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

water provider's boundaries, and greater levels of reuse through extended capture of reusable
supplies.

For example, the ECCV is currently increasing its supply through the importation of Arapahoe
and Laramie-Fox Hills waters purchased from the Willows Water District and located
approximately ten miles from their District. ACWW A and Cottonwood are currently pursuing a
potential plan for indirect potable reuse, which would greatly expand their capability to reuse
their water supplies.

As such, the South Metro Area is already reaching the point where continued development of
available water supplies to meet increasing demands is difficult. At the same time, the
population of the South Metro Area is expected to double over the next twenty years. Unless
other sources of supply can be identified and developed, the South Metro Area will have to meet
these demands through very concentrated development of its non-tributary ground water
supplies.

Since the denial of the Two Forks pennit in 1989, the water providers have been evaluating the
non-tributary ground water as a resource that can be utilized to meet its development needs. The
water providers recognize that concentrated development and mining of the resource will result
in diminishment of the water providers' abilities to pump this water. There have been many
disagreements over the length of time that this supply may be available as a viable resource.
However, the conclusions are that the ability to produce non-tributary ground water is limited,
and that other water supply solutions are necessary in the future. On the other hand, the water
providers recognize the tremendous value of this large ground water reserve that should be used
prudently with proper stewardship. For many years, the study participants have considered the
value in the ground water supply as the ability to conjunctively utilize this water supply to
leverage and increase the availability of renewable surface supplies from surface water sources.
Therefore, for many years these water providers have been pursuing the concept of conjunctive
use.

1.5 Conjunctive Use

The South Metro Area water providers have defined conjunctive use as the following.
Con;unctive Use: The coordinated use of surface water and ground water resources and
facilities to produce a larger, more reliable, and cost effective combined water supply than
could be generated from either source alone.

The first component of conjunctive use is the ground water resource described above. While an
excellent source of water supply, over-development will reduce the viability of the supply.
Therefore, the objective under a conjunctive use plan is to reduce reliance on this resource.

Tributary surface water supplies produce highly variable volumes of water supply each year.
Figure 1.4 shows the annual water supply in the South Platte River Basin over a 44-year period
of record and Figure 1.5 presents similar infonnation for the Blue River Basin. These figures
show the high variability above and below the average water supply yield over that time period.
With the very significant water supply development in these basins to date, the use or diversion

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