES), Valuation of Monetized Benefits of reducing IM, and 

the Site-Specific Technology Plan (SSTP) by July 31, 2007; 

• Meet with NDDH to discuss submittals and proposed BTA by September 1, 2007; 

• Submit the Verification Monitoring Plan to NDDH by September 30, 2007; 

• Approval of Verification Monitoring Plan by NDDH by October 31, 2007; 

• Implement Verification Monitoring Plan by November 30, 2007; 

• Receive modified NDPDES permit from NDDH by December 31, 2007. 

GRE notes that this schedule is an approximation but expects to achieve full compliance well before the 

maximum allowed extension deadline of June 2009. 
8-1 December 2006

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8.0 SAMPLING PLAN 

The Sampling Plan that was implemented at the Stanton Station in June 2005 is included as Appendix C to 

this PIC. It was submitted to NDDH as a separate document in May 2005 for preliminary approval. Approval 

was provided by NDDH in August 2005. A copy of the approval letter is provided in Appendix E. The 

sampling program was competed in July 2006. 
December 2006

Document No.: 10735-002-400

Appendix A 

Technology Review 
December 2006

Document No.: 10735-002-400

General Technology Overview 

This section provides a general review of a comprehensive list of potential mitigation methods to reduce 

impingement mortality and entrainment. The nature of the technology is briefly reviewed and its approximate 

costs4

 are presented. The effectiveness under the conditions at the Stanton Station is discussed and factors 

affecting performance, reliability, and other environmental issues are reviewed. In addition to CWIS 

technologies, facility operation and restoration measures are considered. 

The following list of CWIS alternatives have been evaluated in this screening assessment: 

• Technology Alternative 1 – Traveling Screen Modifications 

1a – Dual Flow Screens (Impingement) 

1b – Ristroph Screens (Impingement) 

1c – Fine Mesh Screens (Impingement and Entrainment) 

1d – Angled and modular inclined screens (Impingement) 

• Technology Alternative 2 – Fixed Screening Devices 

2a – Wedgewire Screens (Impingement and possibly entrainment) 

2b – Perforated Pipes (Impingement) 

2c – Barrier Net (Impingement) 

2d – Aquatic Filter Barrier (Impingement and Entrainment) 

2e – Porous Dike/Leaky Dam (Impingement and Entrainment) 

• Technology Alternative 3 – Offshore Intake (Impingement and Entrainment) 

• Technology Alternative 4 – Fish Diversion and Avoidance 

4a – Louvers and Bar Racks (Impingement) 

4b – Velocity Cap (Impingement) 

4c – Strobe lights, acoustic deterrent, bubbles, chains (Impingement) 

• Technology Alternative 5 – Flow Reduction 

5a – Variable Speed Pumps (Impingement and Entrainment) 

5b – Capacity Factor Reduction (Impingement and Entrainment) 

5c – Evaporative Cooling Towers (Impingement and Entrainment) 

5d - Dry Cooling (Impingement and Entrainment) 

• Technology Alternative 6 – Restoration (Impingement and Entrainment) 

 

4

 This report presents estimates of the capital costs of potential mitigation measures as a means of illustrating their potential costeffectiveness. The estimates should be considered approximate and final costs may vary by as much as factor of two or more. Cost 

estimates for mitigation measures do not account for facility down-time associated with construction or operation/maintenance. These 

costs will be estimated with input from GRE and included in the final CDS document especially in the information to support the Sitespecific BTA. Costs will be annualized according the procedures defined in the rule. 
December 2006

Document No.: 10735-002-400

Technology Alternative 1 – Traveling Screen Modifications with Fish Removal and Return System

• 1a – Dual Flow Screens 

Description:

With dual-flow, single-exit screen, incoming water is filtered with both the upward and downward moving parts 

of the screen, and the water flows toward the pump from the interior through the open side of the screen. The 

screen faces are oriented parallel to the direction of flow. If space is available, the screen length can be 

extended outward such that the area of the screens can be greater than the area of a conventional flowthrough screen in the same location. Therefore, the dual-flow design has the potential to reduce throughscreen velocity compared to flow-through (single entry, single exit) design. 

The dual-flow design also provides an advantage of eliminating the potential for debris that is stuck on the 

screen to be dislodged in the downstream side of the screen. This feature has an added benefit of lower wash 

water pressure requirements. 

Technical Feasibility and Reliability:

For retrofit applications, the space available to install may be limited by the existing structure (trash racks 

upstream and pump vault downstream) and water body constraints (navigation). Such limitations may limit the 

ability to increase screen surface area, thereby limiting the ability to reduce through-screen velocity. 

Hydraulic issues with a dual-flow screen are commonly encountered. One of the common limitations with dualflow screens is the flow disruption that is caused by the two 90-degree turns that cooling water must undergo 

to pass through the system. These issues can be minimized (but not eliminated) by proper hydraulic analysis 

and design. 

Dual flow screen are commercially available and have been in use for years. 

For the site-specific evaluations, the dual-flow screens with conventional mesh are assumed to provide 

adequate screen area to reduce through-screen velocity to 0.5 feet per second (ft/s). Otherwise, there would 

be no advantage to changing from a through-flow screen to a dual-flow screen. In some cases, the required 

screen area may result in the need for additional new intake structures to accommodate the screens. 

Cost Considerations:

The cost of dual-flow screens is expected to be up to 20 percent higher than comparable through-flow 

screens. 

Effectiveness:

Dual flow screens have the potential to reduce through-screen velocities and therefore impingement mortality, 

with the addition of an appropriate fish handling and return system. However, depending on the proximity of 

other screens and structures, the full screen area may not be effectively used, and through screen velocities 

on parts of the screen may be substantially higher than design, thereby reducing the potential to reduce 

impingement. In fact, if dual-flow screens are placed in relatively narrow intake bays, the approach velocity to 

the screen will likely increase and the impingement rate could increase. In general, space constraints may limit 

effective application of this technology. 

Potential for Other Adverse Effects:
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An intake structure that is reconstructed to accommodate a larger dual-flow screen may interfere with 

navigation. 

Overall Assessment of Alternative: 

Installation of dual-flow screens could result in a reduction of impingement mortality. However, in order to 

reduce through-screen velocity to 0.5 fps, installation of dual-screens would require significant expansion of 

the existing intake structure. The potential cost of this expansion and installation would need to be compared 

to the benefit to be gained from the improvement based on the results of the on-going IM study. This 

technology is recommended for further study. 

• 1b – Ristroph Screens 

Description:

This alternative would involve modification of the traveling screens so that fish which are impinged on the 

screens could be removed and returned to the source water body with minimal stress and mortality. 

A range of measures could be pursued to optimize fish handling and return. This might include more frequent 

rotation of the screens, re-fitting the screen with fish buckets, institution of low-pressure wash, replacement of 

the fish return trough, and rerouting of the fish return to a more suitable location. A complete refurbishment 

might consist of the following measures: A low-pressure spray would be used for fish removal prior to the 

high- pressure debris removal spray wash. Fish would be carried in fish buckets (i.e., water-filled lifting buckets 

designed such that they will hold approximately 2 inches of water once they have cleared the surface of the 

water during the normal rotation of the traveling screens). The fish bucket would be designed to hold the fish in 

water until the screen reaches the point where the fish are washed by the low pressure spray onto a 

sluiceway. The modified traveling screens would be operated continuously during periods when fish are being 

impinged. Removed fish would be returned to the source water body by a sluiceway with a smooth surface 

and sides that retain water such that organisms are gently returned to a location removed at least 100 feet 

from the intake structure such that the potential for re-impingement would be minimized. All surfaces of the fish 

handling and return system would be smooth to minimize abrasion damage to organisms. 

Technical Feasibility and Reliability:

The technology proposed for this alternative is well known and has been implemented for numerous power 

plants. However, a separate collection and piping system may need to be constructed to provide a separate 

return path for fish to the river or lake. This piping system would have to be constructed within the existing 

power plant footprint which could present engineering, construction, and logistics problems. Routine 

maintenance, primarily consisting of inspection and cleaning of the fish handing and return system, would be 

required but not expected to be extensive. Maintaining the system during icing conditions is likely to be 

complicated. The modified fish troughs extend farther out from the screens than conventional troughs. 

Therefore, space limitations may affect the cost and feasibility of installation. 

Cost Considerations:

The retrofit of a fish removal and return system should consider complete replacement of the existing traveling 

screens. Installation of an effective fish return system can be complex and expensive. Operation and 

maintenance activities include frequent, if not continuous, screen operation and power costs for screen and 

water spray operation. 
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Effectiveness:

Modified screens and fish handling and return systems have been used to minimize impingement mortality at a 

wide number of facilities throughout the United States (U.S.). Studies have demonstrated survival of impinged 

fish over a wide range. Survival rates of 70 to 80 percent are typically achieved for some species. It is notable 

that many small schooling species (e.g., anchovies) suffer from high mortality at traveling screens even those 

with Ristroph-type modifications. 

Potential for Other Adverse Effects:

No adverse effects are expected from this alternative. 

Overall Assessment of Alternative:

Modification to traveling screens would likely result in a reduction of impingement mortality. However, 

installation of Ristroph Screens would require significant expansion of the existing intake structure at 

considerable cost. Because this modification has the potential to reduce IM, it merits further study during the 

CDS process. 

• 1c – Fine Mesh Traveling Screens 

Description:

Typical vertical traveling screens, with mesh sizes ranging from 1/8-inch to 3⁄4-inch, are not designed to screen 

ichthyoplankton or eggs from the intake water. This alternative would involve replacement of the existing 

traveling screens with fine mesh screens having mesh spacing as small as one millimeter. This mesh spacing 

would result in a reduction of entrainment of fish eggs and larvae. In addition, an intake approach velocity of 

0.5 ft/s or less would be necessary to minimize physical damage to plankton that would be impinged on the 

fine mesh screens. 

Because of flow area for a screen with one-mm (about 1/32-inch) mesh is approximately two thirds that of a 

3/8-inch mesh, the screen area would have to be increased by nearly 50 percent to maintain the same 

through-screen velocity. For most stations, the screen area would have to be further increased to maintain a 

0.5 ft/s velocity to reduce mortality of impinged fish or shellfish. In most cases, the area around the existing 

pump house/screen house structure is not sufficient to allow for the increased number of fine mesh screens 

without substantial modification to the facilities. The screens would be operated continuously to prevent 

excessive accumulation of debris and organisms. 

The fine mesh screen structure would include curtain walls to protect against floating debris, bar racks to 

prevent submerged debris from damaging the fine mesh screens, and a screen wash and marine biota 

removal and open sluice biota return system (similar to that described for the Ristroph screen). 

Technical Feasibility/Reliability:

The technology and construction techniques required for this option have been used at a limited number of 

power plants, often with limited reliability. At two power stations, Millstone and Brayton Point, the fine mesh 

screens were replaced with standard screen mesh after clogging incidents. Based on the available 

information, it is concluded that there is a relatively high potential for fouling of the intake screens and that 

extensive maintenance would likely be required. 

In conclusion, because of the potentially large increase in screen area required, site-specific conditions may 

preclude the installation of a modified intake structure of sufficient size. 
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Cost Considerations:

The capital cost of the fine mesh screen alternative should include any necessary modifications to the intake 

structure, as well as construction of an effective fish return system to handle the more sensitive species or life 

stages of fish and shellfish. Operation and maintenance costs include one maintenance episode (6 days) each 

year, replacement parts, system monitoring by station staff (10 hours per week), and power costs. 

