Water Well Journal
Issue link: http://read.dmtmag.com/i/592194
"On-farm flooding looks very prom- ising," says professor Helen Dahlke, a hydrology expert with the Department of Land, Air and Water Resources. "We're pleasantly surprised by how quickly water tables have responded to on-farm flooding without damage to crops." In spring 2015, Dahlke's team flooded alfalfa at Bryan-Morris Ranch in Siskiyou County, applying more than twice the irrigation the field normally gets in a year. The field produced more weeds than usual—but otherwise the alfalfa suffered no ill effects. "It was amazing to see how well the land absorbed the water and how quickly the water table rose," says Jim Morris, Bryan-Morris Ranch manager. "That's good news for farming and the environment." Dahlke and her team will test flood- ing on almonds in the Central Valley this winter, looking at plant physiology, infiltration rates, water quality, and costs. They are building on previous re- search involving UC Davis and environ- mental engineers in the Kings River Basin, where up to 75% of diverted floodwater percolated down to aquifers. In that research, scientists flooded pista- chios, alfalfa hay, and wine grapes. California is in chronic groundwater overdraft—there is more water being pumped from the ground than filtering in. In wet years gravity helps refill aquifers as land absorbs water from rain, rivers, and snowmelt. In dry years several water districts help that along by diverting excess water during storms and flood releases into infiltration basins, confined areas of sandy soil. But land dedicated to infiltration is scarce. Can California's farmland be called into service? There's a lot to consider, Dahlke says. Not all soils are particularly per- meable, and not all crops can tolerate extra irrigation in the winter. Some soils are especially salty, and some crops need more nitrogen than others. Researchers wonder whether flood- ing fertilized farmland or saline soil will leach those chemicals into the ground- water. Or, could on-farm flooding actu- ally improve groundwater quality by diluting salts and nitrates? Soil expert Anthony O'Geen, who is with the UC Davis Department of Land, Air and Water Resources, recently con- cluded in the journal California Agricul- ture that some 3.6 million acres of farmland have good recharge potential because they could likely accommodate deep percolation with little risk of crop damage or groundwater contamination. Pears, wine grapes, many annual crops, and some varieties of almonds, peaches, and plums appear best suited for on- farm flooding, the team found. "Alfalfa might also be an ideal crop for groundwater banking because it requires little or no nitrogen fertilizer," O'Geen adds. FMCSA Announces More Delays on Final Electronic Logging Device Rule W ith its deadline for releasing a final rule on electronic logging devices approaching, the Federal Motor Carrier Safety Administration announced another delay, pushing anticipated release of a final rule to November 30. The latest announcement is part of several delays as the FMSCA works to handle the coordination and administra- tion necessary in implementing the final rule, which will likely be met with some controversy. The final rule would require paper logging for truckers' hours of service to be replaced by electronic logging devices. NGWA filed comments on the proposed rule, which was released in March 2014. The final rule could increase costs on those businesses that operate fleets of vehicles—given the mandate to convert to electronic logging devices. Study Explores Groundwater and Geothermal Energy in Drought Areas of the West A new study now underway by the U.S. Geological Survey is exploring the groundwater resources and geothermal energy potential in drought-stricken areas of eastern Oregon and nearby parts of California, Idaho, and Nevada. Volcanoes are associated with vast amounts of geothermal energy and lava flows from many of the Pacific Northwest's most important aquifers— potentially the only reliable source of high-quality water during periods of drought. "The research encompasses large areas that have been under drought conditions for several years and data acquired by the study will aid water managers in their efforts to meet the needs of water users in these areas," says Erick Burns, USGS scientist and project chief for this study. The study assesses the groundwater resources and geothermal energy poten- tial within parts of the Northwest Vol- canic Province. This region of the inland Pacific Northwest has been heavily in- fluenced by landscape-shaping volcanic eruptions over the past 17 million years. "Previous assessments have identi- fied this region as having high potential for geothermal development, but large portions of the region have yet to be characterized in detail," says Jonathan Glen, USGS Geothermal Project Chief. "The current study seeks to advance the understanding of where geothermal heat may be efficiently utilized." Groundwater is integral to geother- mal energy production and the study will collect additional information on the groundwater resources in the North- west Volcanic Aquifer system. Much of the region is semi-arid with few large streams, which leads to considerable de- pendence on groundwater for irrigation and public water supplies. Potential impacts from groundwater and geothermal development affect not only water users, but also the ground- water-dependent ecosystems that occur throughout much of the area. The study aims to compile critical information that will aid water managers in balancing the demand and impact from future development. The first study results, summarizing estimates of groundwater quantity by sub-region, are expected for publication near the end of 2016. The study is being conducted in cooperation with the Oregon Water Resources Department, the Idaho Department of Water Resources, and the California Department of Water Resources. To learn more about the study, visit the Joint Groundwater and Energy Study website at or.water.usgs.gov/ proj/geothermal/index.html. NEWS from page 16 18 November 2015 WWJ waterwelljournal.com