PUB00053

• Year: 1999
• Title: Metropolitian Water Supply Investigation Final Report
• Author: Hydrosphere Resource Consultants
• Description: Metropolitian Water Supply Investigation Final Report
• Publications - Doc Type: Water Resource Studies

Metropolitan Water Supply Investigation

MWSI Results

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2. There must be surface supply in excess of the amount needed to meet demands
and fill existing reservoirs.

3. They would rely on existing surface water collection and importation facilities,

Based on a review of existing information, several sources of potential surface supplies
were initially identified and considered, These included:

1. Denver's unused divertible supplies from the South Platte and Colorado basins,
including South Platte free river water.

2. Aurora's unused divertible supplies from the Arkansas and Colorado basins.

3. Water from the Colorado-Big Thompson and Windy Gap projects.

4. Excess surface water from local tributaries such as Cherry and Plum Creeks,
during precipitation events.

5. Excess South Platte flows occurring below Denver,

6. First use of South Platte irrigation rights.

Denver's Unused Divertible SUDDlies

In most years, more water is available to Denver Water's collection system and water
rights than can be delivered or stored. Denver's "unused divertible" supplies are one
potential source of surface water that could be used in a conjunctive use plan. The
amount available would be subject to Denver's future needs and water development
plans, water rights constraints, environmental concerns and West Slope issues.

When Phase II of the MWSI began exploring conjunctive use, Denver was beginning its
Integrated Resource Planning (IRP) process and its current P ACSM model was not
complete. An initial estimate of Denver's unused divertible supplies was therefore
obtained from earlier Denver modeling studies done as a part of the Two Forks EIS. This
initial estimate was based on monthly data and showed Denver's unused divertible
supplies as averaging 85,000 acre-feet per year over the 1947 - 1974 period of hydrologic
record. These supplies represented combined South Platte, Blue River and Fraser River
flows divertible under Denver's water rights in excess of Denver's system needs at an
assumed demand level of 335,000 acre-feet per year, which corresponded to the estimated
safe yield of Denver's existing system at that time. This estimate was used in the
MWSI's Phase II Conjunctive Use Summary Report.

Prepared for the Colorado Water Conservation Board, Colorado Department of Natural Resources by
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During Phase III of the MWSI, a revised estimate of Denver's unused divertible supplies
was developed using data from Denver's PACSM model. This second estimate was
based on daily data and showed Denver's unused divertible supplies from the Blue and
South Platte Rivers (excluding the Fraser River) plus free river water as averaging
approximately 87,000 acre-feet per year over the 1947 through 1991 period of hydrologic

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