Effectiveness:

Fine mesh screens, with a low pressure wash and return system, have not been demonstrated to result in 

consistent effectiveness in reducing mortality at early life stages. This is a significant concern because 

organisms that are entrained and discharged may have a far greater chance of survival than if such organisms 

are impinged and subsequently washed back to the receiving water. Therefore, even though entrainment 

reductions of 50 percent to over 90 percent have been achieved at number of power stations using fine mesh 

screens, compliance with the impingement mortality performance standard could be in jeopardy. Because the 

calculation baseline levels of entrained organisms are typically far greater than the levels of impinged 

organisms, the reduction in impingement mortality will likely need to be nearly 100 percent for the early life 

stages to meet the 80 to 95 percent performance standard. 

Potential for Other Adverse Effects:

The major potential adverse effect associated with the technology is the potential unreliability of the cooling 

water flow associated with clogging events. 

Overall Assessment of Alternative:

Fine mesh screens can meet performance requirements for entrainment, but impose a relatively high potential 

for operational issues associated with screen clogging. Mortality of ichthyoplankton removed from the screens 

is likely to be high. The cost of the screen panels, as well as the cost of a revamped intake structure to 

accommodate the additional screen area required, is extremely high. Space limitations may preclude the 

installation of adequate screen area. This technology is designed primarily for entrainment reduction and is far 

too costly a remedy for IM reduction, therefore it is not recommended for further study. 

• 1d – Angled and Modular Inclined Screens 

Description:

Angled and inclined screens use standard flow-through traveling screens set at an angle to the incoming flow. 

With these screens, the angle causes the fish to move toward the end of the screen, where a bypass facility 

returns the fish to the water body. 

Technical Feasibility/Reliability 

Angled screens have been used at Brayton Point. The installation requires considerably more space than 

conventional screens. Retrofit applications would likely require substantial modifications to the existing intake 

structure. The fish handling and return system requires independently induced flow, adding to the complexity 

of the system. 

Cost Considerations:

Retrofit of angled or inclined screens should include the need to revamp the intake structure, as well as the 

installation of an effective fish return system. 
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Effectiveness:

Brayton Point has had mixed results with both diversion and latent survival, depending on fish species. EPA 

reports survival efficiency ranging from 0.1 percent for bay anchovy to 97 percent for tautog. The difference in 

effectiveness between angled screens and conventional screens with fish return is not evident. 

Potential for Other Adverse Effects: 

The bypass flow can be substantial, resulting in additional operating costs. 

Overall Assessment of Alternative:

Angled or inclined screens are in limited use. Although they may be effective in reducing impingement 

mortality, it is not clear whether their performance differs from a conventional screen. Because there is no 

apparent advantage, angled or inclined screens are not considered further in this analysis. 

Technology Alternative 2 – Fixed Screening Devices

• 2a – Wedgewire Screens 

Description:

Wedgewire screen is constructed of wire of triangular cross section such that the surface of the screen is 

smooth while the screen openings widen inwards. Fine mesh screens have slot spacing of less than 9.5 mm 

(3/8 inch) and are typically less than 3 mm. Slot size for coarse mesh screens is 9.5 mm or greater. The 

cylindrical screen design has been used at several power station applications. However, most of these 

applications have been for closed-cycle cooling systems. 

A typical installation would include an array of tee shaped cylindrical screens. If one-mm slot size were 

required, a station with a 500 MGD cooling water flow would require approximately 15 7-foot diameter by 23-

foot long screens. The screens would be placed in the intake water body at a depth such that it would not 

present a hazard to navigation. 

The screens would be cleaned periodically with an automatic compressed air system when located near 

shore. A large plenum structure would be added to the front of the intake structure to distribute the flow from 

the intake array. The existing intake structure would remain intact and functional. It could be used as a backup 

to the wedgewire screen system. The plenum structure would have openings that would allow flow to pass in 

case of screen clogging. Alternatively, wedgewire screen must be sized to minimize clogging and is subject to 

periodic manual cleaning. 

For far-offshore applications, a compressed air cleaning system is not practical. Under such conditions, the 

reliability of fine mesh screens is uncertain, and only coarse mesh wedgewire screens should be considered. 

Technical Feasibility/Reliability:

Wedgewire screens have been widely used for hydropower diversion structures. The cylindrical screen 

structures have been used successfully for many years for water withdrawals up to 100,000 gpm. Withdrawals 

of larger quantities are rare. The wedgewire cylindrical screens have been implemented at only two relatively 

large power plants with once-through cooling systems: Campbell Unit 3 on Lake Michigan, and Eddystone Unit 

1 on the Delaware River. The high number of wedgewire screens required for many plants is higher than has 
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been previously used and likely poses impractical logistical issues associated with placement in the bay or 

river. 

The long-term reliability of the wedgewire screens of the one-millimeter size is unknown. Although some 

vendors have proposed construction materials which would prevent mussel or other biological growth on the 

screens, the requirements for biofouling control are uncertain and could be substantial. The automatic 

backflushing would reduce screen fouling from both biological growth and suspended particulate matter. 

However, to be effective for screen cleaning, this system requires an ambient current to transport the removed 

particles from the vicinity of the screens. In waters with minimal current, debris accumulation may be excessive 

and backwashing ineffective. Small or negligible currents in the intake water body could make wedgewire 

screens impractical, especially fine-mesh screens. 

In addition, if the screens were to be located at a distance from the shore, considerable length of large 

diameter piping would be necessary to connect the screens to the existing cooling water system. Installation of 

such a system will result in significant cost as well as potential disruption of the site and the water body. 

Cost:

The cost for the wedgewire screen alternative should consider the distance offshore, needed piping, and airburst cleaning system. Operation and maintenance costs include two maintenance dives (6 days each) each 

year, replacement parts, and system monitoring by facility staff (10 hours per week). 

Effectiveness:

Wedgewire screens have been demonstrated to essentially eliminate impingement and, for smaller slot sizes, 

reduce larval entrainment. The 1-mm slot size has been demonstrated to reduce entrainment by over 80 

percent at some facilities. However, achievement of such results is dependent on the presence of relatively 

high ambient currents that can sweep the plankton along and past the screens. For application at the Stanton 

Station where entrainment is not a compliance consideration, a wide slot size could be utilized to help reduce 

through-screen velocity to below 0.5 fps and thereby qualifying for 316(b) compliance option #1. 

Potential for Other Adverse Effects:

The primary adverse effect associated with this alternative is the potential for obstruction to navigation caused 

by multiple submerged structures in the water body near the plant. In addition, the presence of rock rip-rap 

around a large number of screen structures can result in a “reef effect,” causing the fish population density to 

increase in the vicinity of the screen structure. This phenomenon is more likely in cases where there is very 

little spawning habitat near the intake location. 

Overall Assessment of Alternative:

The Missouri River may not provide sufficient depth near the Stanton CWIS to allow installation of wedgewire 

screens. Installation of any in-river technologies would pose a significant hazard to navigation. Additionally, 

extreme cold conditions during winter could cause excessive ice formation on the screens reducing their ability 

to provide cooling water to the station. The cost of this alternative is high and is strongly dependent on the 

number of screens needed and the length of new pipeline construction needed to interconnect all of the 

screens and to build a common tunnel to the shoreline. However, due to the existing low intake velocity and 

the potential to reduce intake velocity slightly further through installation of wide slot screens, installation of 

wedgewire screens is recommended for further study through the CDS. 
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• 2b – Perforated Pipes 

Description:

With perforated pipes, water is drawn through perforations or slots in a pipe located in the water body. EPA 

included this technology in its discussion of intake technologies. However, perforated pipes have been used 

only in small water withdrawal applications. It also is subject to clogging and fouling. It also is similar in 

principal to wedgewire screens. Therefore, this technology alternative will not be discussed further. 

• 2c – Barrier Nets 

Barrier nets are wide-mesh nets that are placed in front of the intake structure entrance. The nets are sized to 

prevent the fish from passing through, and low velocities are maintained at the net to allow affected fish to 

swim away. Barrier nets would be mounted on a frame that would allow ease of cleaning or replacement. 

Technical Feasibility and Reliability:

Barrier net systems involve technologies that are in widespread use especially in freshwater systems. 

Construction techniques that would be used for these systems are commonplace. Maintenance requirements 

include routine cleaning of debris and/or net replacement. Deployment is often limited to certain seasons 

because of the potential for winter damage from icing and storms. Finally, placement of a barrier net at the 

intake has the potential to adversely affect boat traffic. Placement typically involves suspension from existing 

pylons or walls. Creation of a new set of anchors, etc. will complicate installation and increase costs. 

Cost Considerations:

For typical power plants, the estimated capital cost for installation of barrier nets is $0.5M to $1.5M. The 

estimated operation and maintenance cost is approximately $50,000 per year for freshwater deployments. 

Operation and maintenance costs include monthly change out and annual deployment and removal. 

Effectiveness:

Barrier nets have been shown to be effective for impingement reduction at a number of facilities. Greater than 

90 percent reduction in impingement has been realized at a number of facilities. However, they are not 

effective in deterring fish eggs and larvae, or other planktonic organisms. There is the potential for clogging 

with debris; hence a routine cleaning operation is essential. Adequate area to allow low through net velocity 

(<0.5 ft/s, often <0.1 fps) is important to prevent clogging and collapse. 

Potential for Other Adverse Effects:

This alternative could pose limitations on navigation in the vicinity of the intake. 

Overall Assessment of Alternative:

There have been a number of positive experiences with barrier nets for reduction in impingement, and the cost 

is very low compared to other technologies. However, considering the long, cold winter season in North 

Dakota, nets could only be deployed during warm months and removed each winter. The effectiveness of 

placing nets during warm months would need to be investigated against the results of the on-going IM 

monitoring study to determine the effectiveness of this technology at Stanton. This alternative is 

recommended for further study. 
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• 2d – Aquatic Filter Barrier System 

Description:

Aquatic filter barrier systems are designed to completely enclose an existing intake structure and essentially 

filter the water drawn through the fabric to the intake structure. The best known manufacturer of aquatic filter 

fabric systems for power plant intake applications is Gunderboom. The Gunderboom system is a double panel, 

full water depth fabric curtain suspended from flotation billets at the water surface and secured in place by an 

anchoring system. The system includes mooring lines, ballast chain, anchoring system and an automated 

compressed air cleaning system. Automatic alarms and monitors may be installed in an appropriate control 

room to monitor the fabric alignment and system operation. 

The standard design hydraulic loading rate of the Gunderboom fabric is 3 to 5 gpm per square foot with a 

generally recommended maximum range of 10 to 12 gpm per square foot. At the recommended design 

hydraulic loading and an assumed water depth of 15 feet, a length of fabric of more than one mile would be 

required for a 500 MGD cooling water flow. Therefore at a minimum, this alternative would require that a large 

area around the intake structure be encompassed by the fabric for most large power stations with oncethrough cooling. 

Technical Feasibility/Reliability:

The technology and construction techniques required for this option have been fully implemented only at the 

Lovett Power Plant in New York State. Clogging of the Gunderboom is a routine maintenance issue. The 

length of fabric required would encompass a large area around an intake structure. Aquatic filter barriers are 

not likely to withstand the icing conditions encountered in the Great Plains region. A Gunderboom would 

require seasonal deployment, increasing the operation and maintenance costs. 

Cost Considerations:

The estimated capital cost of the Gunderboom alternative is high compared to other near-shore technologies. 

The operation and maintenance costs include the mobilization and installation/demobilization and removal of 

the system each year. They also include regular underwater inspections of the filter curtain each month and 

one thorough underwater inspection each year. 

Effectiveness:

Aquatic filter barriers have been demonstrated to be effective in substantially reducing larvae entrainment and 

fish impingement losses at power station intakes on the Hudson River. As a result, the New York State DEC is 

a strong advocate of this technology for entrainment and impingement reduction. However, clogging and 

ambient conditions can increase the risk of fabric failure, rendering the system ineffective. 

