By Doug Nichols
That is what the trees and shrubs in your yard probably are saying right now. March was supposed to be our snowiest month, but despite the recent spring snowstorms, we are still behind in precipitation. Water has long been a topic of critical interest in Colorado, and the low amounts of snow or rain so far this year make it even more pressing for local homeowners and gardeners.
Here in Berthoud, our municipal water supply comes from the Western Slope (where at least the snowfall was consistently good). It is piped to Carter Lake, and from there to a reservoir where it is treated before heading to our homes. Denver also gets its water from mountain snows, but some metro suburbs are facing a great dilemma as their supplies, which come not from the mountains but from groundwater pumped from wells, are becoming increasingly scarce.
People sometimes visualize groundwater as existing in underground pools or lakes, which deep wells can tap. That is not at all the real situation. Groundwater is present in buried layers of rock called aquifers, where it exists in a manner similar to what it would be like if you filled a bucket with sand and then added water to it.
Furthermore, the aquifers beneath Denver and its suburbs are not great tabular bodies of rock extending throughout the region, as once thought. Recent research is showing that some of Denver’s aquifers are essentially buried alluvial fans with limited geographic extents.
An alluvial fan is like a river delta on dry land and formed at the base of the mountains that existed to the west of the present-day Denver metro area millions of years ago. The aquifers are now buried as much as 760 m (2,500 ft) below the present land surface. They contain finite amounts of water, which have been there for tens of thousands of years. These supplies are rapidly diminishing as municipal pumps work to provide water to homes and lawns.
The problem is especially severe in suburban Douglas County, which throughout the 1990s grew faster than any other county in the nation, and where growth is continuing today. Developers were counting on an unlimited supply of groundwater, but it simply is not there. The direct effects of pumping can be seen in the wells themselves, in which water levels are falling by 20 to 35 feet per year. Existing wells are producing less and less water, so more wells are being drilled to make up the difference. However, it is an un-winnable race, pitting unrestrained growth against geological and hydrological facts.
Perhaps part of the answer for those areas is new reservoirs for surface storage of rain and snowmelt. But then again, all communities on the eastern plains have been experiencing the same abnormally dry weather that we have, so those prospects are not encouraging.
Although we are more fortunate than folks in the south metro area, let us all be careful to use water wisely and conserve what we have.
Doug Nichols was a Scientist Emeritus with the U.S. Geological Survey and a Research Associate with the Denver Museum of Nature & Science. He was a resident of Berthoud. We mourn Doug’s untimely passing in Jan. 2010.
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