WKU Working To Improve Water Quality At Rough River Lake

March 12, 2007

Bowling Green, Ky. -After a three-year effort from farmers, government and private conservation and agricultural groups, and Western Kentucky University scientists and students, drinking water source quality has improved for several Kentucky communities.    

In 2004 the Hoffman Environmental Research Institute at WKU was awarded a grant from the U.S. Environmental Protection Agency (EPA) to assess atrazine levels in the Rough River Lake watershed, with the goals of helping regional stakeholders reduce contamination levels in the water supply and providing cleaner water for drinking, recreation and wildlife. This effort directly involves growers, professional chemical applicators, and state and federal agencies in Hardin, Grayson and Breckinridge counties.

Atrazine is an herbicide widely used for corn production in Kentucky. It has recently received attention due to concerns over adverse health effects for people and wildlife, and for its potential to contaminate surface water and groundwater. Health and environmental concerns for atrazine include possible disruption of normal reproductive system development in aquatic life, though such effects have not been proven, and it is unclear if or how this may apply to humans.

EPA has also classified atrazine as not likely to be carcinogenic, and recently completed an extensive safety review for atrazine, re-registering it for agricultural use. The maximum contaminant level for drinking water is 3 parts per billion (ppb). This figure is an annual maximum average, and is the level at which EPA believes atrazine will not cause adverse health effects over a person’s lifetime, including a 1000-fold margin of safety.

Standard water treatment procedures may not sufficiently reduce atrazine in drinking water, and its removal is very expensive for small water districts. Therefore, many districts with high atrazine levels find that changing land management practices is the most economical method of improving water quality. Leitchfield Water Works in Grayson County is one such district, and is one of four supply systems with intakes on Rough River Lake. In 2004, atrazine levels in individual samples of treated water at the facility repeatedly rose above the 3 ppb limit, measured up to 4.9 ppb. However, the annual average concentration stayed below the 3 ppb limit.

In response, WKU and the Kentucky Department of Agriculture began extensive sampling throughout the watershed to identify source areas of atrazine pollution and study its movement through the lake. Additionally, state water representatives, county extension agents and local farmers worked to manage farmland in the watershed to reduce atrazine runoff. Educational efforts emphasized the importance of following the atrazine label Precautionary Statement and the benefits of implementing Best Management Practices (BMPs). The label specifies required set-back distances between waterways and atrazine use areas. BMPs may include further suggestions for maximizing effectiveness while minimizing run-off, such as using less total herbicide, but in pre- and post-planting treatments. 

Also, an initiative began to enroll land in the USDA’s Conservation Reserve Program (CRP), which cost-shares in the creation of buffer strips of grass or trees around riparian areas. Buffer strips can dramatically lower field runoff potential for sediments and chemicals into nearby waterways.

Hardin County extension agent Rod Grusy reports, “Local farmers have developed a positive attitude regarding the risk of atrazine movement from application sites to surface and groundwater as a result of local educational efforts.… Implementation of best management practices in target watersheds has increased substantially since the awareness campaign began.”

BMPs are especially important in karst landscapes such as found in the Rough River Lake watershed and large areas in central and western Kentucky. Networks of sinkholes and underground streams allow water and contaminants to flow directly into water supplies without the filtration that results from slow seepage through soil and rocks, meaning Kentucky’s waterways are particularly vulnerable to contamination.

Results from 2005 and 2006 are promising. In 2005 only two sampling dates at Leitchfield Water Works found atrazine levels in raw and treated water over the 3 ppb limit. During 2006, atrazine levels were consistently lower throughout the watershed, and both raw and treated water at Leitchfield stayed well below the limit. 

Researchers are optimistic that the reductions are a result of improved buffering around corn fields, and careful following of the atrazine label’s Precautionary Statement. However, weather plays a significant role in how much atrazine moves into water systems, and is likely one cause of the decreasing atrazine over the last three years.
Atrazine is much less likely to be transferred into water systems if no heavy rains occur shortly after application, and if soils are not initially saturated. Early growing season precipitation in 2004 was above average, with very high rainfall in May. In contrast, 2005 and 2006 were dry years with below average precipitation in May. 

Water monitoring will continue in 2007, as will educational efforts for private and commercial applicators.
               
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For information, contact Priscilla Baker at (270) 745-5201.