CAN THE USEFUL LIFE OF THE DENVER BASIN AQUIFERS BE EXTENDED?

The Denver Basin aquifers represent a large ground water resource along the Front Range of Colorado. It is estimated that approximately 260,000,000 acre-feet of recoverable water is contained in the Denver Basin bedrock aquifers, which cover an approximate 6,700 square-mile area. However, the use of these aquifers is generally concentrated along the Front Range in a relatively small portion of the overall basin.

Currently, it is estimated that there are 300,000 to 400,000 people relying on Denver Basin aquifer water along the Front Range, and water levels are declining in these aquifers at rates of 20 to 30 feet per year. The layering within each aquifer, the bowl-shaped nature of the Denver Basin, and the limited geographic area that each water provider can utilize to install wells all affect the useful life of the Denver Basin aquifers to individual water providers.

In an ideal situation, the Denver Basin aquifers would be reserved for use during dry years, as production from these aquifers is not influenced by drought conditions. In average to wet years, when surface water supplies are more plentiful, renewable water would be used and the Denver Basin aquifer water would be reserved. However, the key is how to achieve this so that the useful life of the Denver Basin aquifers can be extended.

One answer to this question is to develop renewable water. However, the development of new, renewable water supplies is a difficult proposition from an economic, political, and environmental perspective. However, more efficient use of developed renewable water supplies can be achieved through various conjunctive use concepts.

Excess surface water supplies are available from time to time, both during wet years and during wet periods within average years. One methodology is to capture the excess water, treat it, and then inject it into the bedrock aquifers of the Denver Basin. A research project was conducted at the Willows Water District to evaluate issues related to this conjunctive use concept. Another means of conjunctive use is to provide surface storage for the purpose of managing excess surface water supplies. The Parker Water and Sanitation District is currently permitting an off-stream reservoir to maximize the use of surface water supplies, thereby minimizing the need for Denver Basin aquifer water use. Both of these conjunctive use concepts will be discussed.