Local water reserves provide hedge against drought

The most recent data available from the U.S. Drought Monitor shows most of southern Colorado experiencing extreme drought conditions.

Extreme drought conditions across much of the Arkansas River Basin prompted Upper Arkansas Water Conservancy District General Manager Terry Scanga to prepare a water supply reliability report for the district’s July board meeting.

Scanga said the district has a “firm annual water supply” of 1,840 acre-feet (600 million gallons) and currently stores 5,700 acre-feet of water (1.86 billion gallons) in various reservoirs.

Annual demand for district water is 1,118 acre-feet, Scanga said, leaving the district with an extra 722 acre-feet (235 million gallons) of water for the year.

Board Chairman Tim Canterbury asked, “How many years of drought before it affects our firm supply?”

Scanga replied, “Even if the district’s annual water supply went to zero, which I can’t imagine happening, we have 4 years of reserves currently in storage.”

As an example of how drought years affect water supplies, Scanga said that, for an average year, one Twin Lakes share yields 0.93 acre-foot of water. During the driest years, the same share has yielded 0.73 acre-foot of water.

Based on that data, drought conditions can reduce annual water supplies by as much as 20 percent, indicating that the district could meet its annual demand for water and maintain reserves for several years.

Scanga’s report also identified three components of demand for district water, with its standard augmentation plan accounting for 628 acre-feet per year. Long-term leases account for 252 acre-feet, and short-term leases account for 237 acre-feet.

If exceptional, long-term drought conditions ever did cause the district to run low on water, Scanga said the district would then suspend short-term leases to reduce demand until supplies could recover.

For additional news and information about the Upper Arkansas Water Conservancy District, visit their website.

Joe Stone