WSP12668

• File Number: 8230.400.30.F
• Description: Durango RICD - Other Reports
• State: CO
• Basin: Colorado Mainstem
• Water Division: 7
• Date: 3/1/2006
• Author: W. W. Wheeler and Associates
• Title: City of Durango Boating Park Hydrology Study
• Water Supply Pro - Doc Type: Report/Study

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Imported Water and Reservoir Releases

The natural flow of the Animas River is supplemented by the following return
flows from transbasin sources and reservoir releases:

1) The Florida Mesa is irrigated by diversions from the Florida Farmers Ditch and
Florida Canal (Florida River). A portion of the Florida Mesa return flows accrues
to the Animas River downstream of the Boating Park location.

2) A portion of Pine Ridge Ditch diversions (La Plata River) is delivered to lands in
the Lightner Creek and Basin Creek basins, which are tributaries of the Animas
River. The Pine Ridge Ditch return flows to Basin Creek impact the Animas
River streamflow downstream of the Boating Park. Only the Pine Ridge Ditch
return flows from Lightner Creek accrue to the Animas River above the Boating
Park.

3) Electra Lake, located on Elbert Creek about 16 miles north of Durango, is the
only large reservoir upstream of the Boating Park. The lake has a capacity of
approximately 23,100 acre-feet and is used primarily for hydroelectric power
generation.

To estimate the available unregulated or natural streamflow at the
Boating Park, we considered the contribution of storage releases at Electra Lake.
Electra Lake releases were determined from monthly storage records, which were
obtained from the State Engineer's Office for the period of 1928 through 2004. The
Electra Lake releases are summarized in Table 6. The monthly unregulated streamflow
was calculated by subtracting the Electra Lake releases from the total observed
streamflow at the Boating Park location. Table 7 presents the unregulated streamflow
estimates during the 1928 through 2004 period, which average 568,000 acre-feet per
year.

By comparing the available unregulated streamflow with the total streamflow
amounts claimed by the RICD (Table 2), the amount of RICD flows satisfied by
unregulated sources was calculated. The unregulated streamflow contributions to the
RICD claims are summarized in Table 8. The remaining streamflow commanded by the
RICD would be satisfied by Electra Lake releases, as shown in Table 9.

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