Lower South Platte River Study

• Contractor Name: Colorado Water Conservation Board
• Loan Projects - Doc Type: Feasibility Study

Lower South Platte River Study
Colorado Water Conservation Board
December 2001
February 1954 to April 1957 (1950s Drought)
' February 1976 to November 1980 (1970s Drought)
In most years, water is consistently available in December and January with some water
available in the February to mid-April period. However, some extremely large volumes of
water are available in isolated years in the months of May and June. For example, the
analysis indicates that nearly 692,000 acre-feet would have been available in the river at the
' North Sterling Inlet Canal diversion in June 1983 and nearly 539,000 acre-feet in June 1995.
These were two extremely wet years.
Because of the extreme variability of the available water supply estimates, the development
of a dependable water supply will require storage.
' 2.5 Storage Analyses
9 Y
' A simplified spreadsheet operations model was developed by Brown and Caldwell to
evaluate potential storage options. The model covers diversions of water at the:
• North Sterling Canal Headgate
• Harmony Ditch Headgate
' • Peterson Ditch Headgate
' The canal systems supplied by these diversions could be used to fill storage in a new
reservoir by gravity or by pumping, depending on the availability of delivery capacity after
current water users on the canal are satisfied.
' As discussed in Section 2.4, water is consistently available in the river during the winter
months. However, the river headgates and the canals and ditches are very difficult to operate
' and maintain during the winter due to ice conditions. The only canal that is operated
successfully in winter is the North Sterling Inlet Canal, which is a deep v-shaped channel
' with few structures. Because of its length (>100 miles), configuration, and number of
crossing and turnout structures, the North Sterling system appears to be the least attractive
option for filling a new storage reservoir by gravity. Water to fill new storage would be
' diverted at the North Sterling Inlet, travel 50 miles to North Sterling Reservoir and another
60 miles to storage sites west of Julesburg Reservoir.
' The Harmony system is better suited to this type of operation,but is located at elevations
lower than many of the storage sites that were identified upstream of Julesburg Reservoir.
The Harmony system could be used to fill an enlarged Julesburg Reservoir and sites on the
' north side of the river downstream of Julesburg Reservoir by gravity. Water could be
pumped from the Harmony system into the storage sites topographically higher than the
ditch.
GEI Consultants, Inc. 2-9 01002 Dec 2001 Lower South Platte River Study