PROJ00055

• Contract/PO #: C153015
• Contractor Name: Allenspark Water and Sanitation District
• Contract Type: Loan
• Water District: 5
• County: Boulder
• Bill Number: SB 75-468
• Loan Projects - Doc Type: Feasibility Study

IV-6

be needed to supplement this supply. The most accurate method for determining
the physical supply of a basin is when long-term stream gaging records exist.
Unfortunately, these records do not exist for either Willow or Rock Creeks.
Discussions with Allenspark residents and Water District #5, Water Commis-
sioner indicates that Willow Creek is a good year-round producer of water,
even better than Rock Creek. This is contrary to what would normally be
expected since Willow Creek at its junction with Rock Creek has a basin
area of 835 acres (1.30 square miles), while Rock Creek at the same point
has an area of 4,115 acres (6.44 square miles).

Both basins lie within the same geologic unit, the Silver Plume granite, and
collect water from high elevations. Cl imatic conditions are similar.
Willow Creek may be supplied more by springs which would tend to even out
the flow. We recommend that weir gages be installed and records collected
for Willow and Rock Creeks so that future water supply development can
proceed with good streem flow data.

By comparison of the Willow and Rock Creek basins with that of other
nearby basins having stream gage records, an estimate of average monthly
flows for a normal and dry year were made. These values are for a point
of diversion from Willow Creek upstream of Al1enspark and having a basin
area of 666 acres (1.04 square miles). The figures for Rock Creek are
for a point of diversion near the SE* of Section 35, T3N, R73W with a
basin area of 2,690 acres (4.0 square miles).

Wi J1 ow Creek - CFS* Rock Creek - CFS
Average Year Dry Year Average Year Dry Yea r
January 0.13 0.10 0.54 0.40
February 0.13 0.10 0.52 0.40
March 0.13 0.10 0.54 0.40
Apri I 0.27 0.20 1.10 0.80
May 2.18 1.20 8.81 5.00
June 6.46 3.20 26.10 13.00
July 4.35 2.10 17.60 8.70
August 1.91 1.10 7.94 4.20
Sep tembe r 1.01 0.60 4.07 2.60
October 0.52 0.40 2.11 1.6D
November 0.26 0.21 1.06 0.70
December 0.17 0.13 0.67 0.50
The Year 1.47 0.79 5.94 3.19
*CFS - Cubic feet per second (1 cfs = 449 gpm).