Manure Storage Systems Impact Groundwater Ground Water Monitoring and Assessment Program Report Summary published by the Minnesota Pollution Control Agency April 2001 Results from our studies indicate manure storage systems impact ground water. In our study using temporary wells at sites older than five years, we observed plumes down-gradient of all manure storage systems. Impacts were greatest at sites where manure was stored in basins lacking a constructed liner. Plumes extended several hundred feet at all sites except those with a concrete liner. Plumes at sites with concrete-lined systems were limited to distances of about 100 feet from the manure storage basin. Plumes were typically characterized by high concentrations of ammonia, organic nitrogen, phosphorus, organic carbon, potassium, and chloride. Concentrations of ammonia and phosphorus represent potential concerns for surface water intersecting a plume. Ammonia and phosphorus attenuated within plumes, however, and were generally below levels of concern 200 feet down-gradient of the manure basin. At two sites having earthen liners underlain by a thick unsaturated zone, plumes were characterized by high nitrate concentrations. Nitrate is slowly attenuated in ground water. A 200 foot setback distance from a well may not be protective for earthen-lined systems underlain by a thick, coarse-textured vadose zone. Back to Main Index Page