Appendix E

Folsom DS/FDR Revised Draft 

Fish and Wildlife Coordination Act Report








 REVISED DRAFT 

FISH AND WILDLIFE 

COORDINATION ACT 

REPORT 

FOLSOM DAM SAFETY AND FLOOD DAMAGE 

REDUCTION PROJECT 

P R E P A R E D B Y : 

S A C R A M E N T O F I S H A N D W I L D L I F E O F F I C E 

F I S H & W I L D L I F E S E R V I C E 

S A C R A M E N T O , C A L I F O R N I A 

M A R C H 2 0 0 7 
Revised Draft- Subject to Change 2

TA B L E O F C O N T E N T S 

Executive Summary.....................................................................................................................................................3

Introduction .................................................................................................................................................................7

Description of the Project area...................................................................................................................................8

Description of the Project Alternatives......................................................................................................................8

No Action Alternative................................................................................................................................................8

Construction Alternatives..........................................................................................................................................9

Alternative 1- No Dam Raise/ Minimal Embankment Raise/ Fusplug Auxiliary Spillway .................................17

Alternative 2 – Four- Foot Dam/Embankment Raise/ Fuseplug Auxiliary Spillway with Tunnel .....................17

Alternative 3- Three and a Half Foot Dam/Embankment Raise/ Six-Submerged Tainter Gate Spillway ..........17

Alternative 4- Seven-Foot Dam/Embankment Raise/ Six-Submerged Tainter Gate Spillway ............................17

Alternative 5- Seventeen-Foot Dam/Embankment Raise/ No Spillway................................................................18

Biological Resources..................................................................................................................................................18

Existing conditions..................................................................................................................................................18

Future Conditions without the Project....................................................................................................................21

Future Conditions with the Project.........................................................................................................................23

Discussion ...................................................................................................................................................................30

Recommendations......................................................................................................................................................38

Literature Cited .........................................................................................................................................................42

Appendix A- HEP Report .........................................................................................................................................44

Appendix B-Federally listed species.......................................................................................................................178

Appendix C-Impacted Acres by Cover-type .........................................................................................................181

Appendix D-FWCAR for the American River Watershed Investigation Folsom Dam Outlet Modification 

Project ......................................................................................................................................................................183 

Appendix E-Habitat Impact Maps.........................................................................................................................233
Revised Draft- Subject to Change 3

FOLSOM DAM SAFETY AND FLOOD DAMAGE REDUCTION PROJECT 

EXECUTIVE SUMMARY 

The U.S. Bureau of Reclamation (Reclamation) and the U.S. Army Corps of Engineers (Corps) 

are currently evaluating alternatives for the Folsom Dam Safety and Flood Damage Reduction 

(Folsom DS/FDR) project. This is one of many projects being pursued by the Corps under the 

authority of the American River Watershed Investigation. Reclamation is evaluating dam safety 

at the Folsom Facilities through their Safety of Dams Program. Reclamation recognizes the need 

to expeditiously implement engineering measures for the Folsom Facilities in order to reduce 

potential failure due to seismic, static, and hydrologic conditions. The Corps recognizes the need 

to incrementally increase minimum flood protection through increasing flood storage capacity 

and/or reservoir pool release mechanisms. Therefore, Congress modified the existing authorities 

under the Energy and Water Appropriations Act of 2006, which directed the Secretary of the 

Army and the Secretary of the Interior to collaborate on authorized activities to maximize flood 

damage reduction improvements and address dam safety needs at Folsom Dam and Reservoir as 

one Joint Federal Project. The project objectives are: 

o Expeditiously reduce hydrologic risk of overtopping-related failure of any impoundment 

structure during a probable maximum flood (PMF) event in accordance with 

Reclamation’s Public Protection Guidelines; 

o Expeditiously reduce the risk of structural failure of any impoundment structure during a 

potential seismic event in accordance with Reclamation’s Public Protection Guidelines; 

o Expeditiously reduce the risk of structural failure of any impoundment structure during a 

potential static event in accordance with Reclamation’s Public Protection Guidelines; and 

o Expeditiously improve the flood damage reduction capacity of the facilities in a manner 

consistent with existing Corps authorities. 

The project area encompasses primarily Federal lands in and around Folsom Reservoir and 

Folsom Dam, including parts of both the north and south forks of the American River. 

The Folsom Facilities to be addressed by one or more of the engineering options include the 

main concrete dam, the right and left wing dams, Mormon Island Auxiliary Dam (MIAD), and 

eight dikes (1 through 8). The concrete dam and earthen wing dams serve to impound water 

associated with the main stem of the American River. MIAD was built within an historic river 

channel, while the earthen dikes serve to contain water at low spots in the topography during 

periods when the reservoir is full or nearly full. 
Revised Draft- Subject to Change 4

This project identifies unique opportunities to expedite Federal funds for planning, design and 

implementation of a flood control and dam safety risk reduction action. Reclamation and the 

Corps analyzed five action alternatives along with the no action alternative before choosing a 

Preferred Alternative that considers the current hydrologic, seismic, static, and flood damage 

risks posed by the Folsom Facilities. 

The five action alternatives include designs for an auxiliary spillway, enlargement of the 

reservoir (a dam raise) as well as several construction zones, and borrow and stockpile areas. 

The four auxiliary spillway designs being evaluated are a fuseplug, fuseplug with a tunnel, a 

four-submerged tainter gate and a six-submerged tainter gate spillway. The five reservoir 

enlargement designs being evaluated include: minimal to 4-foot embankment raise, 3.5-foot 

parapet wall raise, 4-foot embankment raise, 7-foot embankment raise and a 17-foot 

embankment raise. 

The U.S. Fish and Wildlife Service (Service) has evaluated the potential fish and wildlife 

impacts of all five alternatives proposed under the Folsom DS/FDR project. This report 

contains an evaluation of the adverse impacts to important fish and wildlife resources of the 

various alternatives outlined in the Folsom Dam Safety and Flood Damage Reduction, Final

Environmental Impact Statement/ Environmental Impact Report, March 2007. 

The recommendations in this report constitute what the Service believes, from a fish and wildlife 

resource perspective and consistent with our Mitigation Policy, to be the best present 

recommendations for the project. The outcome of consultation under section 7 of the 

Endangered Species Act or future consultations under the Fish and Wildlife Coordination Act, 

could affect the recommendations herein. 

The Service recommends that Reclamation and the Corps: 

o Select a flood control alternative which avoids, to the extent possible, 

unmitigable impacts and minimizes other impacts to fish and wildlife resources. 

o Consult with the Service and the National Marine Fisheries Service pursuant to 

section 7 of the Endangered Species Act, to minimize adverse affects to 

federally listed species and their habitats. 

o Consult with the California Department of Fish and Game regarding potential 

impacts to State listed threatened and endangered species. 

o Avoid impacts to oak-grey pine woodland, riparian areas and seasonal wetlands 

adjacent to, but outside of, construction easement areas through use of 

construction fencing. 

o Avoid impacts to woody vegetation at all staging areas, borrow sites, and haul 

routes by enclosing them with fencing. 

o Avoid impacts to water quality at Lake Natoma and Folsom Reservoir when 

loading, unloading, and transporting materials to be used for the Folsom 
Revised Draft- Subject to Change 5

DS/FDR project by taking appropriate measures to prevent soil, fuel, oil, 

lubricants, etc. from entering into these waters. 

o Minimize impacts to wildlife by using eco-friendly erosion control blankets that 

do not create wildlife entrapment issues. Using flexible joint netting or another 

erosion control alternative that doesn’t include monofilament fixed-joint netting 

would avoid entrapment issues that may occur with the fixed joint netting 

commonly used in erosion control blankets. 

o Minimize impacts to annual grassland habitat and other disturbed areas, by reseeding all disturbed areas with appropriate native grass species as construction 

elements are completed. 

o Minimize impacts to fish and phytoplankton during spillway construction 

(dredging and blasting) by implementing conservation and minimization 

measures (such as a curtain) during in-reservoir activities to minimize 

sedimentation and localize methylmercury dispersal.

o Compensate for unavoidable impacts to oak-grey pine woodland habitat by 

acquiring suitable lands and developing oak woodland habitat using the 

assumptions contained in Appendix A. Compensation acreages by project 

components are summarized in Appendix C. 

o Compensate for unavoidable impacts to riparian habitat by acquiring suitable 

lands and developing riparian habitat using the assumptions contained in 

Appendix A. Compensation acreages by project components are summarized in 

Appendix C. 

o Compensate for unavoidable impacts to seasonal wetland habitat by acquiring 

suitable lands and developing seasonal wetland habitat using the assumptions 

contained in Appendix A. Compensation acreages by project components are 

summarized in Appendix C. 

o Compensate for unavoidable impacts to chaparral habitat by acquiring suitable 

lands and developing the needed mitigation of chaparral habitat using the 

assumptions contained in Appendix A. Compensation acreages by project 

components are summarized in Appendix C. 

o Develop a monitoring and adaptive management program with the other 

agencies, to monitor vegetation around the reservoir over the life of the project. 

Baseline conditions would be established and updated at intervals (10 years). 

After major flood events (those which encroach above the existing maximum 

flood pool elevation), vegetation would be surveyed and damages attributable to 

inundation would be mitigated as deemed appropriate using best management 

practices at the time (replanting on-site would be the first priority). Budget in 

advance for this monitoring and adaptive management program. 
Revised Draft- Subject to Change 6

o Develop a monitoring and adaptive management plan with the other agencies, to 

monitor the hydrology and vegetation at Mormon Island Preserve. Baseline 

conditions would be established before construction begins in the area and 

would continue for 4 years after construction has been completed. Postconstruction surveys would monitor for potential changes in wetland hydrology, 

water quality, and vegetation. If changes in wetland hydrologic function are 

detected from the baseline condition, implement adaptive management 

mitigation to return affected systems to baseline conditions considering the 

long-term conservation of the Mormon Island Preserve. 

o Develop operation and maintenance manuals (O&M Manual) for all mitigation 

sites developed for the project. Coordinate with the Service on the development 

of the all O&M Manuals. 

o Monitor methylmercury levels in water and suspended sediment of water being 

released from Folsom Dam during in-reservoir construction activities until 

levels return to baseline. 

o Complete a more thorough assessment of freshwater sediment effect levels for 

contaminants of concern, in particular mercury and nickel. Many of the 

references used in Reclamations’ Sediment Characterization document to 

identify effect levels were inappropriate for fish and wildlife assessment needs. 

Other references such as MacDonald et al. (2000) and EPA (2004) provide good 

assessment guidelines for freshwater sediment. 
Revised Draft- Subject to Change 7

INTRODUCTION 

The U.S. Army Corps of Engineers (Corps) and the U.S. Bureau of Reclamation (Reclamation) 

seek to significantly reduce the risk of flooding along the main stem of the American River in the 

Sacramento area while meeting dam safety and public safety objectives. 

This report provides: (1) the U.S. Fish and Wildlife Service's (Service) analysis of impacts to 

fish and wildlife that would result from construction and operation of the various Folsom Dam 

Safety and Flood Damage Reduction (Folsom DS/FDR) project alternatives; (2) 

recommendations to avoid, minimize, rectify or, as a last resort, compensate these impacts; and 

(3) the Service's assessment of project alternatives based on a fish and wildlife conservation 

perspective. The analysis herein is based on the February/March 2007, project description 

provided by the Reclamation and Corps as well as site visits, literature review, discussions with 

experts, and a revised project footprint provided January 2007. 

The current study was implemented under several existing authorizations. The Corps project 

authorities are the: Folsom Dam Modification, authorized under section 101(a) (6) of the Water 

Resources Development Act (WRDA) of 1999 (Public Law (PL) 106-53) and the Folsom Dam 

Raise, authorized in the Energy and Water Resources Development Act of 2004, dated 

December 1, 2003 (PL 108-137) both of which are to enhance flood protection. Reclamation has 

also been pursing dam safety risk reduction improvements separately through its existing Dam 

Safety Program. Investigations by Reclamation have identified dam safety risk reduction needs 

at Folsom Dam and appurtenant facilities. Reclamation has commenced a Corrective Action 

Study (CAS) to identify possible, probable, and preferable design modification alternatives to 

address identified risk reduction needs for submittal to Congress for approval. 

