WSPC00304

• File Number: 8220.106.I
• Description: Colorado River Water Projects - Animas La Plata - Environmental Studies
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/15/2004
• Author: DOI-BOR
• Title: Animas La Plata Project - Environmental Commitment and Monitoring Plan
• Water Supply Pro - Doc Type: Report/Study

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flow of about 78,100 af per year with some of the return flows returning back to the San Juan
River system at locations other than the AniJ;I1as River equaling out to an average annual
depletion of 57,100 af to the San Juan River system. Impacts to existing flow are anticipated
in the San Juan River as a result of project operation that would reduce water supply for
future Indian trust water uses, Project return flow from non-binding uses could increase
flows in the La Plata River in New Mexico in an area that is now water short, Unless these
return flows are protected or the depletion of them replaced, downstream depletions would
increase above the 57,100 acre-feet per year with subsequent impact to endangered fish
flows.
a) A voidance/Minimization:
i) By Design:
(1) Ridges Basin Reservoir:
(a) Ridges Basin Reservoir will be designed with a minimum (inactive) pool of
30,000 af.
ii) By Operation:
(1) Durango Pumping Plant:
(a) Changes in pumping rates of the pumping plant would be limited and
minimum flows would be honored. See 5) Aquatic Resources below for
additional information.
(b) An operation plan will be put in place for the Durango Pumping Plant that will
schedule pumping water from the Animas River in a manner to limit impacts
to non-Colorado Ute entities ability to obtain water from the San Juan River.
Operations will be dependent upon yearly project water demand, type of water
year, and flows needed for the endangered fish recovery program in the San
Juan River.
(c) For project operation a stream flow gauging station will be constructed on the
Animas River a short distance below the intake to the Durango Pumping
Plant. The purpose of the gauging station will be to measure the flows in the
Animas River below the pumping plant for project operation and to insure
bypass commitments are being adhered to,
iii) Other:
(1) When and if Animas La Plata Project water is transported to the La Plata River
Basin for municipal and industrial (M&I) purposes, Reclamation will work with
state and federal agencies to pursue a method of protecting project water return
flow in the La Plata River drainage as a water supply for endangered fish.

2) Water Quality - The water quality of Animas River has been affected by historic mining
activities in the headwaters, naturally occurring trace elements, M&I water development and
discharges, oil and gas development, agricultural uses, and non-point source return flows.
Heavy metal problems continue to persist from early-century mining activities, There is the
potential that activities associated with construction of the project could impact the Animas
River. Construction of Project facilities could result in temporary increases in suspended
sediments loads in Basin Creek and the Animas and San Juan Rivers. Once operation of the
project begins, the river could be impacted by having less water in the river for dilution, The

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