Potential for Other Adverse Effects: 

Because this aquatic filter barrier application would require closing off much of the waterbody near the plant, 

navigation would be restricted. The potential for aquatic organisms to be impinged in the fabric is a concern. 

Overall Assessment of Alternative:

Based on the logistical and potential navigation issues associated with the extensive area of the waterbody 

that would be encompassed by the aquatic filter fabric, operational issues associated with potential clogging of 

the fabric, potential damage from floating debris, and the costs associated with biannual installation and 

removal, it is not likely that this alternative would be practical in any once-through application with large flow 

rates, particularly at Stanton. Installation of aquatic filter barriers is not recommended for further study. 
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• 2e – Porous Dams/Leaky Dikes 

Description:

Porous dams, also known as leaky dams or leaky dikes, are filters constructed of stones surrounding the 

cooling water intake. The core of the dike is composed of gravel or stone which allows water to be drawn 

through it. The exterior of the dike is armored with larger rocks. The dam serves as a behavioral and physical 

barrier to aquatic organisms. The reduced flow rate across the full face of the dam greatly reduces 

impingement, however, “hot spots” of high velocity may be present in local areas of high porosity, and its 

effectiveness in screening fish eggs and larvae is not well established. 

Technical Feasibility and Reliability:

Because of its size, a porous dam constructed around an intake structure may not be practical in waterbodies 

of limited size, because of potential impacts to navigation. 

Cost Considerations:

Because of its large size, a large part of the capital cost of a porous dam is materials (stone and gravel). 

Operation and maintenance would include routine maintenance and potentially heavy cleaning or dredging 

every 5 years. 

Effectiveness:

If the surface area is sufficiently large, the porous dam intake structure could result in a lower impingement 

rate, but may not decrease the entrainment rate. The porous dam would decrease impingement due to low 

intake velocity across the dam face and the physical barrier created by the stones used in the dam. The dam 

structure would need to be located such that its construction does not impact known spawning beds. The 

presence of the stone could create spawning areas where there were none and could actually serve to 

increase entrainment. Alternatively, potential spawning areas created by the porous dam may act as a 

restoration measure and increase the production of fish in the water body. 

Potential for Other Adverse Effects:

Significant biofouling could be expected due to algae and aquatic weeds (e.g., watermilfoil). Biofouling of the 

porous dam would reduce plant cooling water intake rate. Frazil ice formation should be expected in the winter 

months and the dam itself would be subject to structural damage from surface ice. The size of the porous dam 

is large, and its construction has the potential to damage fish spawning areas. In smaller waterbodies, a dam 

of sufficient size to effectively reduce intake velocity could impede shipping and boating. 

Overall Assessment of Alternative:

A porous dam will likely be effective for reduction in impingement if designed for low intake velocity. However, 

to achieve low intake velocity, the dam would have to be built well out into the river navigation channel making 

it impractical for this location. Installation of a porous dam is not recommended for further study. 
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Technology Alternative 3 – Submerged Offshore Intake Structure 

Description:

An offshore intake structure alternative would consist of a structure with velocity cap (or other technology such 

as wooden cribs or wedgewire screens), and a single pipeline into the station. The size of the structures would 

be designed to achieve a nominal intake velocity of 0.5 ft/s. The velocity cap on the structure provides 

horizontal flow that reduces the potential for fish impingement. The intake structures would be located in the 

water body at a water depth of at least 20 feet. The intake pipeline would be placed by either trenching or 

tunneling. 

Technical Feasibility/Reliability:

The technology and construction techniques required for installation of submerged intake structures are well 

known and understood. Submerged intakes have been constructed at several facilities and have been shown 

to be reliable in the long term. Considerations for designing and constructing the alternative include 1) 

technology associated with sub-surface placement of the pipe and potential impacts to the bottom along 

pipeline route, 2) the length of pipeline needed to reach sufficient depth, 3) prevention of fouling on the 

structure, 4) the potential for adverse impacts due to debris, and 5) the need to avoid obstruction of navigable 

waters. 

Another technical consideration for the offshore intake structure alternative is that the intake water could have 

a reduced temperature which would potentially improve power plant performance. 

Cost Considerations:

The estimated capital cost of submerged offshore intake is highly dependent on the length of new pipeline 

needed. One 6-day dive per year would be required for maintenance. 

Effectiveness:

The offshore intake structures could result in a lower impingement rate if designed with low intake velocity and 

velocity cap. Suitable placement of the intake off-shore may reduce the density of eggs and larvae subject to 

entrainment relative to an on-shore location. The intake structure construction could impact spawning beds. 

The presence of the intake structure and associated anchor stone and rip-rap could create new spawning 

areas that did not previously exist and could actually act to increase entrainment. 

Overall Assessment of Alternative:

The Missouri River does not provide sufficient depth near the Stanton CWIS to allow installation of offshore 

intake structures. Installation of any in-river technologies would pose a significant hazard to navigation. 

Installation of any offshore intake structure is not recommended for further study. 

Technology Alternative 4 – Fish Diversion and Avoidance

• 4a – Louvers and Angled Bar Racks 

Description:

Diversion devices are physical structures intended to guide fish away from and out of the intake flow. 

Examples of such devices include angled bar racks and louvers, which are made of a series of evenly spaced, 
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vertical slats placed across a channel at an angle leading to a bypass area. The louvers create localized 

turbulence that the fish detect and avoid. The louver systems have been tested at hydroelectric facilities on 

rivers. 

Typically, angled bar racks and louvers would be in semicircular fashion around a shoreline intake or placed 

across the mouth of an intake canal. Louvers would be constructed of material compatible with the 

environment (for example, polyethylene slats for louvers and nylon for nets), and would be mounted on a 

stainless steel frame, approximately 12 inches apart. 

Technical Feasibility/Reliability: 

Louver systems involve technologies that are in widespread use. Construction techniques that would be used 

for these systems are commonplace. Maintenance requirements could be potentially extensive. Divers will 

likely be required to routinely clean and/or replace the bar racks or louvers. The potential for damage and 

clogging from ice and debris is real. Finally, placement of a louver at the intake has the potential to adversely 

affect boat traffic. 

Cost Considerations:

The capital cost for installation of louvers should include consideration for debris loading and damage. 

Operation and maintenance costs include two 6-day dives per year to clean and maintain the louvers. 

Potential Effectiveness:

These diversion devices are not effective in deterring fish eggs and larvae, or other planktonic organisms. 

Louvers have been tested only in rivers with a substantial current velocity along the bank. They are most 

effective in diverting migratory fish from intakes in confined river channels, and therefore would be less 

effective in lakeside applications. 

Potential for Other Adverse Effects:

This alternative could pose limitations on navigation in the vicinity of the intake. 

Overall Assessment of Alternative:

Louvers/bar racks can effectively reduce impingement of some species of fish, but would not be effective for 

reducing entrainment. This alternative has relatively high probability of clogging associated with ice, debris, 

and biological growth. Because this technology is a permanent installation which could not be removed each 

winter, it would be subject to damage from floating ice and subject to clogging from ice formation. This 

technology is not recommended for further study. 

• 4b – Velocity Caps (installed on existing offshore intake) 

Description:

A velocity cap is a cover placed on a vertical inlet of an offshore intake structure. The cover results in a 

horizontal flow to the intake, and may reduce impingement because fish tend to avoid rapid changes in 

horizontal flow. Intake velocities of 0.5 to 1.5 ft/s are common. 
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Technical Feasibility/Reliability:

Installation of a velocity cap on an existing offshore intake may be limited because of water depth and potential 

interference with navigation. For some applications, a velocity cap may require routine inspection and 

maintenance to remove accumulated debris. 

Cost Considerations:

Costs of installation of a velocity cap on an existing offshore intake should consider intake modifications and 

materials of construction. 

Potential Effectiveness:

Although velocity caps in new offshore intakes have been shown to result in reduced impingement, it is 

uncertain whether the reported reductions are due to the velocity caps or the new offshore locations. Velocity 

caps should be designed to minimize intake velocity through the intake structure openings; a maximum intake 

velocity of 0.5 feet per second should be considered to meet the Phase II intake velocity threshold. In some 

cases, additional measures (e.g., intake screen improvements, deterrent systems) may be needed to meet 

impingement performance goals. Velocity caps have no impact on entrainment, although the off-shore location 

may result in lower entrainment levels compared to an on-shore calculation baseline intake configuration. 

Potential for Other Adverse Effects:

The addition of a velocity cap to an existing intake may interfere with navigation. 

Overall Assessment of Alternative:

Velocity caps are only practical for installation at existing in-river intake structures or as part of a new in-river 

intake structure. As with other in-river technologies, the hazard to navigation and potential for damage from 

floating ice make this an impractical technology for Stanton. Velocity caps are not recommended for further 

study. 

• 4c – Strobe Lights, Acoustic Deterrent, Bubbles, Chains 

General Description: 

Behavioral barriers are intended to cause fish to actively avoid entry into the intake flow. Examples include 

sound barriers, light barriers, air bubble curtains, chains and cables, and electrical barriers. They are often 

implemented in combination with other devices such as physical barriers (e.g., fish nets). The potential 

behavioral barriers are briefly described below. 

Sound barriers consist of devices located at the intake structure, which create sound that repels the fish. 

Three types of underwater sound have been tested for this application: low-frequency infra-wave sound, lowfrequency sound generated by pneumatic/mechanical devices, and transducer-generated sound covering a 

wide range of frequencies. Low frequency, high-intensity devices have been shown to be effective. High 

frequency (125 kHz) devices have been reported to be effective in the Great Lakes. Pneumatic impact 

devices, “poppers”, and “hammers” are examples of devices that have been effective in reducing impingement 

of some fish such as alewife at power plant intakes. There is some concern that pressure waves from 

pneumatic devices may be harmful to nearby organisms. In most cases, the use of high-intensity, multifrequency sound has not been effective in repelling a wide range of fish species from intakes due to the 

diversity of species and sizes of species in the receiving water. 
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Light barriers consist of a series of underwater lamps that emit a constant or intermittent (strobe) beam of 

light. The effectiveness of light barriers as a deterrent has been variable, and even contradictory, in many 

studies. In some studies fish have been attracted to light while in others they have been repelled. Constant 

light has been more effective than strobe light in guiding young salmon whereas strobe light has been effective 

in repelling alewife and gizzard shad. Filtered mercury vapor light has been found to attract certain species of 

fish away from strobe lights in field studies in Europe. At the Nanticoke Generating Station on Lake Ontario, 

smelt, shad, white bass and shiner have been successfully guided away from intake trash racks using mercury 

vapor light. However, evidence of consistently reliable effectiveness for a wide range of fish species does not 

exist. 

Air bubble curtains or screens consist of a series of diffuser pipes mounted on the base of the intake 

structure. The diffusers create a continuous, dense curtain of bubbles, which can repel fish. Generally, the air 

bubble screens have not been successful. They are not effective at night and in turbid water. In one case, at 

Indian Point Generating Station on the Hudson River, the air bubble screen actually attracted fish at night. 

Chains or cables can be hung vertically from the top of the intake structure to form a physical, visible barrier 

to fish. The results of studies of this behavioral barrier have been contradictory. The effectiveness of chain 

barriers is dependent on flow velocity, turbidity and illumination. Debris buildup on hanging chains can disrupt 

hydraulic flow patterns at the intake. 

Electrical barriers consist of a series of electrodes at either side of the intake structure. These barriers have 

had limited success and can present a safety threat. 

Technical Feasibility/Reliability:

All of the behavioral barrier systems are technically feasible and reliable from the perspective of construction, 

operation, and maintenance. The behavioral barrier systems that have been implemented with the greatest 

frequency are sound and light barrier type systems. Each of these potential alternatives would consist of a 

metal support structure constructed at the front of the intake, sound or light emitting devices mounted on the 

supports, a power supply, controllers, power cables and mounting hardware. The construction and technology 

used for these alternatives have been regularly applied. To ensure long-term reliability of these systems, 

ongoing maintenance will be required. Maintenance of the systems would include cleaning and replacement of 

light bulbs (for light barrier systems) and prevention of corrosion of the supporting structure. 