However, recent modifications to the existing authorities were made in the Energy and Water 

Appropriations Act of 2006, which directed the Secretary of the Army and the Secretary of the 

Interior to collaborate on authorized activities to maximize enhanced flood protection 

improvements and address dam safety risk reduction needs at Folsom Dam and Reservoir as one 

Joint Federal Project. The text of this most recent authorization follows: 

SEC. 128. American River Watershed, California (Folsom Dam and Permanent Bridge) 

(a) COORDINATION OF FLOOD DAMAGE REDUCTION AND DAM SAFETYThe Secretary of the Army and the Secretary of the Interior are directed to 

collaborate on authorized activities to maximize flood damage reduction 

improvements and address dam safety needs at Folsom Dam and Reservoir, 

California. The Secretaries shall expedite technical reviews for flood damage 

reduction and dam safety improvements. In developing improvements under this 
Revised Draft- Subject to Change 8

section, the Secretaries shall consider reasonable modifications to existing 

authorized activities, including a potential auxiliary spillway. In conducting 

such activities, the Secretaries are authorized to expend funds for coordinated 

technical review and joint planning, and preliminary design activities. 

Both Reclamation and the Corps have conducted engineering studies to identify potential 

corrective measures for the Folsom Facility to alleviate seismic, static, and hydrologic dam 

safety issues, and flood management concerns. These two Federal agencies have combined their 

efforts resulting in (1) a Joint Federal Project for addressing Reclamation’s dam safety 

hydrologic risk and the Corps’ flood damage reduction objectives and (2) other stand-alone flood 

damage reduction and dam safety actions to be completed by the respective agencies in a 

coordinated manner. 

DESCRIPTION OF THE PROJECT AREA 

The Folsom Facility is located about 23 miles northeast of Sacramento, near the City of Folsom, 

California. The Folsom Facility impounds waters from the North and South Forks of the 

American River and was constructed to provide flood damage reduction, water supply and 

hydropower. The Folsom DS/FDR project is located around Folsom Reservoir which is within 

Sacramento, Placer and El Dorado counties (Figure 1). Figure 2 shows several of the project 

components in relation to the Folsom Reservoir. The Folsom Facility is made up of 12 dams and 

dikes that impound about 977,000 acre-feet at a reservoir water surface elevation of 466 feet. 

The Folsom DS/FDR project includes measures to remedy dam safety issues associated with 

seismic, static, and hydrologic concerns, and to provide increased flood damage protection. 

These measures include several different options to remedy the various issues at the Folsom 

Facilities. The Folsom Facilities to be addressed by one or more of the engineering options 

include the main concrete dam, the right wing dam and left wing dam, Mormon Island Auxiliary 

Dam (MIAD), and eight dikes (1 through 8). The concrete dam and earthen wing dams serve to 

impound water associated with the main stem of the American River. MIAD was built within an 

historic river channel, while the earthen dikes serve to contain water at low spots in the 

topography during periods when the reservoir is full or nearly full. 

DESCRIPTION OF THE PROJECT ALTERNATIVES 

NO ACTION ALTERNATIVE 

The No Action/No Project Alternative describes the reasonably foreseeable future without the 

Folsom DS/FDR project. Without the project the hydrologic, seismic, static, and flood damage 

risks currently posed by the Folsom Facilities would continue into the future. 
!.

!.

!.

!.

!.

0 1 2 0.5 Miles



January 30, 2007 S. Rickabaugh; USFWS- Sacramento Fish and Willdifie Office

Figure 2- Project Location

Borrow and Stockpile Sites

Haul Routes

Dike Construction Zones

Dikes 1-3

Contractor/Construction Areas

!. Processing Plant Locations

Folsom Lake

N. Fork

S. Fork

Prepared by the US Fish and Wildlife Service, Sacramento Fish and Wildlife Office, Flood and Waterway Planning Branch; February 27, 2007

This map is for illustrative purposed only. The US Fish and Wildlife Service shall not be held liable for improper or incorrect use of the data described and/or contained hereein.

10
Revised Draft- Subject to Change 11

Action Alternatives 

In addition to the No Action/No project Alternative, the Folsom DS/FDR project evaluates five 

action alternatives. The basic features of the five alternatives are outlined below. 

CONSTRUCTION ALTERNATIVES 

1. Auxiliary Spillway 

The auxiliary spillway would consist of an approach channel on the water side of the control 

structure, a control structure section consisting of either a segmented earthen fuseplug control 

structure or a four-or six-submerged tainter gate control structure, and a discharge chute on the 

downstream side of the control structure. The spillway would convey the reservoir discharge to 

the American River channel without impact to the left wing dam. The discharge chute linings 

would be either a short lined-chute, constructed in the upper portion of the spillway, or a fullylined chute constructed completely to the river discharge point. The spillway chute would be 

lined either with roller compacted concrete, or structural, formed, and poured concrete. The 

auxiliary spillway would be constructed by excavating an elongated trench in the area adjacent to 

and downstream of the left wing dam, diagonal from the current overlook parking lot. The 

excavation of the approach and discharge channels would be done in three stages. The first stage 

would include removing common material and some excavation of the rock. The underlying 

competent bedrock would be excavated using standard drill and blast techniques. The second 

stage would involve additional excavation and possibly the construction of a rock plug. A rock 

plug and/or coffer dam would be used to close off the partially excavated approach channel. The 

third stage would involve excavating the approach and discharge channel to the final grade as the 

auxiliary spillway is being completed. In-reservoir material would be removed by a clamshell 

dredge, although some material would have to be removed through blasting as the primary 

means of excavation. The spillway would be controlled by either an earthen fuseplug control 

section that would meet the dam safety objectives of passing the probable maximum flood 

(PMF) or submerged tainter gates that would meet both dam safety and flood control objectives. 

Features of the fuseplug spillway and tainter gate spillway are provided in the following sections. 

A. Fuseplug Spillway 

A control structure with fuseplug embankment sections could serve on a permanent basis. The 

spillway would be excavated and constructed as described above, however the fuseplug section 

would consist of a zoned embankment with an impervious core, an internal coarse shell zone, 

and erosion protection on the upstream face. The fuseplug embankment sections would be 

designed to erode in a controlled manner when the reservoir elevation exceeds the elevation of a 

pilot channel (by about 1 foot) and would be 2 feet below the fuseplug embankment crest. The 

fuseplug spillway would have a 520-foot-wide control structure at the upstream end of a 

1,100-foot-long, 300- to 520-foot-wide roller-compacted concrete-lined channel. This channel 

would lead to a 1,700-foot unlined channel discharging into the American River. The fuseplug 

control structure would be designed with multiple segments to allow progressive passage of 

smaller floods up to the PMF flow without affecting the complete fuseplug control structure. 
Revised Draft- Subject to Change 12

The fuseplug alternatives would require placement of material in the reservoir at the Folsom 

Lake Observation Point on the left wing dam to increase the efficiency of the auxiliary spillway. 

B. Gated Spillway 

Another option for the auxiliary spillway control section would be the use of mechanical gate 

(submerged tainter gates) housed in a concrete structure to meet both dam safety and flood 

damage reduction objectives. A gated spillway would take longer to construct and would 

involve three construction phases. Construction of the spillway would be in phases by 

excavating an elongated trench in the area adjacent to and downstream of the left wing dam to a 

profile to safely pass the PMF. The gated auxiliary spillway would consist of an approach 

channel on the waterside of the gate, a control structure consisting of four or six submerged 

tainter gates, and a concrete-line chute leading to an energy dissipating structure and exit 

channel. The discharge chute would be fully lined with formed concrete and is inclusive of an 

energy-dissipating unit (stilling basin) at the river. The gated spillway would have a 190-footwide control structure at the head of a 1,700-foot-long channel and would have a discharge 

capacity of about 280,000 cubic feet per second (cfs) at pool elevation 477 feet. The gated 

sections would be designed to allow safe passage of more frequent, smaller flood events and 

maintain the capability to safely pass the PMF without overtopping the other retention structures. 

2. New Stilling Basin 

A new stilling basin would need to be constructed at the end of the new gated auxiliary spillway 

to dissipate the hydraulic energy during water releases and keep water released from the dam 

from backing up into the new spillway. Construction would include a temporary concrete coffer 

dam in the main channel to redirect releases coming from the dam. The coffer dam would 

remain until the spillway and new stilling basin are constructed. This component of the project 

is still in the design phase so subsequent environmental documentation will be prepared.

3. Existing Spillway 

The existing stilling basin was designed so that it could contain hydraulic jump action for flows 

up to 200,000 cfs and prevent major damage during the existing spillway design flood event. 

Flows above 200,000 cfs would result in hydraulic jump farther downstream. Because releases 

from the main dam with an auxiliary spillway could be increased from the current 567,000 cfs 

maximum to 920,000 cfs with this project, an increase in spillway design flood capacity is 

warranted. To address this concern, the existing stilling basin would be extended 50 to 70 feet 

downstream. 

A. Gate Improvements 

Minor to moderate modifications are being considered to reduce seismic risks. These 

modifications range from reinforcing the existing gate wings to replacing the existing gate arms. 
Revised Draft- Subject to Change 13

B. Gate Replacement 

The existing concrete dam service and/or emergency spillway gates are proposed for replacement 

under a dam raise option because structural members for the existing gates would be impacted 

during passage of large flood releases. The proposed gates would be higher, and the new trunion 

would be outside of the stream flow for large flood releases. As a consequence of gate 

replacement, the existing spillway bridge would also need to be replaced. 

C. Spillway Pier Reinforcements 

To reduce seismic risks, spillway pier reinforcements may be comprised of bracing, post 

tensioned anchors, and/or pier wraps. 

4. Main Dam Seismic Improvement 

The main dam was constructed of concrete monoliths that may have the potential to slide on 

horizontal lift lines within the dam during a large earthquake event. Engineering options being 

considered to reduce the probability of main dam movement include upper and lower tendons, 

shear keys, and toe-blocks. 

5. Filters 

To better control seepage and piping (movement of water through the core that carries soil 

material) on the existing earthen structures (wing dams, dikes and MIAD), sand filters are 

proposed to be constructed within the downstream part of the earthen structures. Two 

alternative types of filters for dikes are being considered for the downstream face. The fullheight filter would extend upward from the downstream toe of the dike to the crest of the dike. 

The half-height filter would extend from the downstream toe to half the vertical distance to 

elevation 466 feet. Additionally, on the left and right wing dams, crest filters in the upper 

portion of the dam and area where the soil and concrete adjoin is also being evaluated. Due to 

concerns about piping along the embankment interface with the concrete dam, filter zones are 

required along these contacts. This would be constructed by excavating a portion of the outer 

zones of the left wing dam and right wing dam so that filter material could be placed against the 

core materials of these dams. The filter zones would provide protection against both static and 

seismic loading conditions. 

At the left and right wing dams, filter zones are required only in the upper portion of the dams. 

Sand filter zones would be constructed from the crest to an elevation about 40 feet below the 

dam crest. This filter zone would be constructed by excavating a 40-foot portion of the 

downstream shell and placing the filter material against the core. The filter zone would then be 

covered by a layer of excavated shell material. This filter zone would exit into the downstream 

face of the embankment. Construction zones at the dikes and wing dams varies to minimize 

habitat impacts, however, in general they range from 50 to 100 feet from the existing toe.
Revised Draft- Subject to Change 14

6. MIAD Jet Grouting and Seismic Alternatives 

Part of MIAD is constructed over an historic river channel, Blue Ravine. This portion of the 

dam, towards the left end of the dam, is at risk of significant deformations should the foundation 

of the dam liquefy during a severe earthquake event. Two design alternatives are being 

considered to prevent these deformations from occurring. These alternatives are jet grouting the 

lower zones of liquefiable material in the downstream foundation material and increasing the 

size of the downstream side of MIAD by adding additional material. 

Jet grouting would be used to stabilize the foundation of MIAD. Soil borings would be drilled 

using special drilling equipment and would be drilled through the potentially unstable dredged 

alluvial or historic alluvial material and then into the underlying bedrock. Once the desired 

depth is achieved, a concrete-based grout would be injected and extruded into the subsurface 

using jets along the side of the drill pipe. The grout would be injected under high pressure into 

the formation, filling voids. Exploratory borings would be drilled into the grout columns to 

verify the extent that voids are filled and the grout has set and hardened. The exploratory 

borings would be backfilled with concrete. 

