Photo: Dan Rahn The DNR figures its nearly 20,000 agricultural water use permits closely reflect thenumber of irrigation systems out there.”Agriculture is the second-largest user of water statewide,” McLemore said. “It’s the single largest user of groundwater.” Nobody knows how much water Georgia farmers pumped into their fields over the drysummer of ’99 — or, for that matter, over any summer.”We can make some educated guesses,” said State Geologist Bill McLemore ofthe Georgia Geologic Survey, a branch of the Environmental Protection Division of thestate Department of Natural Resources. “But there’s no question that’s the weak spotin our water use information system.”With demands on water resources mounting, it’s a weakness the state can’t afford tocarry into the next millennium. So the DNR is funding a University of Georgia projectcalled Ag Water PUMPING (Potential Use and Management Program in Georgia).Agricultural Water Use HighIndustries and cities meter their water use, McLemore said. That allows for fairlyaccurate accounting. Farmers, though, don’t keep track of the water they use. Photo: Dan Rahn County Extension Service agents like David Curry (right) of Toombs County work with local farmers who volunteer to participate in the UGA study. Here, former ag engineer Tony Tyson installs an hour meter to enable technicians to monitor this irrigation system. Farmers water during the growing season. For their biggest crops, that’s about sixmonths. “For that period, they may be the biggest water user overall,” he said.”Some big farms use as much water as medium-size cities.”Ag Water PUMPINGThe need to measure ag water use was clear by the mid-’90s, McLemore said. So the stateasked the UGA College of Agricultural and Environmental Sciences to devise a project tomonitor a statistical sample of the irrigation systems.”The U.S. Geological Survey had tried to get farmers to volunteer in a projectlike this,” he said. But the USGS approach didn’t get the needed data. “USGS hasgood planners in Atlanta. But doesn’t have a local presence close to the farmers.”The CAES, through its Extension Service, does. Agents in every county work daily withfarmers and have close links with CAES engineers and other scientists.Monitoring 400-plus Irrigation Systems”We put together a proposal to measure 400-plus systems across the state over fiveyears and develop (computer) models to accurately estimate total water use,” said UGAengineer Dan Thomas.Thomas, a CAES professor of biological and agricultural engineering, heads a UGA teamthat began setting up the monitoring system this summer. UGA technician Jason Mallard checks the flow rate on a southeast Georgia center pivot rig, one of the 400-plus irrigation systems to be monitored over the next five years. This story is another in a weekly series called “Planting the Seed: Science for the New Millennium.” These stories feature ideas and advances in agricultural and environmental sciences with implications for the future. Using the state permits, the team came up with a sample of irrigation systems tomonitor. They work through county agents to contact each farmer on the list.Farmers Take Part VoluntarilyTo include an irrigation system in the study, UGA engineers and technicians first checkits water flow rate. If the rig doesn’t already have an hour meter, the team installs one.Then technicians will check the meter monthly to see how long it pumped.The project still requires farmers to volunteer. But so far, that hasn’t been aproblem. “Most of our farmers understand the need for this study,” said DavidCurry, an Extension agent in Toombs County.Thomas said getting the monitoring part of the project in place will take two years.”About 170 systems are completed now,” he said. “We have three groups, andat times four, doing the installation.”Southwest, Southeast Areas FirstWater disputes in southwest Georgia and saltwater intrusion in groundwater along thecoast make water-use data from those areas more critical. They were the first areas to beincluded, Thomas said.The work will soon expand. In 2000, the team will not only put in the rest of themonitoring sites, but will start checking the ones already installed.As the data begins to flow, the work on the computer models will grow. The models willprovide accurate water-use data on many levels — by county, drainage basin, etc.”Statewide, we’ve got pretty reasonable water-use estimates now,” he said.”This will give us more precise data in local areas.”That data, McLemore said, is essential. “Natural resource management is based ongood science and good engineering,” he said. “And those depend on accuratenumbers.”For more information on the project, contact Thomas or research coordinator CathyMyers-Roche at (912) 386-3377 or agricultural engineer KerryHarrison at (912) 386-3442.