WSP05236

• File Number: 8220.106
• Description: Animas-La Plata
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 2/26/1996
• Title: Final Biological Opinion - 1996
• Water Supply Pro - Doc Type: Biological Opinion

Hydrology for the Animas-La Plata Project

I. INTRODUCTION

In 1991 the Fish and Wildlife Service and the Bureau of Reclamation developed
an alternative to the Animas-La Plata Project that would offset the likelihood
of jeopardy and adverse modifications to critical habitat of the endangered
Colorado squawfish and razorback sucker. Based on the 1991 opinion,
Reclamation reconfigured the Project into stages to accommodate the 57,100 AF
depletion (Stage A) as part of the reasonable and prudent alternative.
Reclamation asked the Service to reconsult on the revised project. The
following narrative updates the hydrological analysis accomplished far the
1991 opinion.

A. Animas-la Plata Project

The reasonable and prudent alternative in the 1991 Biological Opinion for
the Animas-La Plata Project was based on these key items: (1) a
redistribution of releases from Navajo Dam to mimic a natural hydrograph,
(2) a 7-year period of research flows and funded fish research, and
(3) protection of the flows to Lake Powell. The 1995 consultation
retains these elements, but updates the current hydrologic conditions in
the basin with new computer modeling. This narrative describes the
changes that have occurred in the past 4 years and their effect on San
Juan River flows. These include: (1) changes in the Animas-La Plata
Project affecting diversions, depletions, and return flows, (2) minor
depletions in the basin allowed under the San Juan Recovery
Implementation Plan (SJRIP), (3) the consultation on Navajo Indian
Irrigation Project Blocks 7 and 8, and (4) reductions in return flows of
Dolores River Basin imported water into McElmo Creek. The following four
sections describe in detail the current Project and subsequent
operational and depletion changes.

1. Changes in the Animas-la Plata Project (diversions, depletions, and
return flows)

Since 1991, the Animas-la Plata Project has been revised to
accommodate the potential constraints of the limited allowable
depletion of the 1991 Opinion. Stage A includes the construction of
Ridges Basin Reservoir, the inlet pipeline, the Durango Pumping
Plant, a smaller Ridges Basin Pumping Plant, the Shenandoah and La
Plata Rural, and the Durango M&I pipelines. These facilities
represent the only delivery system associated with the depletion of
57,100 AF.

Stage A also contains a commitment to increase October and November
Animas River fish bypass flows from 125 cfs to 160 cfs. These
modifications allow the project to deliver Municipal and Industrial

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