Approximately 1,360 borings would be drilled for jet grouting purposes. Within each boring, 

about 26 tons of grout would be injected. During grouting, drilling cuttings, water, and grout 

would be brought to the surface. This waste material would be directed to temporary, lined 

settling pits for solidification, removal, and disposal. Up to 70 cubic yards of waste material 

would be generated at each bore hole. This material would be dried and stockpiled on site. 

Eventually the dried material would be incorporated into the downstream overlay of MIAD 

pending review and approval by the Regional Water Quality Control Board. 

The second construction activity for MIAD would be increasing the mass of MIAD by placing 

an overlay on the downstream side. Although the upstream toe of MIAD was treated with 

dynamic compaction in the 1990s, the lower portion of MIAD was too deep to have been 

effectively treated by that procedure. Therefore, there still is some risk for large sliding or 

deformation to occur due to upstream liquefaction. Because the presence of the reservoir makes 

it difficult to treat the upstream toe, the project would involve excavation of a portion of the 

downstream fill, placement of a filter layer, replacement of shell, and then placement of an 

overlay of up to 2 million cubic yards. The downstream overlay would not prevent upstream 

sliding and deformation, but it would reinforce MIAD with adequate mass to withstand a seismic 

event. The overlay would also incorporate the installation of a filter zone. Installation of the 

overlay could result in raising the height of MIAD up to 4 feet. The purpose of the overlay 

would be strictly for seismic and static concerns, and would not necessarily provide additional 

hydrologic control (temporarily increase flood storage), unless all other Folsom Facilities were 

also raised. 

7. Borrow, Stockpile and Disposal Sites 

Borrow sites would be on Federal property within and immediately outside of the reservoir. The 

number and extent of borrow site development would be dependent on the amount of earthen 

material required to accomplish the various project components. Potential borrow sites include: 
Revised Draft- Subject to Change 15

along the low water shoreline opposite Beals Point Recreation Area and to the north along 

Mooney Ridge and Granite Bay; excavation material from the auxiliary spillway and/or tunnel; 

MIAD right abutment (Folsom Point), MIAD left abutment, D1 site, and D2 site. Borrow sites 

would also be used for stockpiling of material. However; depending on the alternative chosen 

excess material maybe permanently disposed of at Dike 7, Beals Point, Folsom Point, D1 and 

D2, Overlook parking lot, Hobie Cove, Granite Bay or MIAD as additional overlay. 

8. Staging Areas and Haul Roads 

There would be three primary staging areas: left wing dam/Overlook Point, D2, and on a 

constructed platform south of Beals Point; as well as several secondary staging sites set up at or 

immediately adjacent to the toes of Dikes 4, 5, and 6, and the right wing dam. This would 

include contractor’s offices, parking, and staging of materials. Other potential staging areas 

include Beals Point and Dike 4 for screening and staging, Granite Bay and D1/D2 for both 

processing and staging, and MIAD for a jet grout plant and a staging area. 

The main dam overlook parking lot staging area would include contractor offices and parking, 

materials storage, and a concrete mixing plant. This would be the longest occupied staging area 

given that the dam seismic work would be scheduled last. 

Hauling of equipment, materials and supplies from the west to east side construction sites would 

be conducted on city streets or internal haul roads. Typical materials to be hauled on city streets 

include concrete, reinforcement steel, general supplies and if needed, aggregate and sand. 

The internal haul roads would be developed to reduce construction traffic on city streets and to 

allow the use of oversized construction equipment. The internal haul roads would be graded into 

the weathered granite and have an earthen road base installed or use cut and fill techniques to 

establish the 40 foot-wide road to allow passage of oversized equipment. Internal haul roads 

include those constructed in-reservoir as well as the crests of the dikes, wing dams, MIAD and 

Folsom Dam Road. Given the space limitations of the crests, only conventional sized equipment 

would use the dikes, wing dams or MIAD. 

9. Security Upgrades 

To provide the required level of security for the dam the following would be installed: access 

controls, intrusion detection, supplemental lighting and closed circuit television throughout the 

power plant, pump plant, elevator tower, industrial area, administration area, recreational areas, 

Dikes 4-7, MIAD, the wing dams, Folsom Dam itself and Folsom Dam Road. 

10. Exploratory Work 

A certain amount of exploratory geologic and geotechnical work has occurred to better 

characterize the subsurface conditions within the proposed auxiliary spillway location and 

around MIAD. 
Revised Draft- Subject to Change 16

The Corps exploration program for the auxiliary spillway consisted of drilling about 20 rock core 

borings and conducting down-hole seismic surveys, optical televiewer logging, and in-situ 

testing within the proposed footprint of the auxiliary spillway and it appurtenances, with a future 

option of 10 additional borings. This exploratory work required initial earthwork to construct 

drill pads and access roads to the drill sites. 

 

Reclamation also has an exploration program for the auxiliary spillway, which included drilling 

six core holes. 

 

11. Processing Plants 

Five material processing plants would be needed for filtering material and for concrete 

preparation. Plants would be located at MIAD, Folsom Point/Dike 8, Beals Point, Granite Bay 

and Mooney Ridge areas. Reclamation anticipates most of the material for filters (sand and 

gravel) would come from local off-site suppliers, so screening plants may only be needed in 

some instances. 

12. New Embankment Raises 

All earthen structures could be raised through the placement of additional earthen material, 

construction of concrete parapet walls, or a combination of the two measures, along the crest of 

the facilities. The purpose of the minimal embankment raises, as in Alternatives 1 and 2, would 

be to provide additional (up to 3 feet) freeboard to the existing facilities for dam safety concerns. 

Higher raise options could serve to provide additional flood damage reduction storage capacity 

during low frequency storm events. However, a raise is intended to provide additional freeboard 

to all impoundment facilities, not to increase reservoir water elevation above current operation 

Several options exist for the raising of existing dikes and wing dams. Embankment raise options 

are conventional earth fill raise, reinforced earth wall raise, reinforced concrete retaining wall 

raise, and combination earthen raise and concrete wall raise. The raise component will undergo 

further design during the Corps’ preconstruction engineering and design phase, and if needed 

supplemental environmental coordination and documentation would be prepared. 

Work at Dikes 1 thru 3 is considered part of the raise component, therefore, in this document a 

construction buffer of 50 feet from the dike toe has been included for evaluating habitat impacts 

that would occur from any embankment raise at these three dikes. Raise activities at other 

locations would be within the existing footprint 

Any of the alternatives involving a raise of Folsom Facility structures could result in a temporary 

increase in the reservoir water elevation during periods of maximum flood flows into the 

reservoir. This increase in the reservoir water elevation could result in the potential to flood 

property beyond the boundaries of Folsom Reservoir at locations with lower land elevations. 

However once completed, the auxiliary spillway would have the ability to increase the reservoir 

discharge capacity at a lower pool elevation with no increase in pool elevation. This allows a 

lowering of the maximum pool and a decrease in the need for use of surcharge storage space in 

the reservoir. However, a Folsom Dam Re-operations study will be completed prior to any 

releases from the newly constructed auxiliary spillway. Therefore, the need for easements, new 
Revised Draft- Subject to Change 17

embankments or other containment alternative will continue to be analyzed by the Corps. The 

Corps will continue to analyze the project hydrology and the need for a raise, essentially 

creating additional freeboard space in the reservoir. The Corps will issue its findings in a 

subsequent environmental document, if necessary.

Action Alternatives 

Alternative 1– No Dam Raise/Minimal Embankment Raise/Fusplug Auxiliary Spillway 

Under Alternative 1, there would be no raise to the concrete structure with minimal 

modifications to the existing spillway. A large auxiliary spillway would be constructed adjacent 

to the left wing dam to address hydrologic and flood control concerns. Some of the earthen 

structures would be raised to address hydrologic concerns, but not to increase the flood storage 

capacity of the reservoir since this alternative is a Dam Safety only alternative. 

Alternative 2– Four-Foot Dam/Embankment Raise/Fuseplug Auxiliary Spillway with 

Tunnel

Alternative 2 incorporates a 4-foot dam raise with a fuseplug auxiliary spillway and gatecontrolled tunnel spillway for better hydrologic control of large flood events. Under this 

alternative, there would be a 4-foot raise to the concrete structure with some modifications to the 

existing spillway gates. An auxiliary spillway with a chute or a tunnel would be constructed to 

address hydrologic and flood control concerns. All of the earthen structures would be raised to 

address hydrologic concerns and to provide additional flood storage capacity. 

Preferred Alternative, Alternative 3 – Six-Submerged Tainter Gate Spillway/3.5-Ft Raise 

Under the Preferred Alternative a smaller six-submerged tainter gate (six gate) auxiliary spillway 

would be constructed to address both Dam Safety and Flood Damage Reduction objectives 

including hydrologic and flood control concerns. Construction of the six gate auxiliary spillway 

would increase project discharge capacity. The 3.5-foot raise, in conjunction with modification 

and/or replacement of the three emergency spillway gates and the six-gate auxiliary spillway, 

would only serve as additional freeboard for the Folsom Facilities. Once construction is 

completed the raise would not exceed the existing take line for a 200-year design event and there 

would be an anticipated lower maximum water surface elevation. The 3.5-foot raise, 

modification and/or replacement of the three emergency spillway gates and the six-gate auxiliary 

spillway, have been identified by the Corps as their Selected Plan within the Corps’ Post 

Authorization Change report. The remaining elements of Alternative 3 are Dam Safety 

Modification as revised above. 

Alternative 4– Seven-Foot Dam/Embankment Raise/Four-Submerged Tainter Gate 

Spillway 

Alternative 4 contains many of the same elements as Alternative 3 with the exception of a 7-foot 

raise that could result in increased reservoir flood storage during large flood events. Under this 
Revised Draft- Subject to Change 18

alternative all Folsom Facilities and earthen structures would be raised 7 feet. A smaller foursubmerged tainter gate (four gate) auxiliary spillway would be constructed to address hydrologic 

and flood control concerns. 

Alternative 5– Seventeen-Foot Dam/Embankment Raise/No Spillway 

Alternative 5 was specifically developed as an alternative that would address both Dam Safety 

and Flood Damage Reduction requirements without the construction of an auxiliary spillway. 

Under this alternative all Folsom Facilities could be raised 17 feet which would increase 

reservoir storage capacity to control large flood events. 

BIOLOGICAL RESOURCES 

EXISTING CONDITIONS 

Existing conditions are those conditions which exist in the project area at the time of the impact 

analysis. 

FOLSOM DAM ENLARGEMENT

Vegetation

Around Folsom Reservoir and Upstream 

The area surrounding Folsom Reservoir supports a mix of habitat types, dominated by blue oakgrey pine woodland. The lower foothill area near Folsom Dam contains large areas of oak 

woodland, with scattered blue oaks and interior live oaks. Small areas of chaparral extend to the 

reservoir's upper edge particularly along the South Fork arm. Annual grassland areas are 

interspersed throughout the area, and human-disturbed habitats occur around boat-launch 

facilities. Relatively small areas of riparian habitats can be found along tributaries to the 

reservoir and in seep areas. Willow stands and individual trees have become established within 

some areas of the reservoir pool. 

MIAD serves to dam water within an historic river channel thus creating several perennial 

wetlands on the landside in addition to a wetland preserve (Mormon Island Preserve) run by 

California Department of Parks and Recreation on the east side of Green Valley Road. No 

studies have been completed to date that definitively show where the water for these wetlands 

originates. It is possible that during wet weather the hills to the east funnel the runoff into the 

Preserve and, using the old riverbed, water travels into the remaining wetland across the Green 

Valley Road. Another possibility is that water seeps from MIAD into the wetland and the 

Preserve. Any construction in and around MIAD may have direct impacts to these wetlands and 

will need to be monitored during and after construction of the Folsom DS/FDR project. The 

wetland acreage within Mormon Island Preserve has not been included in this impact analysis. 
Revised Draft- Subject to Change 19

Lower American River

The lower American River, although highly modified from conditions of 150 years ago, supports 

a diverse and highly valuable area for biological resources. The 23-mile-long reach of the 

American River Parkway encompasses about 4,000 acres, the majority of which are in State 

designated floodway and contain large areas of grasslands and pasture, riparian cottonwood and 

oak woodlands, herbaceous plants and riparian scrub-shrub, bare sand and gravel, and surface 

waters of the river and associated sloughs and dredge ponds (USFWS 2003). Most of the area is 

high floodplain dominated by upland species, including oak woodland and grasslands (per. com. 

