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

Approximately 50 percent of the New Mexico M&I supply of 38,400 AF would
return to the San Juan River as return flows. This would mean a total
net depletion of about 19,200 AF.

The city of Durango would begin receiving its 2,500 AF of M&I supply from
the Durango Pumping Plant either as a direct flow from the River or from
the Reservoir through the inlet conduit when pumps were not running.
Approximately 50 percent of this supply would return to the Animas as
return flows for a net depletion of 1,250 AF per year.

The Ridges Basin Pumping Plant (maximum capacity of 9.5 cfs) would
pump water to the La Plata Rural and Shenandoah Pipelines, depending on
demands. Eventually, 4,000 AF per year would be pumped for the domestic
water needs with 1,000 AF returning to the Animas River and 1,000 AF
returning to the la Plata drainage as return flows for a net depletion of
2,000 AF annually.

F. Place of use

Stage A includes the delivery of 41,700 AF in Colorado, of which
32,500 AF are designated for the Southern Ute and Ute Mountain Ute
Tribes. It is anticipated that this diversion will result in a depletion
of 34,600 AF. This also includes the diversion of 38,400 AF in New
Mexico, of which 7,600 AF are designated for the Navajo Nation. It is
anticipated that this diversion will result in a depletion of 19,200 AF.
The total diversion in both States is 80,100 AF, resulting in a total
depletion of 53,800 AF. In addition, a depletion of 3,300 AF will occur
as a result of evaporation from Ridges Basin Reservoir. Thus the net
annual depletion to the San Juan River as a result of the reasonable and
prudent alternative will be 57,100 AF. Reclamation's operation study for
both the 1991 opinion and this analysis of Stage A was conducted using
depletion schedules which vary from Month to Month and year to year. The
result is model outputs are in the form of average annual depletions and
not net depletions, Figure 21 shows the depletion pattern for Stage A
depletions range from a low of 22,000 AF to a high of 68,000 AF with a
annual average of 57,100 AF with rounding error of approximately 100 AF.
Figure 22 shows that 57,100 AF would be exceeded over 60% of the time
when calculated as an average annual depletion. However, the RPA
restricts the depletion to a maximum of 57,100 AF in any year until all
elements of the RPA are completed (the research is completed, year-round
flow recommendations are determined, and Reclamation provides 300,000 AF
for endangered fish 96% of the time).

Table 1 describes the Municipal and Industrial (M&I) components of
the Project. Water supply projects with on-line reservoirs normally
store spring peak flows in high water years for redistribution during low
flow periods. Since the Animas-la Plata Project is fed by an off-stream
reservoir, and the demand is less than the supply, the pattern of
depletions is directly related to demand.

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