C150307 Final Supplimental Impact Statement

• Contract/PO #: C150307
• Contractor Name: Animas La Plata
• Contract Type: Loan
• Loan Projects - Doc Type: Report

Approximately 200 af of storage space would be purchased in Red Mesa Reservoir(also referred to as
Mormon Reservoir).
In summary,approximately 36,891 af of water may become available through coordinated operation of
existing reservoirs with streamflows in the San Juan Basin. Subsequent computer modeling studies
would need to verify the amount.
The capacity of Lemon Reservoir would be increased from approximately 40,000 af to 50,000 af by
raising the dam 11.5 feet. Increased capacity would be used to deliver water to the Florida Mesa Housing
Unit and supplement Animas River diversions to meet the City of Durango demands and the Durango
regional demands. The depletion supplied by Lemon Reservoir to the uses ranges from zero to 1,500 afy,
with an average annual depletion of approximately 500 af. More detailed water operation modeling
studies would need to be completed to verify the yield from enlarging Lemon Reservoir.
A water acquisition component of Refined Alternative 6 was developed that would be commensurate
with the non-structural component of Refined Alternative 4 for the purchase of agricultural lands to
obtain 13,000 afy depletions. Under this component the water would be left on the land. A summary of
the lands purchased under this component are as follows:
❑ Animas and Florida River Basins-Acreage sufficient to provide a firm yield depletion of
6,500 af would be purchased in the Animas and Florida River Basins as an equivalent to the non-
structural component of Refined Alternative 4. The water would remain on the land as described
in Refined Alternative 4. With a depletion factor of 1.4 af per acre,4,643 acres would be
required.
❑ McElmo Creek Basin(Montezuma County)-Approximately 4,062 acres, an amount sufficient to
provide an annual firm yield depletion of 6,500 af,would be purchased in the Montezuma
Valley,either within the Montezuma Valley Company or elsewhere in the Dolores Project
service area as an equivalent to the non-structural component of Refined Alternative 4. The
water would remain on the land.
1A
SEIS Conclusions and Recommendations
The initial 10 alternatives,additional structural and non-structural components,and Refined Alternatives
4 and 6 were thoroughly evaluated in the SEIS. The analysis is included in Chapters,Volume 1 of the
FSEIS for the full range of alternatives. Additional analysis for Refined Alternatives 4 and 6 is included
in Chapters 3 and 4 of this FSEIS,Volume 1. In Chapter 5,additional analysis to test the ability of the
refined alternatives to meet the purpose and need of the project.
Project alternatives would affect resources such as streamflows, fish and wildlife,vegetation and
wetlands,cultural resources, and recreation as described in Chapter 3. Chapters 3 and 5 describe
mitigation measures and environmental commitments to reduce these impacts.
The evaluation of several factors reveals that implementation of Refined Alternative 6 presents a number
of problems:
❑ It would impose significant risks on the ability of the project to provide an assured water supply
commensurate with the water rights established in the settlement;
❑ The wholesale purchase of land and transfer of water may be opposed by the local community,
thereby impacting completion of the settlement;
ES-9