South Platte River Basin: Groundwater study challenges data that led to the shut down and curtailment of wells

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From The Fencepost (Bill Jackson):

The study was done to try to maximize the use of water in the South Platte River Basin for everyone in the state, said Bob Longenbaugh, who has been in the water business for 50 years. He teamed with Halepaska and Associates, a consulting groundwater engineering firm in Littleton, in a study of the South Platte River groundwater for the Weld County Farm Bureau, the Colorado Corn Growers and other organizations. The study focuses on the importance of groundwater when considering the South Platte as an irrigation source. Logenbaugh said 10.5 million acre-feet of water is in the main stem of the river’s alluvial aquifer — below the surface flow of the river. That’s about eight times the amount that flows down the river annually from snow melt, thunderstorms, return flows, releases from reservoirs and other sources. The study measured irrigation wells along the river and found some of the highest historic water levels ever recorded in the fall of 2009. Those levels have not receded since then…

He said the reduction of well pumping not only limits the return of water to the river, but is probably a factor in high water tables along the river from Brighton to Julesburg. In addition, he said, Colorado lost a tremendous amount of water into Nebraska last year, which continues this year. Between Oct. 1, 2009, and Sept. 30, 2010 — the state designated water year — 610,000 acre-feet of water flowed out of Colorado into Nebraska. From Oct. 1, 2010, to Feb. 28 of this year, another 106,000 acre-feet has left the state on the South Platte, he said. “That’s above what Colorado is required to deliver to Nebraska under the compact. That water belongs to the citizens of Colorado, and Colorado has the right to use that water,” Longenbaugh said…

“(The study) verifies what we have expected for years, that (irrigation) wells don’t have a 50-year depletion of water in the river, and in fact, they recycle and refill annually. That’s why the water tables have come up,” [Bob Winter of Windsor] said. Much of that data has been around since the 1940s, he said, but it’s never been gathered to be analyzed in one place. “We finally have a report with facts, and now there are those who question the facts,” Winter said.

Dick Wolfe is the state engineer and director of the Colorado Division of Water Resources. He said he has reviewed the report completed by Longenbaugh and Halepaska and said there is some misinterpretation of the compact between Colorado and Nebraska. But he agrees with the report that said there is a need for improved management tools.

More South Platte River basin coverage here.

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