TABLE OF CONTENTS
I.OVERVIEW
- Introduction
- Background
- Biological Assessment Content, Scope, and Public Process
- Request for Formal Consultation
- Content and Scope
- Action: A description of the action to be considered.
- Area: "A description of the specific area that may be affected by the action."
- Species and Critical Habitat Description: "A description of any listed species or critical habitat that may be affected by the action."
- Effects of the Action: "A description of the manner in which the action may affect any listed species or critical habitat and an analysis of any cumulative effects."
- Relevant Reports: "Relevant reports, including any environmental impact statement, environmental assessment, or biological assessment prepared...."
- Other Relevant Reports: "Any other relevant available information on the action, the affected listed species, or critical habitat."
- Public Process and Consultation Schedule
II. DESCRIPTION OF ACTION
- Introduction
- The Secretarys Discretionary Management Activities
- Flood Control
- The Role of the Secretary as Watermaster of the Lower Colorado River Basin for Delivery and Storage of Water
- Declaration of Surplus
- Delivery to Mexico at the Northerly International Boundary (NIB)
- Water Delivery to Mexico at the Land Boundary near San Luis, Sonora
- Power Operations
- Channel Maintenance and Levee System
- Yuma Desalting Plant and 5-Mile Zone
- Endangered Species Conservation Activities
- Lower Colorado River Operation and Maintenance Procedures
- Flood Control
- Annual Operating Plan
- Operation of the Colorado River Below Davis and Parker Dams
- Water Delivery Requirements to Mexico in Accordance with the Mexican Water Treaty of 1944
- Process for Daily Water Requirements and Hourly Release Schedule
- Parker Dam to Mexico
- Parker Dam to Davis Dam
- Davis Dam to Hoover Dam
- Seasonal Release Patterns
- River Maintenance
- Yuma Desalting Plant and 5-Mile Zone
- Endangered Species Conservation Program
- Introduction
- Endangered Razorback Sucker and Bonytail Conservation
- Native Fish Work Group
- Willow Beach National Fish Hatchery
- HAVFISH Project
- Boulder City Golf Course Native Fish Rearing Project
- Hualapai Native Fish Rearing Facility
- Native Riparian Plant Restoration
- Native Riparian Plant Nurseries
- Demonstration Projects
- Enhancement Projects
- Research
- Three-Finger Lake Project
- Boulder City Wetland Project
- Lower Imperial Division Wetland Enhancement
- Las Vegas Wash Wetland Restoration
- Multi-Species Conservation Program Development
- Summary of Secretarys Non-Discretionary and Discretionary Operation and Maintenance of the Lower Colorado River
- Introduction
- Non-discretionary
- Varying Degrees of Discretion
- Fully Discretionary
III. ENVIRONMENTAL BASELINE
- Historic and Present Biological Communities on the Lower Colorado River
- Introduction
- Riparian Communities
- Historic
- Present
- Marsh
- Historic
- Present
- Aquatic
- Historic
- Development Along the Lower Colorado River
- Effects of Development and Present Day Aquatic Baseline
- Previous and Ongoing Section 7 Consultations
- Colorado River Mainstem
- Baseline Projects
- Central Arizona Project Havasu Diversion
- Southern Nevada Water System (Robert B. Griffith Water Project)
- Salton Sea and Endangered Desert Pupfish
- Non-Federal (Contemporaneous and Cumulative) Actions
IV. SPECIES
- Introduction
- Terrestrial
- Endangered
- Peregrine Falcon (Falco peregrinus)
- Southwestern Willow Flycatcher (Empidonax traillii extimus)
- Threatened
- Bald Eagle (Haliaeetus leucocephalus)
- Desert Tortoise (Gopherus agassizii) (Mojave & Sonoran populations)
- Proposed Threatened
Flat-tailed horned lizard (Phrynosoma mcallii)
- Sensitive
- California Leaf-Nosed Bat (Macrotus californicus)
- Spotted Bat (Euderma maculatum)
- Greater Western Mastiff-Bat (Eumops perotis californicus)
- Small-Footed Myotis (Myotis ciliolabrum)
- Allen's (Mexican) Big-Eared Bat (Idionycteris phyllotis)
- Pale Townsend's Big-Eared Bat (Plecotus townsendii pallescens)
- Long-Legged Myotis (Myotis volans)
- Fringed Myotis (Myotis thysanodes)
- Yuma Myotis (Myotis yumanensis)
- Cave Myotis (Myotis velifer)
- Yuma Hispid Cotton Rat (Sigmodon hispidus eremicus)
- Loggerhead Shrike (Lanius ludovicianus)
- Large-billed Savannah Sparrow (Passerculus sandwichensis rostratus)
- Arizona Toad (Bufo microscaphus microscaphus)
- Desert tortoise (Sonoran population) (Gopherus agassizii)
- Rosy Boa (Lichanura trivirgata)
- Cowles's fringe-toed lizard (Uma notata rufopunctata)