T. Burwell). 

Fish

Folsom Reservoir and Upstream

When full (i.e., around 1 million ac-ft), Folsom Reservoir encompasses about 10,000 surface 

acres of water and 75 miles of shoreline, extending about 15 miles up the North Fork and 10.5 

miles up the South Fork of the American River. It supports a “two-stage” fishery: warmwater 

species such as bass (largemouth, smallmouth, and spotted) and panfish (crappie, bluegill, and 

sunfish) in the upper waters, and trout and landlocked salmon (kokanee and Chinook) in the 

deeper waters. Various common catfish can also be found near the bottom of shallower waters. 

Fish habitat is present within the inundation zone in the forms of young willow dominated 

riparian habitat which grows during extended periods of drought, as well as brush piles placed 

there by the California Department of Fish and Game (CDFG) and sportsmen groups. Both 

warmwater and coldwater fisheries tend to benefit from increased peak spring water storage as 

this results in better coldwater reserves for the salmonid fishes as well as increased spawning and 

rearing area for warmwater fish (USFWS 2001). Sport fishing is an important and popular 

recreational activity at Folsom Reservoir. 

Sediment associated with the Folsom DS/FDR project area in the Folsom Reservoir may contain 

mercury from historic mining operations and metals from historic activities or geology in the 

American River drainage (Reclamation 2006a). Most of the mercury in water, soil, sediments, or 

plants and animals is in the form of inorganic mercury salts and organic forms of mercury (e.g., 

methylmercury). Mercury cycles in the environment as a result of natural and human activities 

and can accumulate most efficiently in the aquatic food web. Predatory species at the top of the 

food web generally have higher mercury concentrations. Nearly all of the mercury that 

accumulates in fish tissue is methylmercury (EPA 2006). 

Lower American River 

The lower American River supports a diverse and abundant fish community; altogether, at least 

41 species of fish are known to inhabit the river (USFWS 1986). In recognition of its 

"outstanding and remarkable" fishery resources, the entire lower American River was included in 

the Wild and Scenic Rivers System in 1981, which provides some protection for these resources 

(USFWS 1991). Four anadromous species are important from a commercial and recreational 

perspective. The lower river supports a large run of fall-run Chinook salmon, a species with both 

commercial and recreational values. The salmon run is sustained by natural reproduction in the 

river, and by hatchery production at the Nimbus Salmon and Steelhead Hatchery, operated by 

CDFG. The average annual run of salmon in the American River is 25,948 (CDFG 2006). 
Revised Draft- Subject to Change 20

Steelhead, a popular sport fish, are largely sustained in the river by production from the Nimbus 

Hatchery, because summer water temperatures often exceed the tolerances of juvenile steelhead, 

which typically spend about 1 year in the river. American shad and striped bass enter the river to 

spawn; these two species, introduced into the Sacramento River system in the late 1800s, now 

support popular sport fisheries. In addition to species of economic interest, the lower American 

River supports many nongame species, including Sacramento pikeminnow, Sacramento sucker, 

tule perch, and hardhead (USFWS 1994). 

Wildlife

 

Around Folsom Reservoir and Upstream

The area around Folsom Reservoir supports an animal community characteristic of the lower 

Sierra Nevada western slope. Although the range of elevation is small, habitats are diverse, in 

part because the reservoir extends about 20 miles into the Sierra Nevada foothills, from gentle 

hills near the dam to steep-walled canyons along the forks of the American River. More than 50 

species of mammals live in these areas (USFWS 1986). Common species include mule deer, 

striped skunk, black-tailed jackrabbit, brush rabbit, raccoon, California ground squirrel, and a 

diverse assemblage of small mammals including mice, voles, and pocket gophers. Less common 

mammals include river otters, mountain lions, badgers and bobcats. Birds typical of oakdominated habitats include acorn woodpeckers, scrub jays, ash-throated flycatchers, and 

California quail. Oaks provide acorns, a nutrient-rich and important food source for mule deer, 

acorn woodpecker, northern flicker, Nuttall's woodpecker, white-breasted nuthatch, and scrub 

jay. In addition to a diverse community of small passerine birds, other birds such as 

woodpeckers, California quail, introduced wild turkeys, Canada geese, and various birds of prey 

are fairly common near the reservoir. 

The presence of year-round water provides habitat for many water-associated species such as 

raccoon, wood duck, common merganser, mallard, black phoebe, great blue heron, greater 

yellowlegs, belted kingfisher, and common yellowthroat. The Mormon Island Preserve also 

provides a perennial wetland for many species including pond turtles. 

Mammals likely found in the study area include California vole, ringtail, black-tailed jackrabbit, 

coyote, striped skunk, and mule deer; the typical mix of species found in riparian and woodland 

habitats with a herbaceous understory. 

Reptile and amphibian species likely found in the study area include western fence lizard, gopher 

snake, western rattlesnake, common kingsnake, Pacific treefrog, and western toad. 

Wildlife species that forage or breed in oak woodlands also include dusky-footed woodrat, 

western bluebird, and southern alligator lizard. 

Areas dominated by annual grassland provide foraging habitat and cover for California ground 

squirrel, pocket gopher, turkey vulture, coyote, western fence lizard, western rattlesnake, western 

kingbird, and western meadowlark. Grassland areas are important to many foraging raptors; redtailed hawk, golden eagle, ferruginous hawk, rough-legged hawk, American kestrel, and prairie 

falcon all spend time in the area, as wintering and/or breeding birds. 
Revised Draft- Subject to Change 21

Lower American River

The lower American River corridor provides a mosaic of riparian, riverine, grassland, and oak 

woodland habitat. These diverse habitats support a corresponding diversity of wildlife. 

The lower American River provides feeding, resting, and/or nesting habitat for many bird 

species, many of which require the aquatic areas of the river and backwaters, or the riparian 

vegetation of the ecosystem. Riparian areas are known to support a species-rich songbird 

community (Gaines 1977), and the lower American River also provides habitat for many raptors, 

including Swainson's hawks, red-shouldered hawks, Cooper's hawks, and great-horned owls, all 

of which require or are closely associated with riparian vegetation. Bald eagles, which are more 

common around Folsom Reservoir, occasionally use the lower river, which provides roosting and 

foraging habitat. Waterfowl, particularly mallards and Canada geese, also use the area 

extensively. 

More than 50 species of mammals have been recorded for the area (USFWS 1986). Common 

species include beaver, black-tailed jackrabbit, striped skunk, Virginia opossum, raccoon, 

California ground squirrel, gophers, and many small rodents and insectivores including voles, 

moles, shrews, deer mice, and pocket gophers. Uncommon species include mule deer, and 

several carnivores, such as badger, long-tailed weasel, river otter, gray fox, coyote, bobcat, and 

mink. 

Reptile species of the lower American include common kingsnake, Gilbert and western skinks, 

southern alligator lizard, western fence lizard, gopher snake, and several garter snakes. Common 

amphibians include Pacific treefrog, California newt, California slender salamander, western 

toad, and the introduced bullfrog. 

Relatively little is known about invertebrates of the lower American River, but elderberry plants 

are fairly common in areas, and provide habitat for the endangered valley elderberry longhorn 

beetle. 

FUTURE CONDITIONS WITHOUT THE PROJECT 

Future without-project conditions are those conditions expected to occur over the life of the 

project if the project were not implemented. 

Vegetation

Around Folsom Reservoir and Upstream

Without-project conditions for this project area are not expected to change significantly from the 

baseline condition over the life of the project. Refer to the baseline condition described under 

the no action alternative. 
Revised Draft- Subject to Change 22

Lower American River

Under without-project conditions, vegetation in and along the lower American River would 

continue to undergo changes typically associated with a riparian system, but constrained and 

limited by the adjacent levee system, upstream dams, and regulated flow releases. Regeneration 

of riparian species, particularly cottonwood and willows, will slowly decline, as continued lateral 

erosion, net downstream sediment movement, and increased amount of higher terrace areas, 

exposed to less frequent flooding, develop as a result of increased channel stability. These 

processes have resulted from the construction of Folsom Dam and channel modifications along 

the lower American River (USFWS 1991). 

Sediment deposition needed for the establishment of these riparian species will continue to be 

limited by upstream impoundments. Forest complexes would be dominated by species adapted 

to relatively low water needs. Riparian species will gradually mature then die out, giving way to 

more drought-tolerant plant species such as ash, box elder, and valley and live oaks. Vegetation 

will continue to be affected by its location in a major metropolitan area. Associated impacts 

include vandalism, burning, and mowing for firebreaks, among the more common human 

disturbances. Some younger riparian vegetation that exists under baseline conditions will 

continue to develop over time into mature riparian woodland habitat. Habitat abundance and 

diversity is not expected to change significantly over time in the hydraulic mitigation areas. 

Fish

Around Folsom Reservoir and Upstream

Without-project conditions for this project area are not expected to change significantly from the 

baseline condition over the life of the project. Refer to the baseline condition described under 

the no action alternative. 

Lower American River

Conditions for fish in the lower American River are likely to change in the future without the 

project. However, the way in which it will change is difficult to predict. With continued 

implementation of the Anadromous Fish Restoration Program (AFRP) of the Central Valley 

Project Improvement Act (USFWS 1995), conditions in the lower American River are expected 

to improve for fishery resources. 

Other variables will determine the way in which flows are managed on the lower American 

River; including meeting the needs of Bay-Delta water quality standards, Reclamation’s existing 

and renewed water contracts, and any additional new water contract quantities. 

Wildlife

Around Folsom Reservoir and Upstream

Without-project conditions for this project area are not expected to change significantly from the 

baseline condition over the life of the project. Refer to the baseline condition described under 

the no action alternative. 
Revised Draft- Subject to Change 23

Lower American River

The types of wildlife species found in the area would likely change somewhat along the lower 

American River under without project conditions, due primarily to the changes in vegetation 

described above and overall habitat abundance and diversity. Species which would decrease in 

number are those that prefer tree species such as cottonwood and willow for perching, foraging, 

and/or nesting (USFWS 1991a), as these plant species would likely decrease over time. Such 

wildlife species include birds such as woodpeckers, flickers, wrens, and raptors, and other avian 

species that use these riparian areas to meet their life requirements. Alternatively, species that 

prefer more arid habitats, such as oak woodland, would increase over time. 

FUTURE CONDITIONS WITH THE PROJECT 

Future with-project conditions are those conditions expected to occur over the life of the project 

if the project were implemented. 

CONSTRUCTION IMPACTS 

A. Folsom Reservoir 

Vegetation

Four cover-types: oak/grey pine woodland, riparian woodland, chaparral and seasonal wetland, 

would be directly impacted by construction of the Folsom DS/FDR project. The compensation 

acreage of Alternatives 1, 2, 4 and 5 are compared to that of Alternative 3, the Preferred 

Alternative, for these cover-types in Table 1. 

Table 1. Summary of Cover-Types, Acres Impacted, and Compensation Recommended by 

Alternatives Compared to the Preferred Alternative for the Construction of the Folsom 

DS/FDR Project, California. 

Folsom DS/FRD Project 

Alternative 3 (Preferred) 1 2 4 5 

Cover-Type Impacted Acres: 

Compensation 

Needed 

Difference from 

the Preferred 

Alternative 

Impacted Acres 

Difference from 

the Preferred 

Alternative 

Impacted Acres 

Difference from 

the Preferred 

Alternative 

Impacted Acres 

Difference from 

the Preferred 

Alternative 

Impacted Acres 

Oak/grey pine 

woodland 52.4 : 64.5 0.39 0.39 0.70 -1.07 

Riparian 

woodland 42.7 : 48.0 -0.28 -0.62 -0.15 -1.66 

Chaparral 0.7 : 0.8 0 0 0 -0.21 

Seasonal 

wetland 1.2 : 4.7 0 0 0 0 

Total 97.0 : 117.9 
Revised Draft- Subject to Change 24

A habitat assessment using Habitat Evaluation Procedures (HEP) was used to develop the 

compensatory mitigation acreage and is included in Appendix A. Based on the HEP, 

compensation ratios are: 1.2:1 oak/grey pine woodland; 1.1:1 riparian woodland; 

1:1 chaparral; and 4:1 seasonal wetland.