Cost: 

The estimated capital cost of behavioral barriers (e.g., a strobe light barrier system) is generally lower than 

other technologies. Operation and maintenance costs include items such as the replacement of strobe lights 

each year using divers, and 10 hours per week of on-site monitoring by station staff. Costs for other behavioral 

barrier systems would be similar. 

Effectiveness:

Because these barriers rely on the ability of the organism to respond to a stimulus, they are not effective in 

protecting fish eggs and larvae, or other planktonic organisms. In addition, the effectiveness of these barriers 

varies among species and across age groups within species. These barriers are most effective when a single 

species of fish of the same size and age is to be protected. Many the behavioral barriers have not been fieldtested so their effectiveness has been extrapolated from laboratory studies. None of these devices has been 

demonstrated to be consistently reliable in obtaining an avoidance response from a wide range of fish species. 

Therefore, installation of behavioral barriers would not result in reduction of entrainment, and a reduction in 

impingement is possible but uncertain. 
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Potential for Other Adverse Effects:

A potential adverse effect of the behavioral barrier alternative is a slight potential for increased attraction of fish 

to the intake structure. Also, any structure installed near the intake has the potential to disrupt navigation. 

Overall Assessment of Alternative:

Behavioral barriers may effectively divert specific fish species and therefore could be a component of an 

overall impingement mortality reduction. Based on site- and species-specific variation in response, pilot testing 

is likely to be necessary. One or more of the behavioral barrier systems may merit further study after 

completion of the on-going IM study. 

Technology Alternative 5 - Flow Reduction

• 5a – Variable Speed Pumps 

Description:

Variable speed cooling water intake pumps are potentially useful for reducing cooling water flow and the 

associated entrainment and impingement during peak periods of biological activity. The decrease in cooling 

water flow results in an increase in plant condenser delta T (temperature increase through the condenser) and 

discharge temperature. Therefore, variable speed pumps are most appropriate during cold water periods of 

the year (winter and spring) in temperate climates where an increase in discharge temperature will not cause a 

significant increase in biological effects or cause discharge temperatures in excess of maximum acceptable 

levels. 

For other facilities, this alternative was considered with the assumption that variable speed pumps would be 

installed to decrease the cooling water flow by 25 percent during periods of potentially high entrainment and 

impingement. This alternative would require replacement of existing single speed drives with adjustable speed 

drives (ASD) on the circulating water pumps. An on-line condenser tube cleaning system is included in this 

alternative to alleviate tube fouling which could potentially occur because of lower water flow rates. 

Technical Feasibility and Reliability:

The replacement of the existing single speed drives with ASDs is a technically feasible and reliable alternative. 

However, under full power production conditions using the existing condensers for the units, this alternative, 

specifically a 25 percent reduction in flow, could reduce the reliability and efficiency of the entire system. 

Specifically, the reduction in flow through the condensers could cause operational difficulties (i.e., condenser 

tube fouling), cause decreased thermal efficiency in the turbines, limit or reduce maximum power production, 

require condenser replacement, and alter the thermal plume effects at the discharge. 

Cost:

The estimated capital cost of the variable speed pump alternative is $0.5M per cooling water pump. This 

capital cost assumes that replacement of the existing condensers would not be required. Operation and 

maintenance costs are difficult to estimate without input from the individual stations regarding thermal 

efficiency as well as market rates. It should be noted that costs associated with losses of thermal efficiency are 

likely to be partially offset by the gain in not operating the pumps at full capacity. This cost assumes that the 

plant could be operated at full capacity during reduced cooling water flow. 
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Effectiveness:

The use of variable speed pumps to decrease the flow of cooling water through the intake would effectively 

reduce the entrainment and impingement in the system; however, the resulting increase in temperature in the 

discharge could increase thermal plume effects. The alternative would amount to a relatively small reduction in 

flow – and corresponding reduction in impingement and entrainment effects – of approximately 25 percent for 

the entire plant during periods of time when the ASDs are in operation. Since the ASDs would not be used 

during the entire year, the overall reduction in impingement and entrainment would be substantially less than 

25 percent. 

Potential for Other Adverse Effects:

As noted above, reduction in cooling water flow during normal station output would result in an increased 

discharge ΔT value which could, in turn, cause altered thermal plume effects. 

Overall Assessment of Alternative:

By itself, this alternative will not likely achieve performance goals for impingement reduction, though it may be 

considered as one component of an overall compliance plan. However, any reduction in intake volume would 

likely result in an increase in discharge temperature and risk exceeding temperature limits set in the NPDES 

permit under Section 316(a). This alternative is recommended for further review during preparation of the 

CDS. 

• 5b – Capacity Factor Reduction 

Description:

A power plant can reduce impingement and entrainment by reducing cooling water requirements through 

reduced capacity factor of the facility. This approach would require a commitment on the part of the facility to 

limit cooling water flow to a level below the design flow rate. Unless a very low capacity factor is intended, this 

approach will likely be used in conjunction with other technologies to meet performance goals. 

There is the potential that regulatory agencies will limit the applicability of this approach for facilities with 

historically low capacity factor. Although the calculation baseline is based on design capacity, the commitment 

to set a capacity factor limit by a facility with historically low capacity factor may be viewed as an inappropriate 

approach to meeting the performance goals unless a restriction is included in the plant NPDES permit. 

Technical Feasibility and Reliability:

Reduced water flow rate will limit the power production rate based on thermodynamics as well as the thermal 

discharge limits for the facility. 

Cost Considerations:

Reduction on capacity of a facility will have very large financial impact on the ability of a facility to generate 

revenue. The capital cost to implement this approach could involve installation of equipment to limit operations; 

however, record keeping may be all that would be required to demonstrate the flow reduction achieved. 

Effectiveness:

A capacity factor reduction and resulting reduced flow rate should at least reduce impingement and 

entrainment in proportion to flow reduction. Seasonal differences in density of aquatic life would need to be 
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Document No.: 10735-002-400

considered to determine the overall annual reductions in impingement and entrainment from the calculation 

baseline. 

Potential for Other Adverse Effects:

This approach reduces power generation capacity, which would have to be made up elsewhere. 

Overall Assessment of Alternative:

If acceptable to the regulating agencies, this alternative may be a component of compliance. This alternative 

is recommended for further study during development of the CDS. 

• 5c – Evaporative Cooling Towers 

Description: 

The existing cooling water system uses river water pumped through a steam condenser and discharged back 

to the source water body. This type of system is generally referred to as an open cycle or once-through cooling 

system because the water simply passes through the condenser (no recirculation) where heat is transferred 

from the steam to the cooling water prior to discharge. Closed cycle systems recirculate the cooling water in a 

closed piping system. The heated water from the condenser is cooled down in each cycle using evaporative 

cooling. This cooled water is then recirculated to the condenser to cool and condense the steam from the 

turbine. In the mechanical draft-cooling tower, fans are used to circulate air that flows against the heated water 

sprayed inside the tower. Cooled water is collected in the tower basin and returned to the condenser. Water 

must be introduced into the system at regular intervals to make up for losses due to blowdown and 

evaporation. The closed cycle evaporative cooling systems require a water withdrawal rate that is about 3 to 

5 percent of the amount of water required in once-through cooling systems. 

The makeup water flow for a mechanical draft-cooling tower is typically less than 5 percent of the flow required 

for once-through cooling. The makeup flow would be pumped to the circulating water system from the current 

intake structure. 

Technical Feasibility and Reliability:

The technology proposed for this alternative is well known and has been implemented for similar power plants. 

However, this alternative requires substantial open space, consumes a substantial amount of electricity, and 

reduces the thermal efficiency of the system. In addition, the ability of the existing condensers to handle the 

higher pressures associated with the recirculating system is uncertain and could have a large effect on the 

costs for this alternative. 

Costs:

The capital cost of the mechanical cooling tower alternative is very high. Operation and maintenance costs are 

typically estimated to be in the millions of dollars per year, primarily due to additional fan and pump power 

demands and water treatment requirements. Finally, the increased temperature of cooling water in the steam 

condensers will results in both efficiency and capacity losses for the generating units. During the hottest 

summertime conditions when electricity demand is highest, the efficiency and capacity losses could be as high 

as 10 percent. This will result in the need to purchase replacement power at a premium because a public utility 

has an obligation to serve its customers and will be required to bear that expense. 
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Effectiveness:

The mechanical draft cooling tower alternative would effectively reduce both impingement and entrainment in 

proportion to the flow reduction, typically 95 percent or more. This technology meets both the impingement 

mortality reduction and entrainment reduction performance standards set by the 316(b) Phase II rule for 

existing facilities. 

Other Potential Adverse Effects: 

The primary adverse effects for the mechanical draft cooling tower alternative are associated with increased 

water vapor content in the immediate area of the cooling towers. This will result in a visible plume for some 

periods and has the potential to result in fogging impacts. To reduce the potential for these effects, a plume 

abatement system would be employed. Because cooling tower drift cannot be eliminated completely, the tower 

would be located as far as possible from electrical equipment, off-site receptors, and sensitive vegetation. 

Space limitations may make it difficult to locate the cooling towers to minimize these effects. A cooling tower 

also imposes noise and aesthetic impacts. Another significant environmental effect is that the decrease in 

efficiency means that more fuel is burned per unit of electrical energy output. Therefore, a plant with cooling 

towers will have more emissions than a plant utilizing an open cycle system. The increase in emissions will be 

proportional to the decrease in plant efficiency. Depending on the weather conditions, the negative effect on 

efficiency could be anywhere from 1 to 10 percent. 

Overall Assessment of Alternative:

A cooling tower alternative would be effective for reduction of both entrainment and impingement mortality; 

however, due to the very high costs and limited space available for construction, this alternative is not 

considered as a part of the compliance. 

• 5d – Dry Cooling 

Description:

With a dry cooling system air is used as a heat sink to condense steam in the system. Cooling water is 

essentially eliminated. However, a dry cooling system requires a large cooling surface, many cooling fans, and 

a more sophisticated steam ducting system, which would require extensive modifications to an existing facility. 

In addition, an annual average thermal efficiency penalty of 2 to 5 percent is likely for the power plant. During 

the hottest summertime conditions when electricity demand is highest, the efficiency and capacity losses could 

be well over 10 percent. Because of these high costs, dry cooling is not considered a part of the compliance 

for any existing facility. 

Technology Alternative 6 – Restoration 

Description:

The USEPA 316(b) regulations allow the use of mitigation strategies for enhancing fish and aquatic biota 

populations to offset impingement and entrainment losses. These strategies typically involve habitat 

restoration methodologies, particularly the creation and improvement of important habitat types that support 

aquatic biota, as well as spawning and nursery areas. Alternatively, ENSR is aware of several fish-stocking 

efforts in the southern U.S. that are viewed as successful by all parties involved. Ideally, the restoration activity 

should result in mitigating the types of species that are affected by entrainment and impingement at the plant 

and result in quantifiable benefits near the station. Alternatively, the rule allows for “out-of-kind” restoration, 

which might be simpler to institute and monitor. 
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NDG&F operates a fish hatchery nearby for the purposes of providing stock to the Missouri River and 

tributaries. Various additional fish and habitat restoration strategies could be considered for the Missouri River 

in association with the NDG&F and NDDH including wetland creation or habitat creation. 

