Fisheries and Aquatic Resources - Home | Energy saving

133 Pages·2006·3.71 MB·English

Resource Study Report

Fisheries and Aquatic Resources

Morgan Falls Project (FERC No. 2237)

Prepared with

G S C
EO YNTEC ONSULTANTS

March 2006
EXECUTIVE SUMMARY

A fish and aquatic resources study was conducted for Georgia Power’s Morgan
Falls Hydroelectric Project (FERC No. 2237) for the purposes of characterizing existing
aquatic communities, developing aquatic resource information for evaluating the effects
of continued project operations, and evaluating the potential for fish entrainment and
turbine-induced mortality at the powerhouse. The study area included the project
impoundment and a 12-mile segment of the Chattahoochee River downstream of the
project. Information was developed based on literature review and seasonal fishery
surveys of the Morgan Falls impoundment and the downstream reach of river.
Cold hypolimnetic releases from Buford Dam (Lake Lanier) located upstream of
the project provide a thermal regime suitable for stocked trout in a 48-mile segment of
the river. The Morgan Falls Project is located within this segment. The Georgia
Department of Natural Resources Wildlife Resources Division (WRD) annually stocks
155,000 to 160,000 rainbow trout and brown trout downstream of Morgan Falls dam.
The Chattahoochee River in the project vicinity supports at least 55 species of fish,
mostly warm-water species. WRD also annually stocks shoal bass in the downstream
reach in an effort to restore the population of this endemic species.
Georgia Power fishery surveys of the Morgan Falls impoundment collected 26
species. Common sport fishes were bluegill, yellow perch, redbreast sunfish, and
largemouth bass. Rainbow trout and brown trout comprised less than 1 percent of the
catch. Biomass was dominated by common carp, white sucker, gizzard shad, and
largemouth bass.
Fishery surveys of the Chattahoochee River downstream of Morgan Falls dam
yielded 31 species, including the sport fishes rainbow trout, brown trout, shoal bass,
largemouth bass, spotted bass, striped bass, bluegill, and redbreast sunfish. Numerically
dominant fishes were Alabama hog sucker, gizzard shad, shoal bass, bluegill, white
sucker, rainbow trout, and redbreast sunfish. Trout comprised 9.6 percent of the catch;
shoal bass accounted for 9.3 percent. Biomass was dominated by common carp, white
sucker, gizzard shad, largemouth bass, and rainbow trout.
Habitat-discharge relationships for trout developed in a comprehensive instream
flow study by the Corps show that current Morgan Falls minimum flow releases
maximize habitat for adult brown trout and optimize (balance) habitat between other
trout species and life stages in shoal habitats downstream of the project. Based on
available habitat information for shoal bass in other rivers and catch rates for shoal bass
in the Chattahoochee River, the bedrock shoals downstream of the project appear to also
provide the most important habitat for shoal bass. High stream flows are the primary

i
factor limiting the availability of shoal habitats downstream of the project. These high
flows are driven by the peaking operations of upstream Buford Dam and not by Morgan
Falls dam.
Common trends and data from other studied hydroelectric sites, including 10
projects in the southeastern U.S., indicate that small and/or young-of-year fish likely
comprise the majority of fish entrained by the Morgan Falls Project. Entrainment is
likely to be numerically dominated by species of sunfishes, herrings, yellow perch,
suckers, catfishes, minnows, and a few other species. The vast majority of entrained
fish, because of their small size, are likely to survive turbine passage into downstream
aquatic habitats. The mortality of these smaller fish is expected to be relatively low,
because they are less prone to mechanical injury from turbine passage than larger fish.
Trends in turbine passage survival at numerous studied sites with Francis turbines
predict average immediate survival rates on the order of 91 percent for small fish and 83
to 85 percent for moderate-sized and large fish.
The fact that entrainment occurs does not necessarily equate to adverse impacts to
resident fish populations. The Morgan Falls impoundment supports a relatively diverse
mix of at least 26 species, including a variety of naturally reproducing sport fishes. The
existing fisheries reflect the geographic location and habitats associated with the
Morgan Falls impoundment and Chattahoochee River, as influenced by cold-water
releases from Buford Dam. Operation of the Morgan Falls Project likely results in only
minor effects to fish populations and recreational fishing opportunities as a result of fish
entrainment and turbine-induced mortality.