B) Auxiliary Spillway 

Three cover-types: oak/grey pine woodland, riparian woodland and chaparral would be directly 

impacted from the construction of the auxiliary spillway; a component of the Folsom DS/FDR 

project. The four spillway alternatives impact almost the same amount of acres in each of the 

cover-types (2.71 to 3.49 acres). Table 2 summarizes the cover-types impacted by the four 

spillway alternatives and their compensation needs based on the HEP results. 

Table 2. Summary of Cover-Types, Acres Impacted, and Compensation Recommended for the 

Construction of the Auxiliary Spillway Alternatives of the Folsom DS/FDR Project, 

California. 

Folsom Dam Auxiliary Spillway Alternatives 

 Six-gate Fuseplug Fuseplug with Four-gate 

 (Preferred) Tunnel

Alternative 3 1 2 4 

Cover Type Impacted 

Acres: 

Compensation 

Needed 

Impacted Acres: 

Compensation 

Needed 

Impacted Acres: 

Compensation 

Needed 

Impacted Acres: 

Compensation 

Needed 

Oak/Grey pine 

woodland 

1.07 : 1.38 1.46 : 1.89 1.46 : 1.89 1.77 : 2.29 

Riparian 

woodland 

1.66 : 1.88 1.38 : 1.57 1.04 : 1.18 1.51 : 1.71 

Chaparral 0.21 : 0.22 0.21 : 0.22 0.21 : 0.22 0.21 : 0.22 

Total 2.94 : 3.48 3.05 : 3.68 2.71 : 3.29 3.49 : 4.22 

The spillway site would be developed in three construction phases by excavating about 860,000 

cubic yards of material during the first phase, an additional 2.5 million cubic yards during the 

second phase and excavation of the approach channel would require removal of about 500,000 

cubic yards during the third phase. The material would be placed in haul trucks and taken to one 

of the staging areas. Some of the material may be utilized as riprap where needed. At the 

processing plant sites, the material would be screened and crushed to size required to reinforce 

MIAD (MIAD overlay), the wing dams, and Dikes 4, 5 & 6. Following processing, the material 

would be hauled to a given structure for immediate use, or the material could be stored either 

temporarily and/or permanently at Dike 8/Folsom Point, Dike 7, and near MIAD including D2. 

At Dike 7 and Dike 8/Folsom Point, excess excavation material may be placed permanently in 

the reservoir to create staging areas upstream of the structure. These areas would remain once 

construction is complete resulting in the loss of riparian woodland habitat. 
Revised Draft- Subject to Change 25

The third phase of construction of the spillway is the 900-foot-long waterside approach channel 

which would be constructed through dredging and blasting of materials. The approach channel 

invert and vertical sides would be concrete lined for about 50 feet upstream from the face of the 

control structure. The invert elevation for this concrete lining would be at the 368-foot sill 

elevation for the gates. Most of the approach channel would be excavated in rock to be resistant 

to erosion. Construction of the approach channel would require underwater blasting, dredging 

and excavating about 500,000 cubic yards of material. 

Permanent fill would need to be placed in-reservoir around the main dam observation point to 

increase the efficiency of the auxiliary spillway fuseplug alternative. 

C) Dike Zones, Borrow and Stockpile Sites 

For this analysis the earthen dike construction impacts include varying widths for the 

construction area from the landside toe of the dike: Dikes 4, 6, 7 and 8 assume 75 feet of impact 

from the toe; Dike 5 assumes 100 feet; Dikes 1-3, and right wing dam assumes 50 feet; MIAD 

and the left wing dam both have additional construction/staging impacts up to the toe. 

Impacts to seasonal wetlands from the construction and jet grouting to MIAD may occur from 

changes in water quality or the discontinued/muted flow of water from Folsom Reservoir 

into/out of the wetlands. 

D) Construction and Contractor Use Sites 

For this analysis all proposed construction and contractor use sites are the same for all the 

alternatives except below the left wing dam, where the proposed spillway would be located. 

Impacts to annual grassland would be minimized by seeding all disturbed areas with native 

grasses as soon as construction activities are complete in the disturbed area. It was anticipated 

that the work would be phased, so the entire annual grassland area would probably not be 

disturbed at the same time. Similarly, the impacts to other disturbed lands (these areas are roads, 

parking lots, riprap, etc, that do not currently provide significant values for fish and wildlife 

species) can be minimized by replanting with native annual grasses, when possible. 

E) Existing and New Stilling Basins 

The habitat impacts from the proposed extension of the existing stilling basin by 50 to 75 feet 

and the construction of a new stilling basin at the foot of the spillway has not been fully 

evaluated in this report. Construction plans for these two components are still in the preliminary 

design phase; therefore, subsequent environmental documents will be needed. 

Fish 

Impacts from blasting and dredging are expected to directly and indirectly affect plankton in the 

surrounding water column and fish in the reservoir. Blasting and dredging could increase the 

amount of mercury and methylmercury in the water column, as well as sediment, thus decreasing 

the amount of light available. However, sediment suspended during construction would be 

minimized, to the extent possible with the use of sediment curtains, sheetpiles or other methods 
Revised Draft- Subject to Change 26

that minimize the suspended sediment and keep it localized. It is anticipated that these impacts 

would be temporary, although they could affect fish in the area. Although total mercury 

levels in the sediment are at or below toxicity guidelines, those guidelines are based only upon 

direct sediment mercury toxicity to benthic organisms and do not address mercury methylation 

and bioaccumulation in the food chain. 

Wildlife

About 97 acres of existing habitat for wildlife species (does not include the “other” or annual 

grassland cover-types) would be temporarily lost with implementation of the project. The 

compensatory mitigation is intended to offset this loss of habitat value over the life of the 

project. 

Impacts from dredging and blasting are expected to temporarily increase the amount of mercury 

and methylmercury in the water column and in aquatic species including fish and some terrestrial 

species around the work area. Animals that feed on the aquatic species subject to this higher 

than typical level of mercury could be adversely affected through impaired reproduction. 

Lower American River 

Vegetation

No change in the existing conditions for vegetation in the Lower American River is anticipated; 

because the construction impacts of any Folsom Dam raise would be focused on the flood 

control space within the reservoir and lands adjacent the existing reservoir. At the current time 

neither Reclamation nor the Corps has the authority to deviate from the current Water Control 

Manual thus operations of the dam will remain the same. 

Fish

The Lower American River has been designated as impaired under the Clean Water Act, section 

303(d) for methylmercury and Lake Natoma has health advisories for mercury in fish. Efforts 

should be made to minimize suspension of sediments during the blasting and dredging 

operations, monitor suspended sediment transport out of the reservoir during those operations, 

and monitor methylmercury in unfiltered water and suspended sediment that does move out of 

the reservoir to assess methylmercury loading into the Lower American River during the blasting 

and dredging operations. 

Wildlife

No change in wildlife species numbers or species composition is expected to occur along the 

Lower American River as a result of the proposed work at the Folsom Facilities. 

OPERATIONAL IMPACTS

In 2001, the Corps proposed enlargement of the existing Folsom Dam outlets as part of the 

authorization under the American River Watershed Investigation, Folsom Dam Modification 

Project, which directed the Corps to change the variable flood storage space at Folsom Reservoir 

from the current interim operation of 400,000 acre-ft to 670,000 acre-feet to a 400,000 acre-feet 

to 600,000 acre-feet (400/600) permanent variable flood space operation once the Folsom 
Revised Draft- Subject to Change 27

Modification Project had been implemented. This change would increase the level of flood 

protection by enabling operators to balance outflows with inflow early in the storm hydrograph, 

and attain a maximum discharge of 115,000 cfs through the enlarged outlets for a 10-year or 

larger event. At that time the Service analyzed the impact of the revised Folsom Dam 

Modification Project to the cold water pool, gravel movement and seed dispersal. The Services’ 

Fish and Wildlife Coordination Act Report for the American River Watershed Investigation, 

Folsom Dam Outlet Modification Project is located in Appendix D. 

When the Folsom DS/FDR project is completed, Folsom Dam will have four methods of 

discharging flows from the reservoir: three power penstocks, eight flood control outlets, 

tainter/radial spillway gates set near the main spillway crest (five service and three emergency), 

and six submerged tainter gates in the proposed auxiliary spillway. To ensure adequate tailwater, 

the three emergency spillway gates may not be used unless the total outflow from the dam 

exceeds 240,000 cfs. This restriction makes the emergency gates unusable for normal flood 

control purposes and limits the use of the gates to dam safety outflows (Reclamation 2006b). 

The Corps and Reclamation, along with other agencies and water groups, will develop a new 

flood control manual for Folsom Dam for implementation prior to completion of the auxiliary 

spillway. The new flood control manual is currently being scoped as a parallel process. The 

parallel flood control manual development (Re-Operations Study) and study will include variable 

flood storage space, including analysis of forecast based operations, new flood release schedules 

and a plan component for repayment of potential water supply losses resulting from 

implementation of this flood control manual. This parallel study will be a collaborative process 

with the appropriate level of environmental analysis, public, agency and stakeholder 

coordination, and appropriate NEPA/CEQA documentation. However, if this does not occur, the 

project features would be operated under the existing operating criteria. Under this scenario, the 

same amount of water would ultimately be released with and without the project features (due to 

operational constraints). 

A) Folsom Reservoir

Vegetation

The enlargement of Folsom Reservoir through a raise would allow for additional flood surge 

storage capacity, on a temporary basis, and not for increasing the storage capacity of the 

reservoir. Between 805.30 and 1,389.44 acres would be affected by enlarging Folsom Dam, 

depending on which dam raise alternative is selected. Some of these lands are already developed 

or otherwise disturbed habitat, that provide little or no value for wildlife species, and some 

support vegetation that is tolerant of flooding. Table 3 summarizes the acreage of each covertype which provides value for wildlife that is expected to receive inundation over the life of the 

project (the “Other” cover-type is not included in Table 3). Inundation effects around Folsom 

Reservoir would occur in large part by the frequency, timing, and duration of flooding. 

Inundation impacts shown are for the raise components operating under the current water control 

manual/dam operations. 
Revised Draft- Subject to Change 28

Table 3. Preliminary Summary of Cover-Types, Impacted Acres and Compensation 

Recommended for the Inundated and Construction at Dikes 1-3 of the Folsom 

Reservoir for the Folsom Dam Raise Alternatives 3.5, 4.0, 7.0, or 17 feet as part of the 

Folsom DS/FDR Project, California. 

Folsom Dam Raise Alternatives 

 3.5-ft Raise 4-ft Raise 7-ft Raise 17-ft Raise 

Alternative 3-Preferred 2 4 5 

Cover Type Impacted Acres: 

Compensation Needed 

Impacted Acres: 

Compensation Needed 

Impacted Acres: 

Compensation Needed 

Impacted Acres: 

Compensation Needed 

Oak/Grey Pine 

woodland 781.5 : 939.4 820.2 : 985.8 935.1 : 1,123.8 1,331.8 : 1,600.1 

Riparian 

woodland* 45.47 : 0.02 48.68 : 0.02 56.5 : 0.02 48.68 : 0.02 

Chaparral 32.2 : 34.1 34.3 : 36.3 40.8 : 43.2 34.3 : 36.3 

Seasonal 

wetland* 0.58 : 0.0 0.58 : 0.0 0.58 : 0.0 0.58 : 0.0 

Total 859.8 : 973.5 903.8 : 995.12 1,033 : 1,167 1,415.4 : 1,636.4 

*No permanent impacts to riparian woodland and seasonal wetland are expected from the short inundation that would occur 

from a raise component of the Folsom DS/FDR project. Acres shown are from the construction at Dikes 1-3. 

