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

1\1etropolitan Water Supply Investigation

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Vthile each water supply category evaluated in the MWSI appears to present significant,
td,chnically feasible cooperative opportunities, each also raises several issues that present
sl~rious obstacles to implementation without considerable additional work.
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Executive Summary

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~he table below summarizes the MWSI's findings.

Cooperative Supply
Cateoorv Suoolv or Yield Potential Actions Items/Unresolved Issues
Conjunctive Use up to 60,000 acre-feet of South Platte and Blue River stream depletions
surface water yield under Water right constraints
example project analyzed Feasibility of long-term, large scale recharge
IGA's among participants
Balancing groundwater depletions with increased
use of surface waters
Effluent up to 120,000 acre-feet Relatively high costs
of excess reusable return . Public acceptance of potable reuse
flows; specific project yields Effects of exchanges on water quality
were not investioated Effects on inslream flows
Interruptible Supply up to 190,000 acre-feet Would require major institutional changes
of interruptible supply; Impacts to agricultural communities
specific project yields Geographic/cost considerations
were not investioated
Other System up to 20,000 acre-feet Water right constraints
Integration of yield under example IGA's among participants
Onnortunities nroiects analvzed Federal action (Chatfield storaae reallocation)

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COOPERATIVE WATER SUPPLY OPPORTUNITIES

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Coniunctive Use would involve the linkage of groundwater systems currently serving
communities in parts of Douglas and Arapahoe counties with the Denver Water system.
Water available from the Denver system in average and wet years could be used to meet
demands and for recharge of Denver Basin aquifers. Groundwater sources would be used
to meet demands not fully satisfied by surface water sources and during periods of
drought. For the example project analyzed, conjunctive use arrangements could yield up
to 60,000 acre-feet per year to meet new demands or reduce existing groundwater
pumping from the Denver Basin aquifers.

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Conjunctive use presents a promising solution to continued dependence upon non-
renewable groundwater resources by the growing communities in the South metro sub-
region. Conjunctive use also raises several unresolved questions. To the extent that a
conjunctive use project would rely on additional transmountain diversions from existing
facilities and water rights, this would raise objections from West Slope interests.
However, the operational flexibility inherent in a conjunctive use project could allow for
mitigation of some impacts while still generating significant yield. Other issues and
uncertainties associated with conjunctive use include changes in water rights, the
feasibility of large-scale recharge over the long term, and the challenges associated with
securing required intergovernmental cooperation among potential conjunctive use
participants.

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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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