ii
TABLE OF CONTENTS

1. INTRODUCTION..................................................................................................1
1.1 Objectives.........................................................................................................1
1.2 Project Overview..............................................................................................2
1.3 Study Area........................................................................................................2
1.4 Report Organization..........................................................................................3
2. STUDY METHODS...............................................................................................4
2.1 Review of Existing Information.......................................................................4
2.2 Fishery Surveys................................................................................................4
2.3 Fish Entrainment Evaluation............................................................................8
3. EXISTING FISH AND AQUATIC RESOURCES............................................10
3.1 Chattahoochee River Basin.............................................................................10
3.1.1 Mainstem Dams..........................................................................................10
3.1.2 Trout Fishery..............................................................................................11
3.2 Morgan Falls Impoundment...........................................................................13
3.2.1 Habitat.........................................................................................................13
3.2.2 Species Composition, Relative Abundance, and Biomass.........................14
3.2.3 Key Sport Fishes.........................................................................................15
3.3 Chattahoochee River Downstream of Morgan Falls Dam..............................17
3.3.1 Habitat.........................................................................................................17
3.3.2 Species Composition, Relative Abundance, and Biomass.........................18
3.3.3 Key Sport Fishes.........................................................................................19
3.4 Riverine Aquatic Habitat and Flow................................................................20
3.4.1 Habitat-Discharge Relationships................................................................21
3.4.2 Shoal Bass Habitat......................................................................................23

iii
TABLE OF CONTENTS – (Continued)

3.5 Migratory Fishes.............................................................................................25
3.6 Macroinvertebrate Communities....................................................................26
3.7 Invasive Species..............................................................................................28
4. POTENTIAL FISH ENTRAINMENT AND MORTALITY...........................29
4.1 Project Facilities.............................................................................................29
4.2 Background on Fish Entrainment and Mortality............................................29
4.2.1 Factors Affecting Fish Entrainment and Mortality.....................................30
4.2.2 Turbine Entrainment and Mortality Field Study Components...................32
4.3 Potential Entrainment at Morgan Falls...........................................................33
4.3.1 Size Distribution.........................................................................................34
4.3.2 Species Composition and Relative Abundance..........................................37
4.3.3 Seasonal Distribution..................................................................................40
4.4 Potential Mortality at Morgan Falls................................................................41
4.4.1 Francis Turbines.........................................................................................42
4.4.2 Latent Mortality..........................................................................................46
4.4.3 Indirect Mortality........................................................................................47
4.5 Discussion.......................................................................................................47
5. SUMMARY...........................................................................................................50
5.1 Existing Fish and Aquatic Resources.............................................................50
5.2 Potential Fish Entrainment and Mortality.......................................................51
6. REFERENCES.....................................................................................................53
TABLES
FIGURES
APPENDIX

iv
LIST OF TABLES

Table 1. Fishery Survey Locations in the Morgan Falls Impoundment and
Chattahoochee River Downstream of Morgan Falls Dam
Table 2. Mainstem Dams and Reservoirs in the Chattahoochee River Basin
Table 3. Trout and Shoal Bass Stocking in the Chattahoochee River, 2002-2004
Table 4. Fishes Presently Known to Occur in the Vicinity of the Morgan Falls Project
Table 5. Fishes Collected by Georgia Power in the Morgan Falls Impoundment and
Chattahoochee River Downstream of Morgan Falls Dam, Spring and Fall
2005
Table 6. Georgia Power Fishery Survey Data for the Morgan Falls Impoundment,
2005
Table 7. Georgia Power Fishery Survey Data for the Chattahoochee River
Downstream of Morgan Falls Dam, 2005
Table 8. Summary of Shoal Bass Habitat Use Measurements taken in the Ocmulgee
River, Georgia
Table 9. Turbine Characteristics of the Morgan Falls Project
Table 10. Site Characteristics and Fish Entrainment Rates for 46 Hydroelectric
Developments East of the Mississippi River
Table 11. Range of Site Physical Characteristics for Sites in Entrainment Database and
Morgan Falls Project
Table 12. Percent Entrainment Composition by Size Class at 42 Hydroelectric
Developments
Table 13. Estimated Total Length of Smallest Fish Excluded by Trash Racks with 2.5
Inches Clear Spacing

v
Table 14. Percent Entrainment Composition by Family at 43 Hydroelectric
Developments
Table 15. Percent Relative Abundance of the Top Five Entrained Species at Nine
Hydroelectric Sites in South Carolina and Georgia
Table 16. Comparison of Percent Relative Abundance by Family of Entrainment at
Southeastern Sites and Fish Community Composition in the Morgan Falls
Impoundment
Table 17. Turbine Passage Survival Estimates at Sites with Francis Turbine
Characteristics Similar to the Morgan Falls Project