Studies to date indicate that predicting the effects of inundation on vegetation is not 

straightforward. Raising Folsom Dam would have the potential for two significant impacts on 

vegetation: (1) changes in vegetation composition caused by inundation affecting survival and 

reproduction of vegetation in the zone between current and proposed maximum reservoir levels; 

and (2) effects of inundation on soil erosion and slippage, especially on steep slopes as are found 

along the upper reservoir and the forks of the American River. 

The vegetation types exposed to flooding are not, in general, highly tolerant of prolonged 

flooding. With the exception of riparian and riverine habitats, natural flooding does not occur in 

the areas which would be flooded by raising Folsom Dam. Studies of the effects of inundation 

on blue oaks (1975 in USFWS 1980; MWA-JSA 1994) have found that blue oaks can survive 

some flooding, but may be sensitive to periods of inundation of as little as 7 days. It is not clear 

from these studies, however, at what time of year flooding occurred, and the ability of vegetation 

to tolerate inundation depends on the time of year. For example, deciduous trees, such as oaks, 

tend to be much more sensitive to flooding during their period of active growth (i.e., in the 

spring), while winter-dormant plants appear to be more tolerant of flooding (USFWS 1980). 

Folsom Reservoir can be expected to fill during spring flood event, when oaks are actively 

growing. The absence of blue oaks within the inundation zone of Folsom Reservoir and other 

foothill impoundments indicates that blue oaks cannot tolerate the flooding regime existing there. 

Further, evergreen species, including grey pines and live oaks, occur commonly around the 

reservoir above current pool elevations, and tend to be more sensitive to inundation than 

deciduous trees such as blue oaks (MWA-JSA 1994). 

The other factor which could affect vegetation is erosion (slippage) of the saturated soil in the 

new inundation area during a flood event as the water is drawn down or from wind driven wave 

wash during a major storm event. Slopes in the Folsom Reservoir area are generally between 5 

and 25% (USACE 2001). Slopes in the Mooney Ridge area in the northwestern corner of the 
Revised Draft- Subject to Change 29

reservoir and the shoreline just west of the South Fork of the American River exceed 30% 

(USACE 2001). It is likely that during a major flood event some, or all, of the soil on steep 

slopes would experience some erosion. The extent of erosion and its effect on vegetation would 

be difficult to predict. 

Assuming a worst case scenario that over the life of the project all of the existing vegetation in 

the inundation zone would be lost, a mitigation need was developed for each cover-type using 

the HEP results. Statistically, there is a relatively small chance of complete inundation coupled 

with total loss of vegetation. However, it is reasonable to expect some impacts, especially at the 

lower zones due to the potential for more frequent inundation, over the life of the project. 

Given the uncertainties on effects of inundation on vegetation and soil erosion, the HEP Team 

decided to recommend that a monitoring and adaptive management program be developed to 

monitor vegetation around the reservoir over the life of the project. Baseline conditions would 

be managed and updated at 10-year, or some other predetermined interval. After major flood 

events (those which encroach above the existing maximum flood pool elevation), vegetation 

would be surveyed and damages attributable to inundation would be mitigated as deemed 

appropriate using best management practices at the time (replanting on site would be the first 

priority). 

Fish

Impacts from the rise and fall of reservoir levels could result in fish becoming stranded in 

isolated water bodies or on land, particularly if in-reservoir construction, borrow, stockpiling, 

disposal areas and haul roads are not properly re-contoured to allow complete drainage as 

reservoir levels fall. 

Wildlife

No operational effects for wildlife species are anticipated provided there is no accelerated 

erosion associated with the new inundation zone. 

Lower American River 

The raise plans would be identical to the without-project condition up to inflows of around 

300,000 cfs, or about the 140-year event. Between the 140-year event (0.7% probability of 

occurrence) and about the 200-year event (0.5% probability of occurrence), the raise plan would 

maintain outflows at no more than 115,000 cfs, while the without-project conditions would be 

uncontrolled, resulting in very high outflows of 180,000-315,000 cfs. 

Vegetation

Folsom Dam would be raised 3.5, 4.0, 7.0, or 17 feet with the project, and the additional space 

used to detain flood flows while outflows remain to the extent possible within the 115,000 cfs 

objective capacity of the downstream channel. This detention would reduce peak flows, while 

increasing the duration of flows, relative to existing conditions. The moderated flows may 

reduce erosive energy compared to existing conditions, and could have a cumulative or indirect 

effect on carryover storage. 
Revised Draft- Subject to Change 30

Fish

No long-term operational effects for fish species are anticipated. 

Wildlife

No long-term operational effects for wildlife species are anticipated. 

THREATENED AND ENDANGERED SPECIES 

Appendix B provides a list of the federally listed species for the Folsom DS/FDR project 

(Sacramento, Placer, and El Dorado counties), dated September 15, 2006, and a summary of a 

Federal agency’s responsibilities under section 7(a) and (c) of the Endangered Species Act (Act) 

of 1973, as amended. Reclamation and the Corps should get an official list of all federally listed 

and proposed threatened and endangered species and their designated critical habitat within the 

project area, or an update of any list more than 90 days old at the time preparation of any 

additional or updated Biological Assessment for this project is undertaken by accessing the 

Service’s Sacramento Fish and Wildlife Office’s website. The National Oceanic and 

Atmospheric Administration (NOAA) has responsibility for federally listed marine fish and 

wildlife species, including all anadromous salmonids. They should be contacted if any of these 

species may be impacted by project activities. The CDFG has responsibility for State listed 

species and species of concern. Species accounts for most of the species discussed below may 

be obtained from the Service’s Sacramento Fish and Wildlife Office. 

Based on the county lists there are 13 federally listed threatened species which may occur in the 

project area. These are: bald eagle, giant garter snake, California red-legged frog and its critical

habitat, delta smelt and its critical habitat, Lahontan cutthroat trout, Central Valley steelhead, 

Central Valley spring-run Chinook salmon and its critical habitat, valley elderberry longhorn 

beetle and its critical habitat, vernal pool fairy shrimp, Layne’s butterweed, California tiger 

salamander and its critical habitat, slender Orcutt grass (and critical habitat for vernal pool 

plants), and delta green ground beetle. 

There are nine federally listed endangered species which may occur in the project area. These 

are: vernal pool tadpole shrimp, Conservancy fairy shrimp (and critical habitat for vernal pool 

invertebrates), winter-run Chinook salmon and its critical habitat, Stebbin’s morning glory, Pine 

Hill ceanothus, Pine Hill flannelbush, El Dorado bedstraw, Antioch Dune evening-primrose, and 

Sacramento Orcutt grass (and critical habitat for vernal pool plants). 

DISCUSSION 

Mitigation Planning Goals

The recommendations provided herein for mitigation and the protection of fish and wildlife are 

in conformance with the Service's Mitigation Policy as published in the Federal Register (46:15; 

January 23, 1981). The Mitigation Policy provides Service personnel with guidance in making 

recommendations to protect, conserve, and enhance fish and wildlife and their habitats. The 

policy helps ensure consistent and effective Service recommendations, while allowing agencies 
Revised Draft- Subject to Change 31

and developers to anticipate Service recommendations and plan early for mitigation needs. The 

intent of the policy is to provide leadership to conserve, protect and enhance fish and wildlife 

species and their habitats. 

Under the Mitigation Policy, resources are assigned to one of four distinct Resource Categories, 

each having a mitigation planning goal which is consistent with the fish and wildlife habitat 

values involved. The Resource Categories cover a range of habitat values from those considered 

to be unique and irreplaceable to those believed to be much more common and of relatively 

lesser value to fish and wildlife. In applying the Mitigation Policy during an impact assessment, 

each specific habitat or cover-type that may be impacted by the project is identified. Evaluation 

species which utilize each habitat or cover-type are then selected for Resource Category 

determination. Selection of evaluation species can be based on several rationales, including: (1) 

species known to be sensitive to specific land and water use actions, (2) species that play a key 

role in nutrient cycling or energy flow, (3) species that utilize a common environmental resource, 

or (4) species that are associated with important resource problems, such as anadromous fish and 

migratory birds, as designated by the Director or Regional Directors of the Service. Evaluation 

species used for Resource Category determinations may or may not be the same evaluation 

elements used in an application of HEP. Finally, based on the relative importance of each 

specific habitat to its selected evaluation species, and the habitat's relative abundance, the 

appropriate Resource Category and associated mitigation planning goal are determined. 

Mitigation goals are: (1) no loss of existing habitat value (Resource Category 1); no net loss of 

in-kind habitat value (Resource Category 2); no net loss of habitat value while minimizing loss 

of in-kind habitat value (Resource Category 3); and minimize loss of habitat value (Resource 

Category 4). As defined in the Service's Mitigation Policy, "in-kind replacement" means 

providing or managing substitute resources to replace the habitat value of the resources lost, 

where such substitute resources are physically and biologically the same or closely approximate 

those lost. 

Under Pacific Region Service guidance, we are also pursuing a goal of no net loss of wetland 

acreage, while seeking a net overall gain in the quality and quantity of wetlands through 

restoration, development and enhancement. Furthermore, the Service believes that wetlands 

mitigation, which is the creation of wetlands to offset losses, should only be deemed acceptable 

when losses are determined to be unavoidable and mitigation is known or believed to be 

technically feasible. Restoration of former or degraded wetlands is the preferred form of 

compensatory mitigation, followed by wetlands creation. 

In recommending mitigation for adverse impacts to any of these habitats, the Service uses the 

same sequential mitigation steps recommended in the Council on Environmental Quality's 

regulations. These mitigation steps (in order of preference) are: avoidance, minimization, 

rectification, reduction or elimination of impacts over time, and compensation. 

Impacts to four habitat types were evaluated for the Folsom DS/FDR project. These habitats, 

and their corresponding evaluation species, designated Resource Categories and associated 

mitigation planning goals are discussed below, and summarized in Table 4. 
Revised Draft- Subject to Change 32

Table 4. Evaluation Species, Resource Categories, and Compensation Planning Goals selected 

for cover-types impacted by the Folsom DS/FDR Project, California. 

Cover-Types Evaluation Resource Mitigation Planning 

 Species Category Goals 

Oak - grey pine woodland breeding birds 2 No net loss of in-kind 

habitat value 

Riparian woodland belted kingfisher, 

raptor guild 

2 No net loss of in-kind 

habitat value 

Chaparral breeding birds 3 No net loss of habitat value 

while minimizing loss of 

in-kind habitat value 

Seasonal wetlands marsh wren, redwinged blackbird, 

great blue heron 

2 No net loss of in-kind 

habitat value 

Annual grasslands raptor guild, groundforaging birds 4 Minimize loss of habitat 

value 

Other1none 4 Minimize loss of habitat 

value 

1No evaluation species were chosen because use by wildlife is minimal to none. 

a. Oak-grey pine woodland

Oak-grey pine woodland is usually dominated by a blue oak overstory, with grey pines 

interspersed at low density among the oaks. Other trees associated with this habitat type are 

California buckeye, which occurs as scattered individuals or small clumps, and interior live oak. 

On more mesic sites, such as north-facing slopes along the South Fork near Salmon Falls, live 

oaks and California black oaks replace blue oaks as the dominant oak. Understory shrubs such 

as manzanita, toyon, and shrubby oaks are often present, though typically at low densities, 

relative to tree cover. 

Oak woodland (including oak savanna) also occurs widely in the project area, particularly along 

the lower American River, and at lower foothill elevations, near Folsom Dam. Typical oak 

woodland is characterized by a fairly open canopy layer with 20-70% cover of blue and live 

oaks, and a grassy ground cover. A woody understory may be present, but is typically sparse 

where present. 

The canopy of blue oaks is typically 30 to 50 feet tall, and varies from about 30 to 80% canopy 

closure (Barbour 1988), with open areas containing shrubs and grasses. The understory is 

primarily annual grasses and forbs. Most existing stands of this type are in mature stages, with 

oaks to heights of up to 50 feet. Mature grey pines typically rise above the oaks, to heights of up 

to 75 to 100 feet. The long-term survival of this habitat type has been an issue of concern, 

because oak regeneration has been minimal for over 100 years (Holland 1976). Many factors 
Revised Draft- Subject to Change 33

have been implicated as causes for low recruitment of oaks, including browsing of seedlings, 

consumption of acorn crops by livestock and native wildlife, changes in fire dynamics, and 

possibly climatic changes and competition with introduced annual grasses (Barbour 1988; 

Verner 1988). Blue oak woodland provides high-quality wildlife habitat for a rich assemblage of 

species. In the western Sierra Nevada, 29 species of amphibians and reptiles, 79 species of birds, 

and 22 species of mammals find mature stages of this habitat suitable or optimum for breeding, 

where other, special habitat requirements are met (Verner and Boss 1980). 

