C150307 Final Supplimental Impact Statement

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

CHAPTER 2
DEVELOPMENT OF ALTERNATIVES
Table 2-2(continued)
Summary of Future Uses of M&I Water by Colorado Ute Tribes and Other Project Beneficiaries
Category of M&I Use Diversion(afy) Depletion(afy)
Other Binding Uses
Navajo Nation 4,680 2,340
ALPWCD 5,200 2,600
SJWC 20,800 10,400
Estimated Operational Losses 2,235 2,235
Total for Other Uses 32,915 17,575
Total Water Use • 111,965 57,1002
Source: Dornbusch 1999;Riley 1999a;Bliesner 1999.
'In addition to the 57,100 afy depletion,the Colorado Ute Tribes are entitled to another 13,000 afy of depletion under the
Colorado Ute Indian Water Rights Final Settlement Agreement(Settlement Agreement). These additional depletions could I
come from the purchase of land and water rights and would follow a historical depletion pattern which would not result in any
additional depletions above the 57,100 afy.
I 2.1.1.3.1 Rationale for Using a Fifty(50) Percent Depletion Factor For M81 Uses
The depletion amounts shown in Tables 2-1 and 2-2 reflect a 50 percent depletion factor for M&I uses.
Several factors were important in using depletion factors different than the numbers as stated in the
Settlement Act.
I ❑ The irrigation component has been deleted from the ALP Project.
I ❑ The projected M&I uses by the Colorado Ute Tribes are non-binding which makes it difficult to
accurately project the actual diversions and corresponding return flows.
I ❑ The 50 percent depletion factor allows the Colorado Ute Tribes flexibility in the use of their
water.
I ❑ The 50 percent depletion factor allows this FSEIS to analyze effects to the river systems that
could occur depending upon the eventual use of water.
I ❑ The overall effect on the total depletion to the San Juan River at a point located downstream of
both diversions and return flows is negligible.
With these considerations,a 50 percent depletion factor was considered to be appropriate. This is a
commonly accepted rule of thumb in M&I projects for determining the amount of return flows. }
I 2.1.1.4 Future Environmental Compliance
This FSEIS addresses the settings,likely impacts,and proposed mitigation measures for the structural
and non-structural components of the alternatives. While these aspects of the proposed structural
components are well defined,the non-structural components,as well as future water uses,are
projections. The specific uses to which a water acquisition fund may be put by the Colorado Ute Tribes
in implementing the non-structural components would be determined in the future. It may include
acquisition of land and associated water rights,or other activities appropriate to the use of this fund. The r;
range of impacts would vary depending on these future uses. Similarly,the future water use projections
2.1 INTRODUCTION AND BACKGROUND 2-10