- Chuckwalla (Sauromalus obesus)
- Grand Wash Springsnail or Grapevine Springsnail (Pyrgulopsis bacchus)
- White Desertsnail (Eremarionta immaculata)
- Cheeseweed owlfly (aka moth lacewing, mothlike netwing, ithonid lacewing) (Oliarces clara)
- MacNeills sootywing (Hesperopsis gracielae)
- Dune sunflower, silver-leafed sunflower - (Helianthus niveus ssp. tephrodes)
- Sand food (aka sand sponge, sand root, or biatatk [Tohono O'odham word meaning "sand root," Jaeger 1940]) (Pholisma sonorae)
- Foxtail cactus (Coryphantha vivipara var. alversonii)
- Crissal Thrasher (Toxostoma crissale coloradense)
- Marsh
- Endangered
- Brown Pelican (Pelecanus occidentalis)
- Yuma Clapper Rail (Rallus longirostris yumanensis)
- Sensitive
- California Black Rail (Laterallus jamaicensis coturniculus)
- Western Least Bittern (Ixobrychus exilis hesperis)
- White-faced Ibis (Plegadis chihi)
- Fulvous Whistling Duck (Dendrocygna bicolor)
- Aquatic
- Endangered
- Colorado Squawfish (Ptychocheilus lucius)
- Razorback Sucker (Xyrauchen texanus)
- Bonytail (Gila elegans)
- Critical Habitat Description - Razorback Sucker and Bonytail
- Sensitive
- Flannel Mouth Sucker (Catostomus latipinnis)
- California floater (Anodonta californiensis)
- Mexico Species
- Desert pupfish (Cyprinodon macularius)
- Vaquita (Phocoena sinus)
- Totoaba (Totoaba macdonaldi)
- Summary of Effect Analyses
GLOSSARY OF TERMS AND ACRONYMS
APPENDICES
APPENDIX A - LOWER COLORADO RIVER MULTI-SPECIES CONSERVATION PROGRAM
APPENDIX B - CONSULTATION AGREEMENT
APPENDIX C - RIVER WORK AND MAINTENANCE
Introduction and Past History
Major Activities Along the Lower Colorado River
Mohave Valley Division
Topock Gorge Division
Havasu Division
Parker Division
Palo Verde Division
Cibola Division
Imperial Division
Laguna Division
Yuma Division
Limitrophe Division
APPENDIX D - MAJOR FACILITIES ON THE LOWER COLORADO RIVER
Laguna Dam
Hoover Dam
Imperial Dam
Parker Dam
Davis Dam
Headgate Rock Dam
Palo Verde Diversion Dam
Senator Wash Pumping/Generating Plant and Regulating Reservoir
Glen Canyon Dam
Morelos Dam
All-American Canal, Pilot Knob and Siphon Drop Powerplants
The Gila Gravity Main Canal
APPENDIX E - HISTORICAL AND PROJECTED RESERVOIR OPERATIONS ON THE LOWER COLORADO RIVER
Introduction
Historical Hoover Dam/Lake Mead Operations
Historical Davis Dam/Lake Mohave Operations
Historical Parker Dam/Lake Havasu Operations
Comparison of Projected vs Historical Operations for Lake Mead/Hoover Dam
Comparison of Projected vs Historical Operations for Lake Mohave/Davis Dam
Comparison of Projected vs Historical Operations for Lake Havasu/Parker Dam
Historical And Projected Water Use - Lees Ferry to Mexico
APPENDIX F - YUMA DESALTING PLANT OPERATION
APPENDIX G - LOWER COLORADO RIVER BASIN STUDIES - NATIVE FISH SPECIES
APPENDIX H - COE/RECLAMATION FLOOD CONTROL AGREEMENT FOR HOOVER DAM AND LAKE MEAD
APPENDIX I - CALENDAR YEAR 1995 COMPILATION OF RECORDS
APPENDIX J - BIBLIOGRAPHY/LITERATURE CITED
TABLES
Table 1. List of documents known collectively as "The Law of the River"
Table 2. List of Endangered, Threatened, Proposed Threatened, and Sensitive Species in the United States and Mexico
Table 3. Minimum and maximum flow rates for the delivery of water to Mexico at the NIB
Table 4. Chronology of Lower Colorado River Development
Table 5. 1986 acreage of lower Colorado River floodplain vegetation community types per river maintenance division
Table 6. 1994 acreages of lower Colorado River floodplain vegetation community types per river maintenance division
Table 7. Marsh types and criteria used in classification lower Colorado River
Table 8. Surface acreage of water along the Colorado River from Pierce Ferry to the U.S./Mexico Internation Boundary by river maintenance division
Table 9. Section 7 Consultations, Endangered Species Act, Lower Colorado River
Table 10. List of non-Federal activities that affect the resources of the lower Colorado River and its extended environs
Table 11. Amounts and uses of water diverted by principal water entitlement users in 1993
Table 12. Acreage comparison for cottonwood-willow and saltcedar communities/structures between 1976 and 1994
Table 13. Agency actions that have undergone section 7 consultation and levels of Incidental Take permitted for the Southwestern Willow Flycatcher range wide
Table 14. Collection records of the moth lacewing, Oliarces clara
Table 15. Collection records of MacNeill's sootywing, Pholisora graciliae
Table 16. Summary of Effect Analyses