The restoration process would involve the following activities: 1) evaluation of impingement data to assess 

target species and associated habitat restoration strategies; 2) selection of the most appropriate restoration 

strategies and areas for restoration; 3) implementation of selected restoration strategies; and 4) coordination 

with relevant resource agencies (e.g., NDDH, NDG&F, USFWS) to gain approval. 

Technical Feasibility/Reliability

Each of the potential restoration methods has been used with success in a number of applications. Each of the 

restoration methods would require an assessment of whether any conditions in the river would preclude longterm success. The potential for court-remanding of the restoration measures also should be considered. 

Cost

Annual costs associated with fish stocking (assumed to continue for ten years) range from $20,000 to 

$100,000. 

Effectiveness

There is little existing quantitative information on using increases in biological production at habitat areas to 

offset impingement and entrainment losses. However, restored habitat areas have been demonstrated to 

result in an increase in biota and spawning. Alternatively, a well-designed stocking program may be able to 

provide a more direct replacement of important species on an adult-equivalency basis. It should be noted that 

restoration does not reduce the rate of impingement mortality at CWISs. 

Other Adverse Effects

There are no likely adverse effects of the restoration alternative. 

Overall Assessment of Alternative

This alternative is technically feasible, has comparatively moderate costs, and is likely to be effective (though 

at this point it is difficult to quantify the degree of mitigation that would be obtained). The alternative also would 

provide an overall environmental benefit to the Missouri River. This alternative is recommended for more 

detailed analysis. 
December 2006

Document No.: 10735-002-400

Appendix B 

EPA Cost Estimate 
Table B-1:

US EPA-Estimated Compliance Costs based on the Model Facility Approach for the Section 316(b

Source: Appendices A and B of the Final Rule in the Federal Register, July 9, 2004.

Column 1

Facility Name

Column 2

Facility ID

Column 3

Intake ID

Column 4

EPA 

Assumed 

Design Intake 

Flow, gpm 

(xepa)

mgd Column 5

Capital Cost

Column 6

Baseline 

O&M Annual 

Cost

Column 7

Post 

Construction 

O&M Annual 

Cost

Column 8

Annualized 

Capital + Net 

O&M Using 

EPA Design 

Intake Flow2 

(yepa)

Stanton AUT0273 1 173,689 250 $994,534 $52,039 $208,703 298,263 

1 The design flow adjustment slope (m) represents the slope that corresponds to the particular facility using the technology in column 3.2 Discount rate = 7%.3 Amortization period for capital costs = 10 years.4 Amortization period of downtime and pilot study costs = 30 years.

Note: Depending on the data provided, some facilities with multiple intakes were costed separately for each intake. In such cases, the facility should calcu

each intake using the steps below and sum. Note that some costs (e.g., construction downtime) are assigned evenly to each intake for convenience.

5 EPA Technology Codes:

1. Addition of fish handling and return system2. Addition of fine mesh screens to an existing traveling screen system.3. Addition of a new, larger intake with fine-mesh screens and fish handling and return system in front of existing screen.4. Addition of passive fine-mesh screen system (cylindrical wedgewire) near shoreline with mesh width of 1.75 mm.5. Addition of fish net barrier system.6. Addition of an aquatic filter barrier system.7. Relocation of existing intake to a submerged offshore location with passive fine-mesh screen inlet with mesh width of 1.75 mm

8. Addition of a velocity cap inlet to an existing offshore intake.
December 2006

Document No.: 10735-002-400

Appendix C 

Sampling Plan 
Impingement Monitoring Plan 

2005-2006 

Basin Electric, Leland Olds Station 

Great River Energy, Stanton Station 

Minnkota Power Cooperative, Inc., Milton R. Young Station 

Prepared for: 

Basin Electric 

Great River Energy 

Minnkota Power Cooperative, Inc.

Prepared by: 

ENSR 

1601 Prospect Parkway 

Fort Collins CO 80525 

Project Number 10735-002-400 

May 2005 
10735-002-400 August, 2005 i

CONTENTS 

1.0 INTRODUCTION......................................................................................................................1-1

2.0 STATION DESCRIPTIONS .....................................................................................................2-1

3.0 SOURCE WATER BODY INFORMATION.............................................................................3-1

4.0 FIELD AND LABORATORY PROCEDURES ........................................................................4-1

5.0 DATA ANALYSIS ....................................................................................................................5-1

5.1 Fish Data .......................................................................................................................5-1

5.2 Plant Operating Data.....................................................................................................5-1

5.3 Impingement Estimates ................................................................................................5-2

6.0 QUALITY ASSURANCE/QUALITY CONTROL PROCEDURES..........................................6-1

6.1 Mobilization ...................................................................................................................6-1 

6.2 Sample Collection .........................................................................................................6-2 

6.3 Recording Data .............................................................................................................6-2 

6.4 Datasheets ....................................................................................................................6-2 

6.5 Container Labeling........................................................................................................6-3 

6.6 Safety Precautions........................................................................................................6-3 

6.7 Collection of Biological Data .........................................................................................6-3 

6.8 Deviations from QA/QC Plan or SOP...........................................................................6-4 

6.9 Data Management ........................................................................................................6-5 

6.10 Sample Tracking ...........................................................................................................6-5

7.0 STUDY REPORT .....................................................................................................................7-1

APPENDIX A – BIBLIOGRAPHY 
10735-002-400 August, 2005 ii

LIST OF FIGURES 

2-1 Site Location Map...................................................................................................................2-2

3-1 Fish Species Identified in the Garrison Reach ......................................................................3-3

3-2 Summary of Fish Collected at Stanton Station 1997-2004 ...................................................3-4

4-1 Impingement Collection Basket .............................................................................................4-2

4-2 Proposed Schedule of Sampling Events ...............................................................................4-4

4-3 Impingement Study Team......................................................................................................4-5
10735-002-400 August, 2005 1-1

1.0 INTRODUCTION 

This impingement monitoring plan has been developed to facilitate the collection of aquatic 

organisms from the intakes of three operating power plants that draw water from the Missouri 

River. The three power plants are Basin Electric’s Leland Olds Station, Great River Energy’s 

Stanton Station, and Minnkota Power’s Milton R. Young Station. These stations withdraw water 

from the Missouri River for cooling purposes and are subject to compliance with the requirements 

of Phase II of Section 316(b) of the Clean Water Act. This impingement monitoring plan is one 

component of the Proposal for Information Collection (PIC) that will be submitted separately for 

each facility. 

Phase II of Section 316(b) of the Clean Water Act requires plants that withdraw 50 million gallons 

a day (MGD) or more of cooling water from surface water bodies to reduce entrainment and/or 

impingement of aquatic organisms to specific minimum levels through retrofit or restoration, or 

demonstrate that such measures are not beneficial or are prohibitively expensive. A component of 

the initial phase of this compliance demonstration is to document or determine the baseline 

entrainment/impingement rates to support the selection of a compliance strategy and ultimately 

quantify and confirm its effects. 

Implementation of the Phase II program and subsequent demonstration of compliance by 

individual plants are administered under federal and state NPDES programs. The North Dakota 

Department of Health (NDDH) has primacy for the administration of the state’s NPDES program 

and is responsible for overseeing and approving compliance activities. 

These three stations all withdraw more than 50 MGD from surface water bodies and are subject to 

Section 316(b) requirements. Leland Olds Station and Stanton Station are located on the Missouri 

River, and the Milton R. Young Station has a cooling water intake structure (CWIS) on the 

Missouri River, though the station is located 13 miles south on Nelson Lake. Since each station 

withdraws less than 5 percent of the mean annual river flow, they are not subject to requirements 

to reduce entrainment. However, they are subject to the impingement reduction requirements. 

There are no historical or current data for impingement rates at any of the station intakes. 

Because North Dakota Game and Fish conducts biannual sampling of the river in the vicinity of 

the power plants, there are reliable and recent data on fish populations in this segment of the 

Missouri River. 

Because of the lack of impingement data, Basin Electric, Great River Energy, and Minnkota 

Power have decided to support a joint impingement monitoring study whose data can be utilized 

for all three stations. This plan provides the detailed procedures for the field, laboratory, and data 
10735-002-400 August, 2005 1-2

analysis components of this year-long study. Its purpose is to ensure consistent and reliable data 

collection and analyses. 

The overall purpose of this impingement monitoring study is to collect reliable and site-specific 

data on the rate of impingement of aquatic organisms at the cooling water intakes of these three 

power plants. The data will then be analyzed to determine the potential impact of impingement 

losses to resident populations of organisms in this segment of the Missouri River. The results of 

these analyses will be utilized to select the appropriate strategy for compliance with Section 

316(b) requirements at each station. 
10735-002-400 August, 2005 2-1

2.0 STATION DESCRIPTIONS 

All three stations have relatively similar intake configurations. Their locations on the Missouri River 

are presented in Figure 2-1. The stations and intakes are briefly described below. 

Leland Olds Station (LOS)

LOS has two operating units that generate approximately 656 MW and withdraw approximately 

330 MGD during normal operation. Each unit has a CWIS that includes two short concrete 

forebay (total of four forebays) that are essentially flush with the river bank. A spray header in front 

of each of the forebays is used in the winter to reduce ice build-up and in the winter, some of the 

warm water that has passed through the plant is returned to the forebays to raise the temperature 

of the incoming water and prevent ice formation. Also, during winter operation, the warm water 

discharge is moved to a location upstream of the intake structures to help minimize ice build-up. A 

submerged spray header is used to wash sediments away from the front of the forebays, as 

necessary. 

Water is pulled into the forebays and through trash racks that exclude large objects. At each 

CWIS, water then flows through dual vertical traveling screens and to dual pumps. The 3/8-inch 

mesh traveling screens are cleaned with 125 psi wash sprays when the operator determines from 

visual evaluation that build-up is occurring. The screens are also equipped with pressure drop 

instrumentation – when the pressure drop across the screens exceeds a setpoint, the wash 

sprays are automatically operated. Wash water is sprayed through the screens and material that 

is washed off the screens flows to a sluiceway that returns the collected material directly to the 

river. 

LOS represents an intake configuration that EPA considers “baseline” (as defined at 40 CFR 

125.93), i.e., the intake is located flush and parallel with the shoreline, withdraws water from the 

surface and shallow depths of the river and has traveling screens with 3/8” mesh and no type of 

fish return system. References to a “baseline” configuration throughout this document refer to the 

situation at LOS. 

Stanton Station

Stanton Station has two operating units that generate approximately 172 MW and withdraw 

approximately 144 MGD during normal operation. Stanton Station’s intake design is very similar to 

LOS’s design except that each unit has a single concrete forebay and each of the forebays are 

somewhat longer, with a distance of approximately 40 feet from the river bank to the trash racks. 

In addition, the sluiceway from the traveling screens exits the pumphouse building and flows onto 
.

0 500 1,000 2,000

Meters

0 125 250 500

Meters

Stanton Station

Leland Olds Station

Milton R. Young Station

Missouri River CWIS

Stanton Station CWIS

L.O.S. CWIS

Young Station CWIS

0 25 50 100

Scale 1:24,000 Meters Scale 1:6,000

Scale 1:45,000

SITE LOCATION MAP

Combined 316b Compliance Project Sampling Plan

Basin Electric Minnkota Power Cooperative Inc.

Great Rivers Energy

Figure 2-1

USGS B/W 1M Aerials 09/16/1997

Oliver County, ND

Fort Clark Quadrangle

Drawn by: MG

NDG&F Sampling Point
10735-002-400 August, 2005 2-3

the ground adjacent to the building. The slope of this area allows water to flow approximately 30 

feet back to the river. The majority of debris and material is collected on the ground and is 

periodically removed manually. 

