9581

• UCREFRP Catalog Number: 9581
• Author: U.S. Bureau of Reclamation.
• Title: Final Environmental Impact Statement - Navajo Reservoir Operations Volume II Technical Appendices.
• USFW Year: 2006.
• USFW - Doc Type: Grand Junction - Durango, CO.
• Copyright Material: NO

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The model in its present configuration represents the best science available to assess the
impacts of water development on the ability to meet flow recommendations for endangered
fish and to test operating rules designed for that purpose. The presently defined operating
rules and model configuration do not indicate availability for substantial additional
depletions in the basin with the present flow recommendations. Further modification of
the operating rules and/ or improvement in the simulation of system operation in the
San Juan River would be required to demonstrate the possibility of further development
within the limits of the present flow recommendations.

Configuration for No Action Alternative.-RiverWare model representation of
the future conditions expected in the San Juan River Basin without implementing flow
recommendations is required to establish the 'baseline" against which impacts are
measured. This condition is called the No Action Alternative and was configured by
including all current depletions, all depletions that could occur without further federal
action (primarily exercise of state water rights not presently being used as identified by
Colorado and New Mexico), and all depletions for which favorable biological opinions did
not depend on implementing the action. Since Flow Recommendations would not be met, it
was assumed that the ALP Project, completion of blocks 9-11 of NIIP and 3,000 acre-feet of
minor depletions via ESA consultation would not occur. Depletions used for the No Action
Alternative appear in Table 1. The model uses operating rules to simulate historic 1973 to
1991 reservoir releases. The reservoir filled in 1973 and in 1991, releases were modified to
meet the goal of the 7-year research period (1991-1997). The No Action Alternative
depletions total about 667,000 acre-feet per year, including Dolores Projecf return flows in
McElmo Creek.

Configuration for the 250/5000 and 500/5000 Alternatives.-Model
configuration for the two action alternatives is the same, only varying with minimum
Navajo Reservoir releases. Minimum target releases are 250 ds for the 250/5000 Alternative
and 500 ds for the 500/5000 Alternative. To analyze the impacts to hydrology, the model
was configured to simulate the future condition of implementing Flow Recommendations
and include all current depletions, all depletions that could occur without further Federal
action (primarily exercise of State water rights not presently being used as identified by
Colorado and New Mexico), and all depletions which have received a favorable biological
opinion. These include 57,100 acre-feet per year for the ALP Project, 120,600 acre-feet per
year for completion of blocks 9-11 of NIIP, and 3,000 acre-feet per year for minor depletions
via inter-service Section 7 consultation.

The configuration of ALP Project was adjusted to address comments from the New Mexico
Interstate Stream COmrnission(NMISC) to the Draft Supplemental Environmental Impact
Statement for the Animas-La Plata Project (DSEIS), Colorado, and New Mexico
(Reclamation, 2000). The DSEIS contemplates the Colorado Ute Tribes leasing water
under their water rights settlement with Colorado to the San Juan Water Commission in

2 The Dolores Project, in the Dolores and San Juan River Basins, was developed by Reclamation for
irrigation, M&I, recreation, and fish and wildlife uses.

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