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

Powerline Flood Retarding Structure
Pinal County, AZ
Draft Supplemental Watershed Plan
and Environmental Assessment
the Corps has submitted the SNA to the U.S. Environmental Protection Agency (EPA) in January
2013.
In October 2008, a 6.9-mile reach of the Lower Gila River from Powers Butte to Gillespie Dam
was designated a “traditional navigable water” or TNW by the U.S. Army Corps of Engineers
(Corps). Therefore, the nearest TNW to the project area is the Lower Gila River from Powers Butte
to Gillespie Dam. The project limits consist of the District’s modified easement area (6,237 acres)
with the Arizona State Land Department (ASLD), which includes the FRSs, flood pool areas,
Powerline Floodway, and maintenance access roads. This SNA includes the project limits and
extends to the TNW via the Powerline Floodway, the East Maricopa Floodway (EMF) and Gila
River.
The waters analyzed do not significantly affect the chemical, physical, and biological integrity of
the downstream TNW, therefore, the waters appear not to be jurisdictional waters of the U.S.
Concurrence has not been received by the Corps or EPA as of the date of this report. Further
discussion of the SNA is provided in the “Investigation and Analysis Report” in Appendix D.
4.10 FISH AND WILDLIFE
Kimley-Horn conducted a Biological Evaluation (BE) study for the PVR FRSs Rehabilitation or
Replacement Project and is documented in the report titled “Powerline, Vineyard Road and
Rittenhouse Flood Retarding Structures Rehabilitation or Replacement Project - Biological
Evaluation” (Kimley-Horn, July 2010).
The purpose of the biological evaluation was to document the existing habitat conditions of the
project area, and document any species or species specific habitat observed during field biological
reconnaissance visits. This assessment focused on gathering general habitat information for the
project area and the potential for any threatened, endangered, candidate, or other sensitive species
or associated species habitat to occur within the project area.
The majority of the project area is flat and sparsely vegetated, with the majority of the vegetation
occurring along the ephemeral washes. Very dense mesquite bosques, containing velvet mesquite
(Prosopis velutina), blue paloverde (Parkinsonia florida), catclaw acacia (Acacia greggii), and
cottonwoods (Populus fremontii) (very rare) are present near and adjacent to the FRSs. The
mesquite bosques provide valuable food, shelter, and travel corridors for multiple mammal, avian,
and reptile species. Additionally, a higher plant species diversity was observed within the mesquite
bosques. The majority of the mesquites observed within the bosque ranged from 20-30 feet in
height. The width of the mesquite bosque ranged from 200 feet to over 650 feet. There are no fish
in the project area.
4.11 THREATENED AND ENDANGERED SPECIES
The U.S. Fish and Wildlife Service (USFWS) threatened, endangered, proposed, and candidate
species lists for Pinal (dated March 5, 2012) and Maricopa (dated January 19, 2012) Counties were
reviewed by a qualified biologist to determine species potentially occurring in the project vicinity.
A qualified biologist reviewed these lists and determined that no threatened, endangered species or
critical habitat would be affected by a future proposed project. Suitable habitat is present for the
USDA- NRCS Page 4-6 January 2013
Kimley-Horn and Associates, Inc.