WSP09428

• File Number: 8449.926
• Description: South Metro Water Supply Study
• State: CO
• Basin: South Platte
• Date: 2/1/2004
• Author: SMWSS Board
• Title: South Metro Water Supply Study
• Water Supply Pro - Doc Type: Publication

The final component of conjunctive use is the existing ground water facilities, i.e., the wells and
infrastructure used to pump and deliver ground water supplies. Most of the water providers meet
their summer peaks through well production. Therefore, many of the wells of each provider are
not used for as much as 9 months each year. The potential exists to use these wells during off-
peak times to act as recharge wells, or to return "borrowed water" to Denver Water, if necessary.

1.6 South Metro Area Planning

This plan of conjunctive use has been the topic of a number of studies by the South Metro water
providers since the early 90's. This work was then expanded through the Metropolitan Water
Supply Investigation ("MWSI") (Reference 1.3) where conjunctive use was reconunended as a
future source of supply for the South Metro Area. This study, completed in 1998, describes the
plan as a viable source of additional renewable water supplies. The MWSI estimated additional
water supplies that might be diverted from the South Platte and Blue River systems at up to
60,000 acre-feet on an average annual basis. The modeling at that point, however, did not
include a detailed modeling of Denver Water's system and water supply. The potential yield of
this project will be evaluated in this study through Denver Water's modeling of the proposal
using their P ACSM model.

The South Metro Area, in pursuing this conjunctive use alternative, requested support by Denver
Water to pursue this concept since the plan is very much dependent upon Denver Water's
existing water supply facilities. Denver Water indicated their willingness to further study this
plan in conjunction with the South Metro water providers, but also reconunended and
encouraged the participation of the Colorado River Water Conservation District since the plan
involved potential additional water supply diversions from the Blue River Basin. Douglas
County Water Resource Authority participants, Denver Water, and the Colorado River Water
Conservation District signed an agreement to jointly fund a cooperative study in March of 1999.
The parties worked together to formulate a scope of work for the study. (Appendix I) The
agreed upon scope of work identifies alternatives to water supply development for the South
Metro Area over a fifty-year period, through the year 2050, as follows.

1.6.1 Alternative lA - This is the Status Quo Alternative - (Future Supplies through Non-
tributary Ground Water). Alternative IA evaluates the buildout of the South Metro Area
based primarily on concentrated development of its non-tributary ground water reserves. This
plan assumes that most of the future development is served through continued development of
non-tributary ground water supplies, with peak demands met through pumping. The plan
includes a component of conservation and aggressive development of reusable supplies.

1.6.2 Alternative IB - This is the Status Quo Alternative with Storage for Peaking -
(Future Supplies through Non-tributary Ground Water with Storage for Peaking).
Alternative 1 B is again the buildout of the South Metro Area based primarily on concentrated
development of its non-tributary ground water reserves. This alternative, however, recognizes
that well-to-well interference during peak pumping periods is significant, and will be reduced by
the year round pumping of wells at an average rate. This will require fewer wells but storage is

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