Milton R. Young Station

The Milton R. Young Station has two operating units that generate approximately 700 MW, and is 

located 13 miles south of the Missouri River on Nelson Lake. The station draws cooling water 

from Nelson Lake through two CWIS. Nelson Lake is provided make up water through a pipeline 

from a CWIS on the Missouri River, located approximately 5 miles downstream of LOS. The 

Missouri River CWIS has the capacity to withdraw 19.4 MGD with two pumps operating, but 

normally only operates one pump, which a capacity of 11.2 MGD. The Missouri River CWIS 

includes a single traveling screen that receives water through a covered forebay that is 

proportionally smaller than the LOS SWIS, and does not include warm water recirculation for 

winter operations. The screen wash return is through a sluiceway that empties directly back into 

the river. 

The sampling plan for the Nelson Lake CWIS will be addressed in a separate sampling plan 

submittal to the NDDH. 
10735-002-400 August, 2005 3-1

3.0 SOURCE WATER BODY INFORMATION 

The three power plant CWISs are located on the Garrison Reach of the Missouri River. This reach 

has been studied thoroughly with regard to aquatic species for many years by Federal and State 

agencies as well as other independent researchers. Over 17 reports on various aspects of the 

status of the fishery along the Garrison Reach have been researched during the development of 

this sampling plan (a bibliography of these sources is provided in Appendix A). Most significantly, 

North Dakota Game and Fish Department has conducted fish population studies in the Garrison 

Reach since 1991. These studies involved biannual fish collection at seven locations in the 

Garrison Reach. One of these collection locations is offshore of the Stanton Station cooling water 

outfall, which is located just downstream of the Stanton CWIS and upstream of the LOS CWIS, 

and which is in a similar river regime as the Milton R. Young Station river CWIS, 4 miles 

downstream. The location of the North Dakota Game and Fish Stanton sampling point is identified 

on Figure 2-1. 

Section 125.95(b)(3)(i)-(iii) of the Phase II Rule stipulates that the Impingement Characterization 

Study must include the following to support development of the CDS: 

(i)”Taxonomic identifications of all life stages of fish, shellfish, and any species 

protected under Federal, State, or Tribal Law (including threatened or endangered 

species) that are in the vicinity of the cooling water intake structure(s) and are 

susceptible to impingement...”; 

(ii)”A characterization of all life stages....including a description of the abundance and 

temporal and spatial characteristics in the vicinity of the cooling water intake 

structure(s), based on sufficient data to characterize annual, seasonal, and diel 

variations in impingement mortality......These may include historical data that are 

representative of the current operation of your facility and of biological conditions at the 

site”; 

(iii)”Documentation of the current impingement mortality.....of all life stages....and an 

estimate of impingement mortality....to be used as the calculation baseline...... 

Impingement mortality.....samples to support the calculations......must be collected 

during periods of representative operational flows for the cooling water intake structure 

and the flows associated with the samples must be documented.” 
10735-002-400 August, 2005 3-2

Figure 3-1 presents a complete list of all the fish species identified in the Garrison Reach from 

1991 through 20031

. Figure 3-2 presents the number of each species identified at the Stanton 

Station by North Dakota Game and Fish during sampling events in summer and in fall from 1997 

through 2004. The second condition listed above will be addressed by the data collected by North 

Dakota Game and Fish since it is likely that fish populations and movement were at their highest 

levels in the months that were sampled. The impingement characterization study will provide 

additional species occurrence data for the entire year. The existing data have been used to 

identify the species of fish likely to be found during the impingement characterization study and 

will be utilized to analyze the potential impact of impingement in the study report and during 

completion of the CDS. Additional data collected by North Dakota Game and Fish and other 

organizations will be incorporated into the study as soon as it is made available. 

The U.S. Fish and Wildlife Service has reportedly documented the occasional presence of the 

pallid sturgeon, an endangered species, in the Garrison Reach. While it is not expected that a 

pallid sturgeon specimen will be collected, it is possible. The U.S. Fish and Wildlife Service will be 

immediately contacted if such a specimen is collected and it will be provided to them for 

examination after it is documented for this study. 

The data collected by North Dakota Game and Fish as well as other researchers provide a 

relevant and ongoing characterization of the biological conditions and populations in the river near 

the intake structures of the three power plants. The data are representative of current conditions 

and were collected using appropriate QA/QC procedures by agencies of the State of North 

Dakota. The Impingement Characterization Study as described in this Plan will comply with the 

third condition listed above and will complete the data set required by the rule. The applicants do 

not propose to collect additional source water body data. 

 

1 North Dakota Fisheries Investigations, Aquatic Investigations of the Missouri Mainstream in North Dakota, by Jeff 

Hendrickson, North Dakota Game and Fish Department, March 2004.

10735-002-400 August, 2005 3-4

Total Number of Each Fish Specie Present at 

Stanton Sampling Site 

NDG&F Sampling 1997 – 2004 

 Summer Fall 

Bigmouth Buffalo 15 160 

Black Bullhead 0 0 

Black Crappie 0 0 

Bluegill 0 0 

Blue Sucker 15 8 

Brown Trout 2 25 

Brook Stickleback 0 0 

Burbot 1 6 

Common Carp 84 125 

Channel Catfish 11 7 

Cisco 0 7 

Common Shiner 9 0 

Cutthroat Trout 16 5 

Emerald Shiner 39 142 

Chinook Salmon 15 7 

Fathead Minnow 0 1 

Freshwater Drum 5 5 

Goldeye 11 8 

Golden Shiner 0 0 

Johnny Darter 4 39 

Largemouth Bass 0 0 

Longnose Dace 0 1 

Longnose Sucker 100 103 

Northern Pike 25 8 

Orange Spotted Sunfish 0 0 

Paddlefish 3 0 

Rainbow Smelt 3 14 

Rainbow Trout 1 4 

River Carpsucker 330 295 

Smallmouth Buffalo 8 43 

Sauger 38 34 

Shorthead Redhorse 140 65 

Smallmouth Bass 9 7 

Shortnose Gar 3 7 

Shovelnose Sturgeon 4 7 

Spottail Shiner 0 3 

Walleye 264 203 

White Bass 50 38 

White Sucker 389 409 

Western Silvery Minnow 0 1 

Yellow Perch 0 3 

Totals 1,594 1,790 

Figure 3-2. Summary of Fish Collected at Stanton Station 1997-2004 
10735-002-400 August, 2005 4-1

4.0 FIELD AND LABORATORY PROCEDURES 

Impingement sampling will begin in June 2005 and will continue for 1 year. For the first 3 months 

of the study, each of the three river intakes will be visited once every 2 weeks for collection 

activities. During each visit, two continuous (approximate) 12-hour biological samples will be 

collected. 

During each impingement sampling event, the operating vertical traveling screens will be rotated 

per each station’s standard operating procedures. Prior to the first 12-hour sampling period, plant 

operators will rotate and wash the screens and sluiceways to remove all existing debris and 

material. At the start of each sampling period, a metal basket with 3/8-inch square mesh will be 

placed in the sluiceway downstream of the traveling screens. The collection basket will be 

designed to fit precisely within the sluiceway so that all wash water containing fish and debris will 

travel through the basket and not around it, to ensure a complete sample. An approximate 

representation of the basket placement is shown in Figure 4-1; there will be slight variations of 

design and location depending on each station’s traveling screen operation. Plant operators will 

wash the traveling screens according to normal plant conditions. Because of the time needed to 

1) wash the screens, 2) remove debris and fish from the collection baskets, and 3) travel between 

facilities, it will not be possible to collect samples representing exactly 12 hours. However, the 

total collection period will be approximately 24 hours and the actual collection times will be noted 

on the field data sheets. 

At the end of the first 12-hour period, screens will be rotated and washed, with debris being 

retained by the collection basket. As water passes through the basket, sampling personnel will 

remove fish. After the screens have been washed, any remaining debris in the basket will be 

examined for fish. The basket will be cleaned and put back in place for the second 12-hour 

collection period. At the end of the second 12-hour period, the screens need to be washed (due to 

excessive buildup of debris and subsequent pressure drop of the cooling water stream), prior to 

completion of the 12-hour period, wash water will be passed through the basket and examined for 

fish; the intermediate washing will be documented. If debris buildup is extremely heavy and it is 

not possible to intercept all of the wash water, the time the wash occurred will be noted and the 

actual collection time will be documented on the field data sheet. Plant personnel will be trained 

and utilized for collection of fish if intermediate washing is required. Specimens will be kept in 

coolers until sampling personnel return to the site. 

Fish will be separated from the debris, placed on ice, and examined soon after collection or 

transported in coolers back to Bismarck for evaluation. Fish that are dead (no visible movement of 

gills or fins) at collectiojn will be noted on data sheets (placed in a separate container, if 

necessary). Fish that may have been dead long before impingement (e.g., advanced 

10735-002-400 August, 2005 4-3

decomposition, missing scales and eyes, excessive fungus, etc., as compared to other fish within 

a particular sample) will be noted on the laboratory data sheet. Fish will be identified by species, 

weighed (grams), and measured (minimum of total length in centimeters). All fish identifications 

will be conducted by experienced fisheries biologists, utilizing current taxonomic keys or 

publications. Since it is expected that the fish count for each collection event will be well below 

100 individuals, each fish will be evaluated and counted. If there is an exceptionally large number 

of individuals of one or more species, and the total number of specimens collected exceeds 100, 

then subsampling will be allowed. For any one species, at least 20 individuals must be measured; 

these will be obtained in an unbiased fashion from the pool of available specimens. Unusually 

large or small specimens also will be measured. Biological metrics will not be collected on the 

remaining fish. 

All fish from any given collection (i.e., from one plant during one collection period) will be digitally 

photographed (as a group) using a camera with a minimum resolution of 3.0 megapixels. All 

digital photographs will be stored on a CD and submitted with an annotated list at the end of the 

study period. A voucher collection will be made that will include at least one representative of each 

species. The representative specimen should be in good condition with little or no external 

damage. Voucher specimens may be frozen or stored in formalin/alcohol. Only one specimen 

from each species is needed in the voucher collection; all other collected fish can be discarded, 

unless they are being retained for quality assurance purposes (see Quality Assurance/Quality 

Control [QA/QC] Procedures). Unusual fish (fish with odd coloration, tumors, unidentified fish) will 

be kept in the voucher collection as well. 

After three months of data are collected at the three intakes, the data among the stations will be 

compared for sample taxonomy, quantity, and general biological metrics. After the first quarter, 

the data will be presented to NDDH. If the data from the three stations are similar, a request will 

be made to NDDH to conduct biweekly sampling at one station for three more quarters with a 

single verification sampling event at the other two stations (conducted during the same week as 

the routine sampling event) once each quarter. At this time, it is proposed that the LOS be 

selected as the primary sampling location since its configuration is most similar to baseline. If the 

quarterly samples reveal a significant difference in quantity or taxonomy at either station, then 

biweekly sampling will be resumed at that station for the next quarter. The total study will 

encompass 26 sampling events or approximately one year. Figure 4-2 shows the proposed 

schedule of sampling events for the sampling year (dates shown are tentative and may be slightly 

modified due to weather or operating constraints). 

