Arkansas Basin ag water changed to other uses at twice the rate of Colorado as a whole

Flood irrigation in the Arkansas Valley via Greg Hobbs
Flood irrigation in the Arkansas Valley via Greg Hobbs

From The Pueblo Cheiftain (Chris Woodka):

Water use for irrigated agriculture in the Lower Arkansas Valley has dwindled at nearly twice the pace for Colorado as a whole over the past 25 years. That information comes from a report issued last week by the U.S. Geological Survey that gives a snapshot of water use in the nation as of 2010.

“It’s a shame that we’ve lost so much farmland in the Arkansas basin,” said Jay Winner, general manager of the Lower Arkansas Valley Water Conservancy District, which formed in 2002 to protect water resources. “Our friends in El Paso County and Aurora need to understand the value of agriculture to this basin. We can’t become dependent on foreign food the way we have with foreign oil.”

The report looks at diversions of streams and groundwater pumping at five-year intervals throughout the United States. It also includes links to data since 1985 that track how water is being used at the county level. Those data show that irrigation water used in Bent, Crowley, Otero, Prowers and Pueblo counties — the primary irrigated farming area of the Arkansas Valley — fell by 35.5 percent. The statewide rate fell 21.7 percent over the 25-year period.

Two factors were at work:

  • The sales of agricultural water rights to Colorado Springs, Aurora and Pueblo decreased irrigation, particularly in Crowley County, where diversions fell to 8.4 million gallons per day (mg/d) from 114 mg/d in 1985.
  • New state well regulations that require replacement of water that is pumped with water from surface sources. In Prowers County, total diversions from both sources were 144 mg/d, down from 445 mg/d in 1985.
  • Bent County irrigation water plummeted by more than 50 percent during the 25-year period, dropping to 134 mg/d from 339 mg/d. Water use held steady in Pueblo and Otero counties, fluctuating along the lines of relative precipitation.

    “A lot of the decrease in Prowers and Bent counties goes back to the Kansas v. Colorado decision,” Winner said. “We need to have more science behind the discussion in the future.”

    Statewide, water withdrawals and use decreased by 20 percent, dropping to 12.3 million acre-feet withdrawn and 11 million acre-feet used in 2010, compared with 15.3 million acrefeet withdrawn and 13.6 million acre-feet used in 2005. (One acre-foot is 325,851 gallons.) Nationally, there was a 13 percent drop in water withdrawals during the five-year period.

    In Colorado in 2010, 88 percent of diverted water was used for irrigation, compared with 90.4 percent in 2005. The share of municipal water shifted upward to 8 percent in 2010 from 6.6 percent in 2005. Most of the rest was used for power generation.

    The proportion of groundwater dropped to 12 percent in 2010 from 16 percent in 2005, probably reflecting a state decision to shut down wells in the South Platte basin.

    More Arkansas River Basin coverage here.

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