Powerline Plan and Environ. Assessment Jan. 2013 - Flood Control ...

Powerline Flood Retarding Structure
Pinal County, AZ
Draft Supplemental Watershed Plan
and Environmental Assessment
TABLE OF CONTENTS
1.0 SUMMARY SUPPLEMENTAL WATERSHED PLAN AND ENVIRONMENTAL
ASSESSMENT ................................................................................................................ 1-1
2.0 PURPOSE AND NEED FOR ACTION ............................................................................ 2-1
2.1 Changes Requiring Preparation of a Supplement .......................................................... 2-1
2.2 Background ................................................................................................................. 2-1
2.3 Existing Dam Condition .............................................................................................. 2-2
2.4 Inadequacies of Structure ............................................................................................. 2-4
2.5 Regulatory Considerations ........................................................................................... 2-6
3.0 SCOPE OF PLAN/EA ...................................................................................................... 3-1
4.0 AFFECTED ENVIRONMENT ........................................................................................ 4-1
4.1 Climate ........................................................................................................................ 4-1
4.2 Geology ....................................................................................................................... 4-1
4.3 Soils ............................................................................................................................ 4-3
4.4 Surface Water .............................................................................................................. 4-3
4.5 Water Quality .............................................................................................................. 4-3
4.6 Water Conveyance Infrastructure ................................................................................. 4-4
4.7 Sedimentation .............................................................................................................. 4-4
4.8 Vegetative Community ................................................................................................ 4-4
4.9 Wetlands /Significant Nexus Analysis ......................................................................... 4-5
4.10 Fish and Wildlife ......................................................................................................... 4-6
4.11 Threatened and Endangered Species ............................................................................ 4-6
4.12 Transportation ............................................................................................................. 4-8
4.13 Land Use ..................................................................................................................... 4-8
4.14 Land Rights and Relocations........................................................................................ 4-9
4.15 Important Agricultural Lands ....................................................................................... 4-9
4.16 Demographics, Minority, and Disadvantaged Populations ............................................ 4-9
4.17 Air Quality/Noise/Light ............................................................................................. 4-10
4.18 Cultural Resources ..................................................................................................... 4-10
4.19 Status of Operation and Maintenance ......................................................................... 4-12
4.20 Hazard Classification ................................................................................................. 4-12
4.21 Potential Failure Modes ............................................................................................. 4-12
USDA- NRCS Page iv January 2013
Kimley-Horn and Associates, Inc.