LIST OF FIGURES
Figure 1. Project Location Map
Figure 2. Project Boundary Map
Figure 3. Upper Chattahoochee River Basin - Lake Lanier to Peachtree Creek
Figure 4. Chattahoochee River National Recreation Area
Figure 5. Fish Sampling Reaches in the Morgan Falls Impoundment
Figure 6. Fish Sampling Reaches in the Chattahoochee River Downstream of Morgan
Falls Dam
Figure 7. Bluegill Length-Frequency and Relative Condition in the Morgan Falls
Impoundment
Figure 8. Largemouth Bass Length- Frequency and Relative Condition in the Morgan
Falls Impoundment
Figure 9. Redear Sunfish Length-Frequency and Relative Condition in the Morgan
Falls Impoundment

vi
Figure 10. Yellow Perch Length-Frequency and Relative Condition in the Morgan Falls
Impoundment
Figure 11. Rainbow Trout Length-Frequency and Relative Condition in the
Chattahoochee River Downstream of Morgan Falls Dam
Figure 12. Largemouth Bass Length-Frequency and Relative Condition in the
Chattahoochee River Downstream of Morgan Falls Dam
Figure 13. Shoal Bass Length-Frequency and Relative Condition in the Chattahoochee
River Downstream of Morgan Falls Dam
Figure 14. Yellow Perch Rainbow Trout Length-Frequency and Relative Condition in
the Chattahoochee River Downstream of Morgan Falls Dam
Figure 15. Cross-sectional Transects of Three Major Habitat Types in the
Chattahoochee River
Figure 16. Habitat-Discharge Relationships for Trout in the Chattahoochee River
Figure 17. Weighted Usable Area-Discharge Relationships for Fishing in the
Chattahoochee River
Figure 18. Monthly Entrainment of Centrarchids at Eight Sites in South Carolina and
Georgia
Figure 19. Monthly Entrainment of Clupeids at Six Sites in South Carolina and Georgia
Figure 20. Monthly Entrainment of Threadfin Shad at Two Sites in South Carolina and
Georgia
Figure 21. Monthly Entrainment of Yellow Perch at Three Sites in South Carolina and
Georgia
Figure 22. Monthly Entrainment of Catostomids at Three Sites in South Carolina
Figure 23. Monthly Entrainment of Cyprinids at Seven Sites in South Carolina and
Georgia

vii
Figure 24. Monthly Entrainment of Ictalurids at Eight Sites in South Carolina and
Georgia

Appendix A: Morgan Falls Fish Community Data Summaries

viii
1. INTRODUCTION
This report presents the findings of the Fish and Aquatic Resources Study
conducted for Federal Energy Regulatory Commission (FERC or Commission)
relicensing of Georgia Power’s Morgan Falls Hydroelectric Project (FERC No. 2237).
Georgia Power is using the Integrated Licensing Process to develop the license
application following the Commission’s regulations at 18 CFR Part 5. The study was
conducted according to the study plan for the Morgan Falls Project approved by the
Commission on November 26, 2004. Georgia Power will use the information generated
by the study to evaluate environmental effects of its proposed action in the Preliminary
Licensing Proposal, to be filed with the Commission by October 2, 2006.
The Morgan Falls Project consists of a dam and an impoundment on the
Chattahoochee River in metropolitan Atlanta, Georgia, in Fulton and Cobb Counties
(Figure 1). Georgia Power operates the project in a modified run-of-river mode for the
purposes of power generation and domestic water supply and wastewater assimilation
for metropolitan Atlanta. The project has an installed capacity of 16.8 megawatts. The
current license expires February 28, 2009.
Georgia Power proposes to continue operating the Morgan Falls Project as it is
currently operated. The Pre-Application Document (PAD) describes the project
facilities and current operations and summarizes information characterizing the affected
environment (Georgia Power, 2004a). An Operations Primer distributed and filed by
Georgia Power (2004b) further describes project operations. Scoping Document 1
summarizes the environmental issues identified during the Commission’s public
scoping process conducted pursuant to the National Environmental Policy Act (FERC,
2004a). The approved study plan incorporates Georgia Power’s study plan (Georgia
Power, 2004c) and modifications made by Commission staff (FERC, 2004b).

1.1 Objectives
The specific objectives of the Fish and Aquatic Resources Study are to:
• Conduct fishery surveys within representative aquatic habitats to characterize
the species composition, relative abundance, and overall health of the fish
community in the Morgan Falls impoundment (Bull Sluice Lake), the project
tailrace area, and the Chattahoochee River downstream of Morgan Falls dam.

1