PROJ00400

• Contract/PO #: C153588
• Contractor Name: Greeley, City of
• Contract Type: Loan
• Water District: 3
• County: Larimer
• Bill Number: SB 89-85
• Loan Projects - Doc Type: Feasibility Study

I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I

The only gaging station on the Cache la Poudre River, which covers the entire
peri od, is at the mouth of the canyon near Fort Coll ins. The gage on the
South Fork Cache 1 a Poudre Ri ver near Rusti c has streamfl ow records from
August 1956 through September 1979. These data sets were correlated with each
other to extend the records for the gage near Rustic.

Flow records are not available for Barnes Meadow Creek above the reservoir;
therefore streamflows from a representative watershed were used to approximate
runoff from the basin. The stream gage for Fall Creek near Rustic was
selected for use in the water supply analysis because of the similarities
between the watershed characteri sti cs and si ze of the contri buti ng drai nage
areas. The streamflow records for Fall Creek near Rustic were correlated with
the South Fork Cache 1 a Poudre Ri ver near Rusti c, to extend the peri od of
record. Si nce the drai nage areas differed by a si gnifi cant percentage, the
streamflows were adjusted by the square root of the ratio of their drainage
areas--about 92 percent. The adjusted annual flows were used as reservoir
inflows from Barnes Meadow Creek.

In evaluating the water available for diverison from Joe Wright Creek,
streamflow records for the gage on the South Fork Cache 1 a Poudre Ri ver near
Rustic were adopted for use in the analysis. The diversion structure in Joe
Wright Creek is located immediately downstream from Chambers Lake. The
drai nage area above Chambers Lake is approximately 30.6 square mi 1 es, whi 1 e
the contri buti ng drai nage area above the gage on the South Fork Cache 1 a
Poudre River is about 90.3 square miles. The streamflow records were adjusted
by the square root of the rati 0 of the drai nage areas to account for the
difference in watershed size.

Discussions with the Water Commissioner for the Cache la Poudre River provided
insight for determining storable and divertib1e flows. Reservoirs in the
Cache 1 a Poudre system normally fi 11 in April and June from spri ng runoff.
The remainder of the year, senior ditches divert the entire supply for
irrigation and municipal purposes. For this investigation, only the
percentage of the annual flows which occurred in April and June were
considered storable or divertib1e. For Barnes Meadow Reservoir, the storable

1231 H

-28-