Sampling will be conducted by WPC, a local environmental consulting firm and supervised by 

Dr. David Pillard, of ENSR. Dr. Steve Kelsch will be a technical advisor and will provide support 

for taxonomic identification and quality assurance. Figure 4-3 provides details on the sampling 

staff organization. 
ID Task Name

1 Meeting with NDDH2 Sampling Plan Approval3 Quarterly Data Evaluations8 Sample and Data Collection9 Leland Olds Station

36 Milton R. Young Station (first 3 months)44 Milton R. Young Station57 Stanton Station (first 3 months)65 Stanton Station

5/26

6/2

15 22 29 5 12 19 26 3 10 17 24 31 7 14 21 28 4 11 18 25 2 9 16 23 30 6 13 20 27 4 11 18 25 1 8 15 

June July August September October November December January 

2005 

Impingement Monitoring Study (Tentative)

Page 1
Study Leader

Dr. Dave Pillard

(ENSR)

Figure 4-3

Impingement Study Team

Sampling Team Leader

John Schulz

(WPC)

Sampling Staff

Al Sandvol

(WPC)

Basin Electric

Great River Energy

Minnkota Power Cooperative

Technical Advisor

Dr. Steve Kelsch

University of North Dakota
10735-002-400 August, 2005 5-1

5.0 DATA ANALYSIS 

5.1 Fish Data 

Field and laboratory data for each sample will be recorded on forms compatible for computer 

entry. Data will be entered into a spreadsheet after each collection event and will be compared 

against the hard copy laboratory data forms by a data analyst with experience in biological data 

collection. Errors will be corrected immediately. Since counts are expected to be low, there should 

be no need for data extrapolation. Data will be reviewed for consistency by QA/QC personnel at 

ENSR. Data anomalies will be identified and investigated before being accepted as valid and 

usable. 

Summaries of the number for each species collected will be presented in the spreadsheet by 

sampling period and by station. 

5.2 Plant Operating Data 

For each sampling period, hourly data regarding the number of circulating water pumps in 

operation per unit, use of warm water recirculation, plant load (MW), and intake temperature will 

be collected from plant personnel. Hourly cooling water volumes will be calculated based on the 

number of pumps in operation for each unit and then summed across each 24-hour sampling 

period to determine the total volume sampled. Daily cooling water volumes also will be obtained 

from plant personnel in order to calculate weekly cooling water volumes. 

In addition, a velocity reading will be taken at each intake during each sampling event using a 

hand-held velocity meter. The meter will be positioned, if possible, near the front of the forebays 

for a prescribed interval of time and the velocity will be measured. If access to the forebays is not 

possible, than velocity will be measured at another accessible location, possible upstream of the 

screens. The river stage or depth of water at the screens will be recorded by plant operators or by 

the sampling team – this information will be used to evaluate impingement data. 

Other operating data that will be collected include the number of wash events during the sampling 

period and the number of times the collection basket was emptied, if required to maintain 

adequate flow through the screens or to keep the basket from overflowing or plugging. 
10735-002-400 August, 2005 5-2

5.3 Impingement Estimates 

Species-specific impingement estimates will be calculated on a weekly basis using the following 

formula: 

Weekly Estimate = Number of Fish Collected x Weekly Cooling Water Volume 

 Cooling Water Volume Sampled 

Weekly impingement estimates (sampled on a biweekly basis) will be multiplied to determine a 

monthly total estimate. At the end of the study, monthly frequency distributions will be developed 

for each species sampled. Confidence intervals and limits will be determined at the end of the 

study using appropriate statistical and data evaluation methods. 
10735-002-400 August, 2005 6-1

6.0 QUALITY ASSURANCE/QUALITY CONTROL PROCEDURES 

Prior to initiating monitoring, a detailed QA/QC Plan will be developed to ensure that accurate, 

consistent and traceable data are collected for the duration of the project. Elements of the QA/QC 

Plan can roughly be broken into five categories: 

• Mobilization for Field Work; 

• Sample Collection; 

• Sample Processing; 

• Data Management; and 

• Sample Tracking. 

6.1 Mobilization 

Sampling will be conducted in accordance with the described biweekly schedule. A matrix will be 

developed showing target dates for conducting each component of the program. The matrix will 

include the time(s) of day sampling is to be performed. Designated plant contacts will be notified 

1 week prior to each sampling event, with confirmation provided 24 to 48 hours in advance. 

A Field Manager, Mr. John Schulz of WPC, Inc., in Bismarck, North Dakota, has been assigned to 

the project. It will be the responsibility of the Field Manager to ensure that all needed equipment 

and supplies are readied for each sampling event and that the gear is in proper operating 

condition. The Field Manager will develop a checklist of primary and backup equipment, supplies, 

datasheets, tools, field repair kits, safety equipment, and other necessary items for each type of 

sampling activity. Twenty-four hours prior to each sampling event, this gear will be assembled and 

verified against the checklist. To the extent practical, backup gear, replacement parts, and spare 

batteries will be included in the gear assembled for each sampling event. 

The sampling team assigned by the Field Manager will review field safety issues and protocols 

prior to embarking on each trip. Each sampling team will be led and supervised by the Sampling 

Team Leader, who will be either Mr. Schulz or Mr. Al Sandvol of WPC, Inc. The Sampling Team 

Leader (if different from the Field Manager for any given sampling event) will meet with the Field 

Manager and review procedures, target plants, and schedule. They also will review a list of plant 

personnel who will be on duty during the collection period. It is the responsibility of the Field 

Manager and sampling team to ensure that all assembled equipment is transported to the project 

site and properly stored and handled for the duration of the trip. 
10735-002-400 August, 2005 6-2

Upon return from each sampling event, the Field Manager will ensure that all gear is cleaned, 

inspected, stored, repaired when necessary, and otherwise readied for the next event. Supplies 

will be restocked, as necessary. 

6.2 Sample Collection 

The Sampling Team Leader will be responsible for ensuring that all field activities are conducted 

in conformance with established standard operating procedures (SOPs) and safety procedures. 

The Sampling Team Leader will be responsible for ensuring that all mobile equipment and 

samples are returned in proper order to WPC for analysis. A Scientific Collection Permit will be 

obtained from North Dakota Game and Fish (NDGF) to allow the collection and transport of fish 

once they are removed from the baskets at each facility. In the unlikely event that a threatened or 

endangered (T&E) species would be collected, the specimen will be retained for examination by 

NDGF and the U.S. Fish and Wildlife Service (USFWS). However, no additional permit or plan is 

required relative to the possibility of encountering a T&E species.

6.3 Recording Data 

Recorded data represent the results of long hours spent in the field and are the first step in a 

lengthy analytical process. All field and laboratory personnel will adhere to the basic rules for 

recording information as described below: 

• Legible writing in black, waterproof ink only with no erasures, write-overs, or cross-outs; 

• Correction of errors with a single strike-out line followed by the recorder’s initials and date; 

• Initialed and dated footnotes at the bottom of each page if further explanation of any 

corrections is needed; and 

• Cross-outs on incomplete pages with an initialed and dated diagonal line. 

6.4 Datasheets 

All data will be entered on pre-printed, standardized datasheets at the time of sampling. 

Datasheets will be water proof, “Rite in the Rain®” or equivalent. Generic information, such as 

date, type of sampling, field team members, and weather conditions, will be included at the top of 

the form. Site-specific conditions, such as time of collection, physical parameters, and sample ID, 

will be recorded at the beginning of sample collection. Upon completion of sample collection, any 

unusual conditions that might have affected the quality of the sample will be documented. An 
10735-002-400 August, 2005 6-3

explanation will be provided for any missing data. The datasheet will then be checked for 

accuracy by a second member of the field team prior to obtaining additional samples or moving to 

the next station. Any unusual physical conditions of the collection basket or area (e.g., broken 

basket) should be noted and documented with digital photographs. 

6.5 Container Labeling 

Biological samples will be placed in appropriate containers. Containers will be labeled with a 

sparate “stick-on” label or with a water-proof, felt-tip marker (e.g., Sharpie® ). The label will 

include, at a minimum the date and station ID (including Unit, if the plant has more than one unit), 

and whether fish were alive (visible movement) or dead at the time of collection. Additional 

information may include sample type, sample number, and sampler’s initials. If samples will need 

to be stored for several days before processing, than the latter information must also be recorded. 

6.6 Safety Precautions 

Appropriate safety gear will be worn and utilized for all field activities in accordance with plant 

safety rules and established safety plans. 

6.7 Collection of Biological Data 

At the lab, field samples will be logged in, sorted by date and type, and stored in a safe, secure 

location for processing. Appropriate reference literature and electronic databases will be made 

available to assist in taxonomic determinations. At least once per month for the first quarter and 

once per quarter for the remaining project time, fish collected form at least one of the plants (no 

less than 20 fish or all fish if <20 collected) will be reviewed by a second qualified taxonomist to 

ensure consistency in identifications. Should there be disagreement between the two taxonomists, 

supporting confirmation from outside experts will be sought. Samples of all problematic taxa will 

be delivered to an independent expert for identification/verification. 

Length measurements of fish will be made using a measuring board consisting of a linear metric 

scale secured to a flat wooden or plastic base with a fixed head piece. Fish will be measured by 

positioning the body on the right side, head facing the observer’s left, and fish mouth closed. Total 

length will be measured as the distance from the anterior-most portion of the head or jaws to the 

extreme tip of the caudal fin. If the caudal fin is bi-lobed, the lobes will be squeezed together and 

measured to the posterior most tip of the combined lobes. Standard length will be measured from 

the anterior-most portion of the head or jaws to the hypural plate (posterior most portion of the 

caudal region). 
10735-002-400 August, 2005 6-4

Representative specimens of problematic species will be identified to the lowest practicable taxon 

and preserved for more thorough identification. Freezing is adequate for short-term preservation, 

provided freezing will not distort the body as to make it difficult to identify. For longer-term storage, 

a chemical preservative is preferred. For fish greater than 150 mm that are being preserved 

chemically, an incision about 30 mm in length will be made along the abdominal body wall on the 

right side of the fish to ensure penetration of fixative into the body cavity. Fish will remain in 

buffered formalin (10 percent with CaCO3) for several days to ensure adequate fixation of tissues. 

After the fish have been thoroughly fixed, the buffered formalin will be removed and the 

specimens soaked in fresh water for 48 hours with at least one change of water. After 48 hours all 

water will be discarded and 40-percent isopropyl alcohol or 70-percent ethanol added to the 

collection container for permanent preservation. 

All data generated during the processing of samples will be recorded on standardized lab bench 

sheets. Prior to processing each sample, pertinent information on the container labels will be 

transferred to the bench sheet to ensure proper sample tracking. If the sample is to be reviewed 

as part of the project QA process, it be labeled with a discrete sample number and the name of 

the processing taxonomist and stored for QA purposes until the data for that sampling event can 

be evaluated. Once a QA review is conducted and the data are acceptable, the sample will be 

disposed of. If the data are not acceptable (e.g., due to errors or anomalies inconsistent with 

previous data), the QA reviewer and the original taxonomist will reexamine the data and 

determine the cause of any discrepancies. The QA reviewer will then document the discrepancy 

and steps taken towards resolution and prevention of the future errors. In addition, if data from 

any event are deemed unacceptable, a sample from the next event will be retained for QA review, 

even if samples from that event were not scheduled to be examined by a second taxonomist. 

reexamination of a representative number of previously identified samples will be made by a 

different taxonomist to verify previous identifications and numerical information. Greater than 

5 percent discrepancy in taxonomic identification between initial and QA analyses will require 

reexamination of all samples from a particular sampling event. Discrepancies in numerical 

information (weight and length) will be interpreted in light of changes associated with storage 

methods (e.g., shrinkage due to preservatives). However, suspicious discrepancies in biological 

metrics also will necessitate a reexamination of all samples from that particular sampling event. 

6.8 Deviations from QA/QC Plan or SOP 

Examples of failures in sampling methods and/or deviations from sampling requirements include 

but are not limited to such things as sample container spillage or breakage, gear malfunction, 

equipment failure, and unusual site conditions that prevent sampling. Failures or deviations from 

the QA/QC Plan or SOP will be fully documented on the field datasheet and reported to the 

Project Manager. The Project Manager will determine if the deviation from established protocol 
10735-002-400 August, 2005 6-5

compromises the validity of the resulting data. The Project Manager will decide whether to accept 

or reject data associated with the sampling event based on his/her best professional judgment 

and will determine whether the absence of specific data will significantly affect analytical 

objectives of the project. In cases where missing data are likely to impact the ability of the project 

team to draw reliable inferences regarding plant effects, the Project Manager will require that 

sampling be repeated. 

