PUB00028

• Year: 1999
• Title: Metropolitan Water Supply Investigation Final Report
• CWCB Section: Interstate & Federal
• Author: Rozaklis and Weaver
• Description: Investigation to explore cooperative solutions to future metropolitan Denver area water supply needs to minimize conflicts
• Publications - Doc Type: Brochure

Metropolitan Water Supply Investigation

MWSI Results

3.1.2.2. Colorado River Basin

The Colorado River Basin has been a major source of water supply for agricultural and
municipal water users since the early 1900's. South Platte Basin municipal and industrial
water providers obtain about 30% of their existing water supply from the Colorado River
Basin. The areas that are most relevant to this investigation include the Colorado River
mainstem in Garfield and Mesa Counties and its headwater tributaries located in Grand,
Summit, and Eagle Counties.

Water supply sources for the Colorado River headwater counties consist primarily of the
Colorado, Fraser and Williams Fork Rivers in Grand County, the Blue River in Summit
County, the Eagle River in Eagle County. Access to water supplies from these sources in
Grand, Summit and Eagle Counties is limited primarily by the relative seniority of water
rights for transbasin diversions, and (during the late summer and winter low-flow
months) by the water rights of the Shoshone hydropower plant located downstream in
Glenwood Canyon on the Colorado River main stem. For all ofthe headwater counties,
water rights held by the Colorado Water Conservation Board for protection of instream
flows are a limiting factor during periods of drought and seasonal low-flows.

Water users in Garfield and Mesa Counties have access to water supplies from the
Colorado River main stem and its tributaries, while water users in Gunnison, Montrose,
Mesa and Delta Counties have ready access to supplies from the Gunnison River and its
tributaries.

Growing water demands throughout the West Slope consist primarily of municipal uses.
In the headwater counties, water demands for snowmaking and winter domestic use have
grown rapidly during recent years resulting in an increased need for local water supply
storage facilities. In both the headwater and main stem counties agricultural lands and
water rights are rapidly being converted to urban and municipal uses.

Water management activities and water supply availability are affected by the presence of
several endangered fish species in the Colorado River near Grand Junction. A recovery
implementation program has been created to address the needs of these species. This
program must consider the flow requirements of the endangered species, existing and
future in-basin water uses and transbasin diversions. The goal of the program is to allow
for future water development under Colorado's compact entitlement while recovering the
endangered species. Real and perceived trade-offs between these competing uses have
resulted in considerable controversy within the program.

There are also several water quality concerns within the basin related to transbasin
diversions. Transbasin diversions selectively divert higher quality headwater sources,
resulting in higher concentrations of dissolved solids and certain pollutant constituents at
lower elevations in the basin. Some transbasin diversions (primarily the CBT project and
Denver's Moffat and Roberts collection systems) have also significantly reduced winter
season flows in several areas, which has reduced available dilution flows for wastewater
treatment facilities in headwater locations.

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Prepared for the Colorado Water Conservation Board, Colorado Department of Natural Resources by
Hydrosphere Resource Consultants, 1002 Walnut Street, Suite 200, Boulder, CO 80302