Beneath ground lies treasure

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BY KRISTINE NEMEC / For the Lincoln Journal Star

For decades, water has been diverted from the Platte River into more than 500 miles of canals and pipelines to irrigate thousands of acres of crops in south-central Nebraska.

  But for the first time in its 64-year history, the Central Nebraska Public Power and Irrigation District will reduce the amount of surface water delivered to farmers this year. The district also will shorten by four weeks the irrigation season, which usually runs from late June to early September.

  The reason: Lake McConaughy, from which water flows through the district’s canals, has shrunk to about a third of its maximum capacity since the drought began five years ago.

  Central may be hurting for surface water, but a wealth of groundwater lies beneath much of the district’s five-county irrigated area. (CORRECTION NOTE: mound underlies three south-central counties.) This so-called “groundwater mound” is symbolic of the state’s new efforts to manage groundwater and surface water as one resource.

  Since Central’s irrigation canals began drawing surface water from  McConaughy in the early 1940s, the groundwater table in parts of Gosper,  Phelps, and Kearney counties has risen by more than 50 feet, said Mark   Burbach, assistant geoscientist with the University of Nebraska-Lincoln.

  “We saw it beginning about a decade after the project began,” he said.

  Burbach said the majority of this water came from leakage from canals. In recent years, Central has reduced the leakage by lining its canals and converting some to pipelines.

  According to Burbach, the amount of water in the mound is equal to four or five full-capacity Lake McConaughys. At full capacity, McConaughy holds 1.75 million acre feet, according to statistics from Central.  An acre foot is the amount of water it takes to cover one acre one foot deep; 1.75 million acre feet would cover Nebraska with 1/8 inch of water.

  So, if the mound holds four to five as much water as McConaughy, that means it could hold nearly 8 million acre feet, which would cover the entire state with water about ½ inches deep.

  Many of Central’s customers tap into that resource. Jeff Buettner, Central’s information and communications officer, said 60 percent to 70 percent of Central’s surface water irrigators also have groundwater wells.

  Farmers with both types of irrigation have an advantage during droughts. In a typical year, Central delivers 15 to 18 inches of water to its surface-water customers, but farmers have had no limits on how much they use. Even though the drought has led Central to reduce allocations by two-thirds, the district is trying to help its customers get enough water.

  “You can’t grow a normal yield with 6.7 inches of water,” said Dudley Nelson, who sits on Central’s board and grows corn and soybeans in Kearney County. “But farmers who also have groundwater irrigation can transfer their allotted surface water to those who only use surface-water irrigation. This will help everyone get close to normal yields.”

  This is the first year the district has used a transfer program.

  “There is not a lot of concern among farmers about the transfer program,”  Nelson said. “Everybody had the opportunity to get extra wells.”

  However, farmers west of U.S. 183, which runs through Holdredge, are an   exception. Under the state’s new water law, LB962, the Nebraska Department of Natural Resources determined the area including the groundwater mound west of U.S. 183 is over appropriated, meaning the demand for water exceeds the amount available.

  Last September, the department banned drilling new wells in that area. Yet the groundwater mound extends well east of U.S. 183.

  Ann Bleed, deputy director of the Natural Resources Department, said that even with the mound, the effects of increasing water use exceed the groundwater supply.

  “The mound is like a tributary,” she said. “It provides water to the Platte River and the Republican River. If more of the groundwater is used, there will be less water in the rivers.”

  Her answer reflects the state’s new policy for managing groundwater and surface water together.

  Last winter, Central asked the department whether the ban on new wells  could be lifted.

  “Our project put the water there,” Buettner said. “So, as a matter of equity, our customers should be allowed to use groundwater from it.”

  In January, the department said farmers in the overappropriated areas could drill wells if they offset the wells, or retired a water use to make up for the new water they will be using. For example, a farmer could offset a new well by not irrigating a portion of his or her crop and turning it into pasture.

  Jason Lavene, who grows corn and soybeans west of U.S. 183 in Gosper County, is disappointed by the well moratorium.

  “I had planned on putting in new wells,” he said. “Now I have to spend more money out of my pocket on bringing in surface water.”

  But Lavene thinks the transfer program will help. He said a lot of farmers were switching to shorter-season corn and soybeans that need less water than many varieties.

  Farmers aren’t the only ones interested in the groundwater mound.  Conservationists would like to divert some of its water to the Platte River to  benefit wildlife.

  Duane Hovorka, executive director of the Nebraska Wildlife Federation, is a member of a committee preparing a program to improve and conserve habitat for four threatened and endangered Platte River wildlife species in Nebraska.   The plan is required as part of an agreement among Nebraska, Colorado, Wyoming and the U.S. Department of the Interior to address habitat and water issues in the Platte River basin.

  Rather than continue to let the groundwater mound rise, Hovorka said, the committee would like to pump out some of the surplus water with high-capacity wells. That extra water would be pumped into tributaries of the Platte during dry periods to supplement flows for wildlife on the river.

  The groundwater mound already benefits farmers and wildlife to some extent.

  “The groundwater table is so high in some areas that cornfields are irrigated from below,” said Hovorka. “The mound also recharges wet meadows and wetlands. We would have to be careful so we don’t pump out too much water and dry out the fields and meadows.”

  If done correctly, Hovorka believes the plan would benefit wildlife during times of drought.

  Kristine Nemec is an ecologist with the U.S. Army Corps of Engineers in Omaha. She is also a student in the science-writing class at the University of Nebraska-Lincoln College of Journalism and Mass Communications.

In the months ahead

  “Platte River Odyssey” is a collaboration between the Lincoln Journal Star and the University of Nebraska-Lincoln College of Journalism and Mass  Communications. In the coming months, the series will deal with many themes related to the Platte River basin. They include:

  * Big Mac dries up

  * The economics of irrigation

  * History of irrigation in the Platte Valley

  * Litigation over water in the Platte basin

  * The Platte Metroplex—Lincoln and Omaha rely on the Platte

  * Recreation on the Platte