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

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period", Borrowing would be subject to a limit based upon the systems' ability to repay
Denver within the specified payback period,

A simple model of these types of conjunctive use arrangements was developed during
Phase II of the MWSI. This model used estimates of Denver's unused divertible supplies
obtained from Denver's earlier modeling studies done as a part ofthe Two Forks EIS, as
discussed previously, The model was used to initially explore the operational dynamics
of a large-scale conjunctive use plan and to generally determine whether a conjunctive
use approach could be effectively used to develop new water supplies and extend Denver
Basin aquifer life. Potential yield, net effects on aquifer storage levels, and relationships
between critical operational and facilities variables were explored, Based on the model
results, conceptual costs for an example large-scale conjunctive use project combined
with a regional treated water delivery system were developed to determine whether such a
concept was within the realm of basic feasibility. The MWSI's Phase II analyses of
conjunctive use are discussed in detail in the MWSI Phase II (;onjunctive Use Summary
Report

A more detailed investigation of the operational and yield aspects of conjunctive use is
being conducted in the Southern Regional Cooperative Action Study (SRCAS). This
study is using more recent estimates of Denver' s unused divertible supplies and is
simulating the potential operations of Denver's reservoirs in a more detailed marmer,
While this study has explored the operational possibilities of conjunctive use in more
detail, several dimensions of feasibility, including water rights, environmental impacts,
institutional arrangements and costs remain to be examined.

More refined analysis will be required to meaningfully determine the feasibility, yield
potential and operating rules of any specific conjunctive use plan. Significant technical,
legal, institutional and environmental issues remain to be addressed, The reader is
referred to Section 3,2,1.7, Issues and Concerns for a discussion of these issues.

3.2.1.6. Results of Conjunctive Use Investigations

CAVEAT: It should be noted that the study results presented and discussed below are
preliminary and conceptual in nature.

MWSI Phase /I Analvsis

The MWSI's Phase II analysis focused on conjunctive use options ''with borrowing," and
explored the sensitivity of yield results to varying rates of aquifer recharge capability, and
surface water borrowing limits, Alternate sets of runs were made to maximize surface
water capture assuming either: 1) no net depletion of the groundwater aquifers; or 2) a
300-year aquifer life (i,e. an average armual net depletion of one-three hundredth (l/300th)
of the groundwater available beneath the service areas of participating groundwater
providers,

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