WSP07965

• File Number: 8446
• Description: Cache La Poudre Project
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 7/1/1983
• Title: Cache La Poudre Project Study and Related Correspondence
• Water Supply Pro - Doc Type: Report/Study

2. Operation of the Bxisting Syst_

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Four major irrigation companies control and utilize 80 to 90 percent
of the total flow in the Cache la PoudreRiver. These are the North poudre
Irrigation Company, the Water Supply and Storage Company, the Larimer and Weld
Irrigation Company and, the New Cache la Poudre Irrigation and Reservoir
Company.

There are well over 100 storage reservoirs in the Cache la Poudre
River Basin. The relationship of the major reservoirs within the total
i.nterconnected system can be seen on the schematic shown on Figure 11-3 and
the larger ones are identified on the maps .on Figure 11-1 and Figure 11-4.

The total number of diversion facilities along the Cache la poudre
River and tributaries is well over 200. In addition to diversion facilities,
there are several major reservoir outlet channels which have the capability of
returning flows to the river. The relationship of these facilities within the
total system can be seen on the schematic shown on Figure 11-3 and the major
ones are identified on the maps on Figure ~I-l and Figure 11-4.
There are several facilities which import water into the Cache la
Poudre River Basin. The major transbasin import facility is the Hansen Supply
Canal which brings water into the lower basin from the Colorado River Basin
through the Colorado-Big Thompson project facilities. The remaining
transbasin import facilities bring water into the headwaters of the upper
basin from the Colorado River Basin, Michigan River Basin, and Laramie River
Basin. The relationship of these facilities can be seen on the schematic
shown on Figure 11-3 and on the maps on Figure 11-1 and Figure 11-4.

Diversions from the Cache la Poudre River are practiced on a seasonal
basis. Diversions for municipal and iJ:\dustrial IJses occur year around;
however, these uses require higher diverSions duri'lg the period from April
through October. Diversions for direct irrigation use occur primarily during
the period from May through August with lesser diversions continuing into
September and October. In addition, some diversion to storage may occur in
the spring and fall season provided storage space is available in the lower
basin reservoirs. In some years, a small! amount of diversion to storage may
occur throughout the winter. In comp~rison to total direct diversion
requirements this winter diversion to storage is small.

In the fall, it is customary to fill the reservoirs to a level less
than their maximum storage level if water supply is available. This is to
prevent damage to the structures by severe winds during the winter and early
spring. The reservoirs are then filled to their capacity in the late spring
during a short time period by snowmelt runoff. When the reservoirs are filled
or when a downstream call for, water pr~cludes any diversions to storage,
diversion into the ditches continues un~er direct-flow priorities. Water
diverted under direct-flow priorities mus~ be directly applied to farmlands
for irrigation and may only be tempor~rily stored if ditch operations
require. It can be stored for only a few days at most.

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