Table C-1. Levee & bank line system for the lower Colorado River by river-miles and division
Table E1. Sum of all Colorado River use by Arizona, California, and Nevada; Lees Ferry to Mexico
Table E2. Sum of all Colorado River uses above Hoover Dam
Table E3. Sum of all Colorado River uses Hoover Dam to Davis Dam
Table E4. Sum of all Colorado River uses Davis Dam to Parker Dam
Table E5. Sum of Colorado River use by Arizona and California below Parker Dam
Table E6. Mexico use in satisfaction of Treaty
Table E7. Robert B. Griffith Water Project (SNWS) use
Table E8. Metropolitan Water District of Southern California use
Table E9. Central Arizona Project use
Table E10. Projected Colorado River use
FIGURES
Figure 1. Description area within the Colorado River Basin
Figure 2. Detail of the Colorado River description area showing river maintenance divisions
Figure 3. Location of critical habitat for bonytail and razorback sucker
Figure 4. Schematic of annual lower Colorado River releases and diversions in million acre-feet
Figure 5. Side-view schematic of lower Colorado River from Pierce Ferry to the SIB
Figure 6. Natural flow at Lees Ferry
Figure 7. Flow below Hoover Dam
Figure 8. Lake Mead end-of-month elevations - 1935 to 1996
Figure 9. Typical season flow of Colorado River below Davis Dam
Figure 10. Typical spring flows on Colorado River below Parker Dam
Figure 11. Typical summer flows on Colorado River below Parker Dam
Figure 12. Typical fall flows on Colorado River below Parker Dam
Figure 13. Typical winter flows on Colorado River below Parker Dam
Figure 14. Copy of Release Schedule (a) and Actual Release (b) from Parker Dam
Figure 15. Lake Havasu operational constraints
Figure 16. Typical dynamic power generation measured at the Hoover Dam 230-kV bus
Figure 17. Lake Mohave pre-1998 (curve A) and post-1998 (curve B) operational constraints
Figure 18. Hoover actual releases
Figure 19. Davis actual releases
Figure 20. Parker actual releases for October 28, 1994
Figure 21. Three-finger Lake Project
Figure 22. Boulder City Wetland
Figure 23. Lower Imperial Division Wetland Enhancement
Figure 24. 1879-1977 Comparison of vegetation communities along same stretch of lower Colorado River near Blythe, California
Figure 25. Historic lower Colorado River floodplain and associated vegetation communities
Figure 26. Reconstruction of native plant community placement and species composition
Figure 27. Examples of vertical configurations for the vegetation structural types
Figure 28. 1995 Colorado River delta at Lake Mead vegetation classification
Figure 29. Areas of known occurrence of desert tortoises in Arizona
Figure C-1. Quarry Sites. Map No. 423-LC-222
Figure D1. List of owner/operators for major facilities along the lower Colorado River
Figure E-1. Map and operational diagram of the lower
Colorado River [Map Number 423-300-59 (Revised April 1993)]
Figure E1. Hoover daily release
Figure E2. Hoover daily flow duration
Figure E3. Hoover daily mean release range
Figure E4. Hoover actual releases
Figure E5. Lake Mead daily elevation
Figure E6. Lake Mead daily elevation range
Figure E7. Lake Mead monthly elevation change
Figure E8. Davis daily release
Figure E9. Davis daily flow duration
Figure E10. Davis daily mean release range
Figure E11. Davis actual releases
Figure E12. Lake Mohave daily elevation
Figure E13. Lake Mohave daily elevation range
Figure E14. Lake Mohave monthly elevation change
Figure E15. Parker daily release
Figure E16. Parker daily flow duration
Figure E17. Parker daily mean release range
Figure E18. Parker actual releases
Figure E19. Lake Havasu daily elevation
Figure E20. Lake Havasu daily elevation range
Figure E21. Lake Havasu monthly elevation change
Figure E22. Hoover Dam release
Figure E23. Hoover monthly release distribution
Figure E24. Flow depth below Hoover
Figure E25. Hoover flow depth distribution
Figure E26. Lake Mead elevation
Figure E27. Lake Mead elevation distribution
Figure E28. Davis Dam release
Figure E29. Davis monthly release distribution
Figure E30. Flow depth below Davis Dam
Figure E31. Davis flow depth distribution
Figure E32. Lake Mohave operational constraints
Figure E33. Parker Dam release
Figure E34. Parker monthly release distribution
Figure E35. Flow depth below Parker Dam
Figure E36. Parker flow depth distribution
Figure E37. Lake Havasu operational constraints
Chapter I TOC |
Chapter II TOC |
Chapter III TOC |
Chapter IV TOC
Glossary of Terms and Acronyms |
Appendices |
Tables |
Figures
Assessment TOC |
COMMENTS