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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(b) A fish bypass pipeline will be placed at the end of the fish screens to convey
fish back to the Animas River below the intake to the Durango Pumping Plant.
(2) Ridges Basin Reservoir:
(a) Ridges Basin Reservoir will be design with a minimum operating pool of
30,000 af to conserve populations of stocked trout in the reservoir,
(b) Ridges Basin Dam outlet facilities will be designed and constructed to prevent
escapement of nonnative fish that might compete with native fish in the
Animas and San Juan Rivers and other area waterways, From the Biological
Opinion - Reclamation will implement all actions necessary to prevent
escapement of nonnative fishes from Ridges Basin Reservoir in any water
leaving the reservoir. Reclamation will consider the escapement of eggs and
larvae in the design of an escapement devise or method,
ii) General Construction:
(1) Ridges Basin Dam:
(a) As part of construction, vegetation in Ridges Basin Reservoir basin will be
largely cleared to reduce the magnitude of productivity and reduction potential
(methylated mercury) once the reservoir is filled. If significant
bioaccumulation effects are determined, Reclamation will work with the
appropriate local, state and federal agencies to either minimize the impact or
otherwise offer protection to potentially impacted fish and wildlife species and
to possibly post human consumption advisories, Trout will be the only fish
stocked in Ridges Basin Dam.
iii) By Operation:
(1) Durango Pumping Plant:
(a) Changes in pumping rates of the pumping plant are not to exceed 50 cfs per
hour increase and 100 cfs per hour decrease when flows in the Animas River
are above 500 cfs. When river flows are below 500 cfs increases in pumping
rates will not exceed 25 cfs per hour and decreases in pumping will not exceed
50 cfs per hour.
(b) Reclamation will honor minimum bypass flows for the Animas River, as
measured immediately downstream of the Durango Pumping Plant. The
purpose of the bypass flows will be to avoid/minimize flow-related impacts to
aquatic (including trout and native species) and wetland/riparian habitat
resources. Bypass flows will vary according to season of year, and will remain
in effect throughout the life of the Project. The minimum bypass flows for the
Animas River will be:
(i) 225 cfs from April 1 to September 30,
(ii) 160 cfs from October 1 to November 30,
(iii)125 cfs from December 1 to March 31.
(c) There will be no flow augmentation provided by the Project other than Project
return flows and Project releases down Basin Creek for Project water users
downstream.
(d) If it is concluded that operation of the Project is having significant adverse
impacts to the downstream aquatic ecosystem, Reclamation will make every

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