Non-native annual grasses form an understory in most of the study area, and the transition from 

woodland to savanna is not clearly demarcated, but rather part of a continuum from closed 

canopy woodland to open, treeless grasslands. As a result, habitat types can grade imperceptibly 

from one to another. Where trees are absent, the habitat is designated as annual grassland. 

Because scattered oaks provide food, cover and nesting habitat unavailable in grasslands, we 

treated oak savanna as a component of oak woodland.

The evaluation species selected for Resource Category determination are breeding birds. These 

species were selected because: (1) their ecological roles (prey, predator, scavenger, etc.); (2) the 

Service has responsibilities to protect and manage many of these species under the Migratory 

Bird Treaty Act; (3) their high nonconsumptive value for bird watching; and (4) this habitat 

provides required nesting, foraging, and cover habitat for many breeding bird species. Blue oakgrey pine woodland habitat is still relatively common in the project area and region, but is 

increasingly being degraded in value and in general not exhibiting regeneration (blue oaks). 

Therefore, the Service has placed this habitat in Resource Category 2 with its mitigation 

planning goal of no net loss of in-kind habitat value. 

c. Riparian woodland

Riparian woodlands occur extensively along the lower American River, and in patches along 

perennial and intermittent streams and rivers flowing into Folsom Reservoir. Two forms of 

riparian habitat occur in the study area: riparian forest, dominated by large trees, and riparian 

scrub-shrub, consisting mostly of low shrubs. Scrub-shrub habitat occurs in more frequently 

disturbed areas (e.g., by flood-scouring or human activities), and as a stage in regeneration of 

riparian forest following disturbance. The two forms are often interspersed (e.g., a clump of 

cottonwoods in an area of shrub-scrub), and are treated together in this report, as the existing 

data is inadequate to separate them. Trees characteristic of this habitat in the study area include 

cottonwoods, arborescent willows, and oaks; understory plants include wild grape, blackberries, 

poison oak, willows, and elderberry. Scrub-shrub habitat is frequently dominated by willows, 

and often contains other shrubby riparian species and immature trees listed above. Small areas 

of emergent wetlands, characterized by cattails, occur along the lower American River, and may 

reasonably be expected to occur in riparian areas upstream of Folsom Dam. 

Riparian forests were formerly widespread in the region, but have been severely reduced by 

agricultural development, flood control measures (including channel modifications and 

vegetation removal), and decreased stream flows resulting from diversions and dams upstream. 

The riparian forest along the lower American River today is one of the larger and betterprotected remnants of this habitat, and has been recognized as a "natural area of special 

significance" in the county general plan (County of Sacramento 1993). 
Revised Draft- Subject to Change 34

Riparian vegetation provides feeding, nesting, and shelter habitat for many species which use the 

riparian zone and surrounding lands. Vegetation which overhangs or protrudes into the water 

also provides fish with cover, rearing, and food resources. Riparian habitat supports a speciesrich assemblage of breeding birds, and provides food and cover for migratory birds. Because of 

its linear distribution and the extensive edge which that provides, the value of riparian areas to 

wildlife typically far exceeds the value of an equally-sized block of non-riparian woody habitat. 

Belted kingfishers, and raptors (including red-shouldered hawk, osprey, and American kestrel) 

were chosen to evaluate riparian habitat because: (1) as predators, they play a key role in 

community ecology of the study area; (2) they have important human nonconsumptive benefits 

(e.g., bird watching); and (3) the Service has responsibility for protection and management of 

many of these species under the Migratory Bird Treaty Act. Riparian habitat is of generally high 

value to the evaluation species, and is today very scarce in the project area and general 

Eco-region. Therefore, the Service finds that any riparian habitats that would be impacted by the 

project should have a mitigation goal of "no net loss of in-kind habitat value or acreage"--i.e., 

Resource Category 2. 

d. Chaparral 

Chaparral occurs in patches around Folsom Reservoir as well as along the south arm of Folsom 

Reservoir, and along the North and South Forks. Chaparral has a dense overstory of woody 

evergreen shrubs, and usually is found on drier sites, e.g., on southwest-facing slopes, and on 

shallow soils. Chaparral in the study area is often dominated by chamise, with manzanita, 

ceanothus, toyon, and shrubby oaks. Understory growth tends to be sparse, and is mostly annual 

grasses with a few forbs. Chaparral plants are notable for their high tolerance to drought, ability 

of seeds and/or plants to survive fire, and their high value as watershed cover (USFWS 1991). 

Chaparral provides food resources, shelter, and breeding sites to many wildlife species; for 

example, chaparral on the western slope of the Sierra Nevada provides suitable or optimal 

nesting or breeding habitat for about 90 avian species, 10 amphibians, 18 reptiles and 41 

mammals (Verner and Boss 1980). 

Breeding birds were chosen to evaluate chaparral habitat because: (1) they play multiple roles in 

chaparral ecology, as predators, prey, and as seed dispersal agents; (2) they provide 

nonconsumptive recreational and other values to humans (e.g., bird watching, bird song); and 

(3) the Service is responsible for protection and management of many of these species under the 

Migratory Bird Treaty Act. Chaparral habitat is a native habitat of generally high value to the 

evaluation species, and is today moderately scarce in the project area, but fairly abundant in the 

eco-region. Therefore, the Service finds that any chaparral habitats that would be impacted by 

the project should have a mitigation planning goal of "no net loss of habitat value while 

minimizing loss of in-kind habitat value"--i.e., Resource Category 3. 

e. Seasonal wetlands 

Seasonal wetlands occur in small patches near seeps and springs, and in drainages entering 

Folsom Reservoir. Seasonal wetlands in the project vicinity are characterized by non-woody 

emergent vegetation, including cattails, rushes, and sedges. Two marsh-nesting passerine birds, 

the marsh wren and red-winged blackbird, as well as great blue heron were chosen to evaluate 

emergent wetland. The marsh wren and red-winged blackbird are passerine species which nest 

and feed in emergent wetlands, and could therefore be present in any occurrences of this cover 
Revised Draft- Subject to Change 35

type which may be found in the project area. Great blue herons forage extensively in wetlands 

on aquatic vertebrates; these herons are a highly visible species, which many people take great 

pleasure in observing. All of the evaluation species are also migratory birds for which the 

Service has management responsibility under the Migratory Bird Treaty Act. 

In the project vicinity, and the eco-region (Central Valley) in general, emergent wetlands are 

relatively scarce, and would be of high value to the evaluation species. Emergent wetland in the 

project area is therefore designated as Resource Category 2, with a mitigation planning goal of 

“no net loss of in-kind acreage or habitat values, whichever is greater.” 

f. Annual grasslands 

Annual grasslands differ from woodland by lacking dominant tree cover; it appears that much of 

the treeless grassland found on the study area is a result of tree loss due to human activities. 

Perennial grass species once dominated native grasslands, but introduced annual species have 

largely displaced native perennial and annual grasses. Typical annual grass species are foxtail, 

brome, wild oats, and Italian ryegrass; native perennial grasses include needlegrasses, California 

onion grass, and fescue. Grassland areas provide habitat for granivorous birds such as western 

meadowlark, California quail, and sparrows and finches, and for California voles and pocket 

gophers. These areas provide important foraging habitat for breeding raptors, including redtailed hawks, American kestrels, and great horned owls, and for wintering raptors. Lastly, 

waterfowl, notably Canada geese, graze on green vegetation in the grasslands adjacent to Folsom 

Reservoir. 

The evaluation species selected for annual grasslands in the area near Folsom Reservoir are the 

raptor guild, and passerine ground-foraging birds (including western meadowlark, whitecrowned sparrow. We have chosen these as evaluation species because: (1) raptors, as 

predators, play a key role in community ecology of the study area; (2) they have important 

human nonconsumptive benefits (e.g., bird watching); and (3) the Service's responsibilities for 

many of these species protection and management under the Migratory Bird Treaty Act. While 

the values of these habitats vary according with season and grazing intensity, much of the 

grassland habitat in the study area provides medium-to-high value foraging habitat for diverse 

assemblages of birds of prey and ground-foraging passerine birds. Furthermore, the value of 

these habitats is often enhanced by their continuity with other adjacent habitats, such as wooded 

areas, cliffs, ponds, which provide nest and shelter sites. Grassland habitat has medium-to-high 

value, and is relatively abundant in the project area. Therefore, the Service finds that grasslands 

in the project should have a mitigation planning goal of no net loss of habitat value while 

minimizing loss of in-kind habitat value (i.e., Resource Category 3). 

g. “Other” habitat 

“Other” habitat includes disturbed areas such as parking lots, roads, and boat ramps. Evaluation 

species were not chosen, because use by wildlife is so minimal. In view of the extremely low 

habitat value for most wildlife species provided by these areas in the project footprint, the 

Service finds that any highly disturbed habitats meeting the “other” habitat definition that would 

be impacted by the project should have a mitigation planning goal of "minimize loss of habitat 

value" (Resource Category 4). 
Revised Draft- Subject to Change 36

Our recommended mitigation plans are based on the fundamental assumption that in-kind 

compensatory mitigation, namely creation or restoration of the desired habitats, will succeed in 

replacing the habitat functions, values, and acreage lost with project implementation. 

To provide assurance that any implemented compensatory mitigation measures will achieve their 

intended objective of replacing lost habitat values, detailed, long-term mitigation monitoring and 

remedial-action plans must be incorporated into the project design. These plans should include 

planting design, monitoring methods, specific success criteria, and remedial measures in the 

event of failure in meeting success criteria. The Service would be willing to participate in 

monitoring of construction activities, and development and implementation of the mitigation and 

monitoring programs. 

The results and recommendations in the discussion that follows are for compensatory mitigation 

of impacts due to implementation of the project. They do not supersede our primary 

recommendation for impact avoidance, as discussed previously in this report. The results and 

mitigation recommendations are based on our HEP analyses (Appendix A) which include: field 

surveys, review of aerial photographs, data collection, review of the literature and discussions 

with plant ecologists and other experts familiar with the project area and its ecological processes. 

These plans were selected based on what the Service views as most appropriate for replacing 

habitat values that would be lost with the project. They are conceptual in nature, with 

management goals outlined in each cover-type impact section below. Mitigation site selection 

should be based on this conceptual framework, and designed to coincide as much as possible 

with the construction plans in order to minimize project costs. Adverse construction impacts at a 

proposed mitigation site, such as the removal of topsoil in borrow areas could, however, reduce 

or negate the suitability of the site for revegetation efforts. In addition, numerous site-specific 

factors which are currently unknown, such as groundwater depth, surface hydrology, and 

presence of soil contaminants, also can affect a site's suitability for restoration or creation. 

Therefore, mitigation site selection should be considered preliminary until such time as complete 

evaluation of suitability of a site is completed (i.e., evaluations of soil condition, surface 

hydrology, groundwater depth, and conditions in regard to salinity, alkalinity or toxic 

substances). 

The HEP evaluation of mitigation sites is based upon the assumption that woody vegetation 

would be allowed to grow to maximum plant and canopy densities. These areas would not be 

disced or burned as part of any operation and maintenance plans, so predicted habitat values 

would be gained by this management plan. For the HEP analyses, we assumed that these areas 

would be free from human disturbance. If alternative areas would be used for mitigation that 

have greater exposure to human disturbance, the HEP analysis would need to be reviewed. 
Revised Draft- Subject to Change 37

Construction Impact Mitigation Sites (Folsom Reservoir)

The following tables (Tables 5-8) summarize the actions proposed at each hypothetical 

mitigation site used to complete the HEP analyses. Additional information is contained in the 

HEP report (Appendix A). 

Table 5. Oak - Grey Pine Woodland Mitigation Site Development Criteria, 

 Folsom DS/FDR Project, California.

OAK-GREY PINE WOODLAND 

·Acquire land. 

