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

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Metropolitan Water Supply Investigation

MWSI Results

The results of the Phase II modeling showed a potential yield of up to 60,000 acre-feet
could be attained annually from a conjunctive use arrangement with no net depletion of
the aquifer. This yield increased to 73,000 acre-feet assuming that a 300-year aquifer life
could be tolerated,

The following assumptions were made in these Phase II analyses,

· All of Denver's estimated 85,000 acre-feet of unused divertible supplies (including
Blue River, South Platte and Moffat supplies) were treated as a single inflow to
Denver's system, available for conjunctive use, divertible at Strontia Springs and
storable in Denver's reservoirs.

· All of Denver existing raw storage (505,000 acre-feet) was treated as a single
reservoir, available for borrowing and capable of capturing Denver's unused
divertible supplies,

· A borrowing storage trigger of200,000 acre-feet (Denver's total storage level
below which borrowing is suspended).

. A borrowing limit of 100,000 acre-feet

· DCWRA providers' combined wen pumping capacity of 9,000 acre-feet per month
(equal to peak month demand for 60,000 AF per year),

· Well recharge capacity of 4,500 acre-feet per month (equal to 50% of well
pumping capacity) is feasible over the long term.

. A new 12,000 acre-feet peaking reservoir in Douglas County.

· A new pipeline of unlimited capacity from Conduit 26 to DCWRA providers,

Under the simplifYing assumptions made in this Phase II analysis, the results suggested
that conjunctive use could be a source of significant new yield, The important roles of
aquifer recharge and of borrowing-pay back arrangements with Denver's surface
reservoirs in capturing additional surface supplies became obvious. The results of the
Phase II studies were sufficiently positive to warrant further investigation, which is
occurring in the Southern Regional Cooperative Action Study (SRCAS),

Southern Reaional CooDerative Action StudY

The conjunctive use analyses undertaken in the SRCAS relied on a more detailed model
and more refined assumptions and data regarding Denver's unused divertible supplies,
surface water reservoirs available for borrowing and facility capacities, The model
included a more detailed representation of Denver's upper South Platte and Blue River
systems and DCWRA providers, Cheesman, Dillon and Eleven-Mile reservoirs were
modeled separately and were considered as the only Denver reservoirs available for
potential inclusion in a conjunctive use plan. Daily estimates were obtained of Denver' s
unused Blue River and South Platte divertible supplies under Denver's Near-Term water
use scenario. These supplies were split into those portions occurring tributary to Dillon,
Cheesman, Eleven Mile, and Strontia Springs. Model runs explicitly reflected capacity
constraints for all new and existing pipelines and reservoirs in the system,

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Prepared for the Colorado Water Conservation Board, Colorado Department of Natural Resources by
Hydrosphere Resource Consultants, 100:2 Walnut Street, Suite 200, Boulder. CO 80302