6.9 Data Management 

Field datasheets and lab bench sheets will be placed in labeled folders for input into an electronic 

database maintained by the identification lab. Prior to study initiation, the Field Manager or 

assignee will review the forms for completeness and accuracy. If it becomes apparent early in the 

project that additional data need to be collected, the data sheets will be modified appropriately. 

Each form will have a signature and date block to track data processing. After the data have been 

entered into the database, the data forms will be signed, dated, and returned to the folder for 

verification. Printouts of entered data will be verified against corresponding field datasheets and 

lab bench sheets to ensure that all information has been accurately transferred. Missing 

information will be added and inaccurate information corrected. The forms will be initialed and 

dated by the verifying party. Following data verification, the original data forms will be segregated 

by sampling date and type and archived for the life of the project. 

6.10 Sample Tracking 

Proper sample handling and custody procedures are required to ensure the integrity of samples 

from sample collection through data analysis. For samples collected by field personnel, that do not 

leave the possession of field personnel/taxonomists, no custody documentation is required other 

than collection data documented on field and laboratory data sheets. However, if samples are 

retained for QA purposes and those samples are sent via courier to another location, a number of 

forms will be used for chain-of-custody documentation. Upon arrival at the laboratory for QA 

examination, all samples will be received and logged in using a Sample Receipt Log, which will 

include the following information: 

• Project Name; 

• Field Team Leader; 

• Date of Collection; 

• Time of Collection; 

• Site Identification; 

• Type of Sample; 

• Name of collector(s); 
10735-002-400 August, 2005 6-6

• Name of Recipient; and 

• Time/Date of Receipt. 

The Project Manager or assignee will develop a master list of all samples, which will be used to 

track the progress of the field sampling program. Appropriate blocks for each sample will be 

checked off as each sample is collected, processed, analyzed, and the data entered into the 

computer. Each month, the Project Manager will review the master list and evaluate whether 

sample collection and processing is progressing in conformance with established schedules. 

Missing information will be reconciled and appropriate corrective measures taken, where 

warranted. 

All failures associated with sample receipt procedures will be immediately reported to the Project 

Manager. These include but are not limited to things such as lost samples, deviations from SOP 

and/or QA/QC requirements, incomplete documentation, possible tampering of samples, and 

broken or spilled samples. The Project Manager will determine if these issues have compromised 

the validity of the resulting data or will impede analytical objectives. The Project Manager will 

decide how best to address identified problems. Possible courses of action include 1) document 

and proceed, 2) redo the entire sampling event, or 3) selectively analyze the samples. The 

effect(s) of all identified problems on project objectives and any related corrective measures will 

be documented in QA reports furnished to the client. 
10735-002-400 August, 2005 7-1

7.0 STUDY REPORT 

When this study is completed, a report will be prepared which includes field and laboratory 

methodologies, raw data, monthly organism and operating data summaries, and detailed results 

and conclusions sections. This report will become part of each station’s Comprehensive 

Demonstration Study (CDS) and will be used to support the stations’ selected compliance 

program. 
APPENDIX A 

BIBLIOGRAPHY 
BIBLIOGRAPHY 

Berry, C. R. and B. A. Young. 2001. Introduction to the benthic fishes study. Volume 1 of Population 

structure and habitat use of benthic fishes along the Missouri and lower Yellowstone rivers. 

U.S. Geological Survey, Cooperative Research Units, South Dakota State University, 

Box 2140b, Brookings, South Dakota 57007. charles_berry@sdstate.edu. 

Berry, C. R., D. L. Galat, and M. L. Wildhaber. 2001. Fish distribution and abundance. Volume 3 of 

Population structure and habitat use of benthic fishes along the Missouri and Yellowstone 

rivers. U.S. Geological Survey, Cooperative Research Units, South Dakota State University, 

Box 2140b, Brookings, South Dakota 57007. charles_berry@sdstate.edu. 

Dieterman, D. J., M. P. Ruggles, M. L. Wildhaber, and D. L. Galat, editors. 1996. Population Structure 

and Habitat Use of Benthic Fishes Along the Missouri and Lower Yellowstone Rivers. 1996 

Annual Report of Missouri River Benthic Fish Study PD-95-5832 to U.S. Army Corps of 

Engineers and U.S. Bureau of Reclamation. 

Dieterman, D.J. 2000. Spatial Patterns in Phenotypes and Habitat Use of Sicklefin Chub, 

(Macrhybopsis meeki) in the Missouri and Lower Yellowstone Rivers. Doctoral Dissertation, 

University of Missouri-Columbia, Columbia, MO 185 p. 

Everett, S. R., D. L. Scarnecchia, and L. F. Ryckman. 2004. Distribution and habitat use of sturgeon 

chubs (Macrhybopsis gelida) and sickle-fin chubs (M. meeki) in the Missouri and Yellowstone 

Rivers, North Dakota. Hydrobiologia 527: 183-193. 

Galat, D. L., M. L. Wildhaber, and D. J. Dieterman. 2001. Spatial patterns of physical habitat. Volume 

2 of Population structure and habitat use of benthic fishes along the Missouri and lower 

Yellowstone rivers. U.S. Geological Survey, Cooperative Research Units, University of 

Missouri, 302 ABNR Bldg., Columbia, Missouri 65251-7240. galatd@missouri.edu. 

Galat, D., R. White, C. Pierce, L. Sappington, D. Scarnecchia, M. Ruggles. Missouri River Benthic 

Fish Study. http://wfs.sdstate.edu/units/fishes.html. 8 pp. 

Hendrickson, J. C. 2004. North Dakota Fisheries Investigations. Aquatic Investigations of the Missouri 

Mainstem in North Dakota. Report of the North Dakota Game & Fish Department, Bismarck, 

North Dakota: 85 pp. 

Hesse, L. W., J. C. Schmulbach, J. M. Carr, D. D. Keenlyne, D. G. Unkenholz, J. W. Robinson, G. E. 

Mestl. 1989. Missouri River Fishery Resources in Relation to Past, Present, and Future 

Stresses, p. 352-371. In D.P. Dodge [ed.] Proceedings of the International Large River 

Symposium. Can. Spec. Publ. Fish. Aquat. Sci. 106. 

Hesse, L. W. and W. Sheets. 1993. The Missouri River Hydrosystem. Fisheries 18(5): 5-14. 
Neel, J. K. 1978. Life in the Missouri River with Warming by 676 Megawatts Gross Steam Generated 

Power Production. Prepared for Basin Electric Power Cooperative. 

Pegg, M. A. 2000. Hydrological variation along the Missouri River and its effect on the fish community. 

 Doctoral Dissertation, Iowa State University, Ames, IA. 141 pp. 

Pierce, C. L., C. S. Guy, P. J. Braaten, and M. A. Pegg. 2001. Fish growth, mortality, recruitment, 

condition and size structure. Volume 4 of Population structure and habitat use of benthic fishes 

along the Missouri and lower Yellowstone rivers. US. Geological Survey, Cooperative 

Research Units, Iowa State University, Science Hall II, Ames, Iowa 50011. 

cpierce@iastate.edu. 

Power, G. 1993. The Missouri River System’s “Other” Fish. ND Outdoors, August, p. 6-9. 

Power, G., J. C. Hendrickson, J. D. Lee, and F. Ryckman. 1994. North Dakota Fisheries Investigations, 

Missouri River System Fishery Reference and Operational Management Document. NDG and 

F Dept., 100 North Bismarck Expressway, Bismarck, ND, 58501-5095. 72 pp. 

Power, G. 1995. River Fish. ND Outdoors, March, p. 13. 

Power, G. 1998. The Missouri River in North Dakota (Garrison Reach) – A Report to the Director, 

Official Department Position Papers, Game and Fish Department, North Dakota: 7 pp. 

Welker, T. L. 2000. Ecology and Structure of Fish Communities in the Missouri and Lower 

Yellowstone Rivers. Doctoral Dissertation, University of Idaho, Moscow, ID. 232 p. 

Young, B. A., T. L. Welker, M. L. Wildhaber, C. R. Berry, and D. Scarnecchia, editors. 1997. 

Population Structure and Habitat Use of Benthic Fishes along the Missouri and Lower 

Yellowstone Rivers. 1997 Annual Report of Missouri River Benthic Fish Study PD-95-5832 to 

the U.S. Army Corps of Engineers and the U.S. Bureau of Reclamation. 

Young, B. A. 2001. Intraspecific Variation among Emerald Shiners (Notropis atherinoides) of the 

Missouri River. Doctoral Dissertation, South Dakota State University, Brookings, SD. 140 p. 
December 2006

Document No.: 10735-002-400

Appendix D 

Bibliography of Sources Used for Source Water Body Review 
December 2006

Document No.: 10735-002-400

Berry, C. R. and B. A. Young. 2001. Introduction to the benthic fishes study. Volume 1 of Population structure 

and habitat use of benthic fishes along the Missouri and lower Yellowstone rivers. U.S. Geological Survey, 

Cooperative Research Units, South Dakota State University, Box 2140b, Brookings, South Dakota 57007. 

charles_berry@sdstate.edu. 

Berry, C. R., D. L. Galat, and M. L. Wildhaber. 2001. Fish distribution and abundance. Volume 3 of Population 

structure and habitat use of benthic fishes along the Missouri and Yellowstone rivers. U.S. Geological 

Survey, Cooperative Research Units, South Dakota State University, Box 2140b, Brookings, South Dakota 

57007. charles_berry@sdstate.edu. 

Dieterman, D. J., M. P. Ruggles, M. L. Wildhaber, and D. L. Galat, editors. 1996. Population Structure and 

Habitat Use of Benthic Fishes Along the Missouri and Lower Yellowstone Rivers. 1996 Annual Report of 

Missouri River Benthic Fish Study PD-95-5832 to U.S. Army Corps of Engineers and U.S. Bureau of 

Reclamation. 

Dieterman, D.J. 2000. Spatial Patterns in Phenotypes and Habitat Use of Sicklefin Chub, (Macrhybopsis 

meeki) in the Missouri and Lower Yellowstone Rivers. Doctoral Dissertation, University of MissouriColumbia, Columbia, MO 185 p. 

Everett, S. R., D. L. Scarnecchia, and L. F. Ryckman. 2004. Distribution and habitat use of sturgeon chubs 

(Macrhybopsis gelida) and sickle-fin chubs (M. meeki) in the Missouri and Yellowstone Rivers, North 

Dakota. Hydrobiologia 527: 183-193. 

Galat, D. L., M. L. Wildhaber, and D. J. Dieterman. 2001. Spatial patterns of physical habitat. Volume 2 of 

Population structure and habitat use of benthic fishes along the Missouri and lower Yellowstone rivers. 

U.S. Geological Survey, Cooperative Research Units, University of Missouri, 302 ABNR Bldg., Columbia, 

Missouri 65251-7240. galatd@missouri.edu. 

Galat, D., R. White, C. Pierce, L. Sappington, D. Scarnecchia, M. Ruggles. Missouri River Benthic Fish Study. 

http://wfs.sdstate.edu/units/fishes.html. 8 pp. 

Hendrickson, J. C. 2004. North Dakota Fisheries Investigations. Aquatic Investigations of the Missouri 

Mainstem in North Dakota. Report of the North Dakota Game & Fish Department, Bismarck, North Dakota: 

85 pp. 

Hesse, L. W., J. C. Schmulbach, J. M. Carr, D. D. Keenlyne, D. G. Unkenholz, J. W. Robinson, G. E. Mestl. 

1989. Missouri River Fishery Resources in Relation to Past, Present, and Future Stresses, p. 352-371. In 

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Appendix E 

Agency Consultation Documentation