·Site is currently annual grassland. 

·Provide access and maintenance roads. 

·Plant native cover crop (seed). 

·Construct site specific irrigation system. 

·Plant 400 trees per acre using 4"x4"x14" tree pots. 

·Plant 90% oak tree species (blue and live oak); 10% grey pine. 

·Provide watering, weeding, non-native and invasive species control. 

·Provide pest control as needed. 

·Provide general maintenance and cleanup of site in perpetuity. 

·Monitor plantings for 3 years and take remedial actions as needed to ensure plant establishment and 

overall success of the mitigation effort. 

 ·Prepare and submit monitoring reports to the Service for 3 years. 

·Develop O&M Manual. 

Table 6. Riparian Mitigation Site Development Criteria, Folsom DS/FDR Project, California 

RIPARIAN WOODLAND

·Acquire land. 

·Site is currently annual grassland. 

·Provide access and maintenance roads. 

·Complete earthwork to facilitate seasonal natural flooding 

·Construct irrigation system. 

·Plant overstory comprised of oaks, willows and cottonwood trees using 4"x4"x14" tree pots at density 

of 200/acre. 

·Plant understory comprised of wild rose and wild grape at a density of 200/acre. 

·Plant native cover crop (seed). 

·Provide watering, weeding, non-native and invasive species control. 

·Provide pest control as needed. 

·Provide general maintenance and cleanup of site in perpetuity. 

·Monitor plantings for 3 years and take remedial actions as needed to ensure plant establishment and 

overall success of the mitigation effort 

·Prepare and submit monitoring reports to the Service for 3 years. 

·Develop O&M Manual. 
Revised Draft- Subject to Change 38

Table 7. Seasonal Wetland Mitigation Site Development Criteria, Folsom DS/FDR Project, 

California. 

SEASONAL WETLAND 

·Acquire land. 

·Site is currently annual grassland. 

·Provide access and maintenance roads 

·Construct wetland so that 40% of the area has water 4-9 inches deep in summer. 

·Plant native cover crop on area disturbed from construction area. 

·Plant appropriate wetland species. 

·Provide weeding, non-native and invasive species control. 

·Provide irrigation, pest control and monitoring reports for a minimum of 3 years or until the vegetation 

is self-sustaining. 

·Provide general maintenance and cleanup of site in perpetuity. 

·Develop O&M Manual. 

Table 8. Chaparral Mitigation Site Development Criteria, Folsom DS/FDR Project, California. 

CHAPARRAL

·Acquire land. 

·Site is currently annual grassland. 

·Provide access and maintenance roads. 

·Complete earthwork to facilitate seasonal natural flooding 

·Construct irrigation system. 

·Plant chaparral species. 

·Plant native cover crop (seed). 

·Provide watering, weeding and non-native and invasive species control. 

·Provide general maintenance and cleanup of site in perpetuity. 

·Monitor plantings for 3 years and take remedial actions as needed to ensure plant establishment and 

overall success of the mitigation effort 

·Prepare and submit monitoring reports to the Service for 3 years. 

·Develop O&M Manual. 

Operation Impact Mitigation Sites (Folsom Reservoir)

Since there are uncertainties on effects of inundation on vegetation and soil erosion and 

relatively small chances for a major flood event, it is recommended that a monitoring and 

adaptive management program be developed to monitor vegetation around the reservoir over the 

life of the project. Baseline conditions would be established and updated at intervals (10 years). 

After major flood events (those which encroach above the existing maximum flood pool 

elevation), vegetation would be surveyed and damages attributable to inundation would be 

mitigated as deemed appropriate using best management practices at the time (replanting on site 

would be the first priority). However, because the maximum pool could be lower with the 

Preferred Alternative than under existing conditions, potential impacts to vegetation and wildlife 

from inundation resulting from extreme hydrologic events may be less with the project than 

under existing conditions. 
Revised Draft- Subject to Change 39

RECOMMENDATIONS 

The recommendations contained within this section constitute what the Service believes, from a 

fish and wildlife resource perspective and consistent with our Mitigation Policy, to be the best 

present recommendations for the project. The outcomes of any new or renewed consultations, as 

required under section 7 of the Endangered Species Act or the Fish and Wildlife Coordination 

Act, could also affect the recommendations herein. Rationale for most of the recommendations 

was discussed earlier within this report. 

The Service recommends that Reclamation and the Corps implement the following preliminary 

recommendations if a Folsom DS/FDR project is pursued. As additional project information is 

developed these basic recommendations will be further refined. 

GENERAL 

o Select a flood control alternative which avoids, to the extent possible, 

unmitigable impacts and minimizes other impacts to fish and wildlife resources. 

o Consult with the Service and the National Marine Fisheries Service pursuant to 

section 7 of the Endangered Species Act, to minimize adverse affects to 

federally listed species and their habitats. 

o Consult with the California Department of Fish and Game regarding potential 

impacts to State listed threatened and endangered species. 

o Avoid impacts to oak-grey pine woodland, riparian areas and seasonal wetlands 

adjacent to, but outside of, construction easement areas through use of 

construction fencing. 

o Avoid impacts to woody vegetation at all staging areas, borrow sites, and haul 

routes by enclosing them with fencing. 

o Avoid impacts to water quality at Lake Natoma and Folsom Reservoir when 

loading, unloading, and transporting materials to be used for the Folsom 

DS/FDR project by taking appropriate measures to prevent soil, fuel, oil, 

lubricants, etc. from entering into these waters. 

o Minimize impacts to wildlife by using eco-friendly erosion control blankets that 

do not create wildlife entrapment issues. Using flexible joint netting or another 

erosion control alternative that doesn’t include monofilament fixed-joint netting 

would avoid entrapment issues that may occur with the fixed joint netting 

commonly used in erosion control blankets. 

o Minimize impacts to annual grassland habitat and other disturbed areas, by reseeding all disturbed areas with appropriate native grass species as construction 

elements are completed. 
Revised Draft- Subject to Change 40

o Minimize impacts to fish and phytoplankton during spillway construction 

(dredging and blasting) by implementing conservation and minimization 

measures (such as a curtain) during in-reservoir activities to minimize 

sedimentation and localize methylmercury dispersal.

o Compensate for unavoidable impacts to oak-grey pine woodland habitat by 

acquiring suitable lands and developing oak woodland habitat using the 

assumptions contained in Appendix A. Compensation acreages by project 

components are summarized in Appendix C. 

o Compensate for unavoidable impacts to riparian habitat by acquiring suitable 

lands and developing riparian habitat using the assumptions contained in 

Appendix A. Compensation acreages by project component are summarized in 

Appendix C. 

o Compensate for unavoidable impacts to seasonal wetland habitat by acquiring 

suitable lands and developing seasonal wetland habitat using the assumptions 

contained in Appendix A. Compensation acreages by project components are 

summarized in Appendix C. 

o Compensate for unavoidable impacts to chaparral habitat by acquiring suitable 

lands and developing the needed mitigation of chaparral habitat using the 

assumptions contained in Appendix A. Compensation acreages by project 

component are summarized in Appendix C. 

o Develop a monitoring and adaptive management program with the other 

agencies, to monitor vegetation around the reservoir over the life of the project. 

Baseline conditions would be established and updated at intervals (10 years). 

After major flood events (those which encroach above the existing maximum 

flood pool elevation), vegetation would be surveyed and damages attributable to 

inundation would be mitigated as deemed appropriate using best management 

practices at the time (replanting on-site would be the first priority). Budget in 

advance for this monitoring and adaptive management program. 

o Develop a monitoring and adaptive management plan with the other agencies, to 

monitor the hydrology and vegetation at Mormon Island Preserve. Baseline 

conditions would be established before construction begins in the area and 

would continue for 4 years after construction has been completed. Postconstruction surveys would monitor for potential changes in wetland hydrology, 

water quality, and vegetation. If changes in wetland hydrologic function are 

detected from the baseline condition, implement adaptive management 

mitigation to return affected systems to baseline conditions considering the 

long-term conservation of the Mormon Island Preserve. 
Revised Draft- Subject to Change 41

o Develop operation and maintenance manuals (O&M Manual) for all mitigation 

sites developed for the project. Coordinate with the Service on the development 

of the all O&M Manuals. 

o Monitor methylmercury levels in water and suspended sediment of water being 

released from Folsom Dam during in-reservoir construction activities until 

levels return to baseline. 

o Complete a more thorough assessment of freshwater sediment effect levels for 

contaminants of concern, in particular mercury and nickel. Many of the 

references used in Reclamations’ Sediment Characterization document to 

identify effect levels were inappropriate for fish and wildlife assessment needs. 

Other references such as MacDonald et al. (2000) and EPA (2004) provide good 

assessment guidelines for freshwater sediment. 
Revised Draft- Subject to Change 42

LITERATURE CITED 

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Vegetation, eds. M.G. Barbour and W.D. Billings. Cambridge University Press, Cambridge. 

Burwell, Trever 2006. Sacramento County Parks, Sacramento California. Personal 

Communication. 

California Department of Fish and Game (CDFG). Nimbus Hatchery Salmon [Online] Available 

http://www.dfg.ca.gov/lands/fh/nimbus/salmon.htm, September 29, 2006. 

County of Sacramento. 1993. Conservation Element of the County of Sacramento General Plan. 

Planning and Community Development Department. 

Environmental Protection Agency (EPA). Mercury Study Report to Congress: Overview 

[Online] Available http://www.epa.gov/mercury/reportover.htm, September 28, 2006. 

Gaines, D.A. 1977. The valley riparian forests of California: their importance to bird 

populations. Pages 57-85 in Riparian forests in California: their ecology and conservation. A. 

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inundation-mortality study of the proposed Auburn flood control facility. 

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Project, Draft Environmental Impact Statement/Environmental Impact Report. Vol. 1: 

Backcheck Draft, Folsom, California. 

_____. 2006a. Joint Federal Project Auxiliary Spillway Folsom Lake; Sediment 

Characterization Trace Mercury and Total Metals, Quality Assurance Project Plan. 

June 7, 2006. 

_____. 2006b. Folsom Dam Safety and Flood Damage Reduction- Draft Environmental Impact 

Study/Environmental Impact Report. December 2006. 
Revised Draft- Subject to Change 43

USFWS (U.S. Fish and Wildlife Service). 1980. Impact of water level changes on woody 

riparian and wetland communities. Vol. VII, Mediterranean Region: Western arid and semi-arid 

Region. Office of Biological Services, U.S. Fish and Wildlife Service. FWS/OBS-78/93. 

_____. 1986. Potential impacts to fish and wildlife from some alternatives actions for 

increasing flood control along the lower American River, California. Sacramento, CA. 

_____. 1991. American River Watershed Investigation, Auburn Area, Substantiating Report. 

U.S. Fish and Wildlife Service, Sacramento, CA. 

_____. 1991a. American River Watershed Investigation, Lower American River Area, 

Substantiating Report, Vol. III. U.S. Fish and Wildlife Service, Sacramento, CA. 

_____. 1994. Planning Aid Report for the American River Watershed Investigation, Raising of 

Folsom Dam Alternative. U.S. Fish and Wildlife Service, Sacramento, CA. 

_____. 1995. Working Paper on restoration needs: habitat restoration actions to double natural 

production of anadromous fish in the Central Valley of California. May 9, 1995. Prepared for 

the U.S. Fish and Wildlife Service under the direction of the Anadromous Fish Restoration 

Program Core Group. Stockton, California. 

_____. 2001. U.S. Fish and Wildlife Coordination Act Report for the American River 

Watershed Investigation Folsom Dam Outlet Modification Project, California. U.S. Fish and 

Wildlife Service, Sacramento, CA. 

_____. 2003. U.S. Fish and Wildlife Coordination Act Report for the American River 

Watershed Investigation Long-Term Evaluation. U.S. Fish and Wildlife Service, Sacramento, 

CA. 

Verner, J. 1988. Blue oak-digger pine. In: A Guide to Wildlife Habitats of California. 

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Verner, J. and A.S. Boss (tech. coords). 1980. California Wildlife and Their Habitats: Western 

Sierra Nevada. U.S. Dept. of Agric. Forest Service Gen. Tech. Report PSW-37. Berkeley, Calif.