MASGC Project Impacts

Low-grade weirs treat more than 12,500 acres, remove 45 percent of nitrate-nitrogen from water


Non-point source nutrient loading from agricultural sources can result in coastal hypoxia. Innovative best management practices need to be developed and evaluated to enhance nutrient management at this source and ultimately improve water quality throughout the watershed including coastal regions.


Scientists evaluated the ability of low-grade weirs to reduce nitrate-nitrogen experimentally and from a field demonstration standpoint.


Both experimental and field results highlighted greater than 45-percent reductions in nitrate-nitrogen from runoff and identified best management practices (BMP) for using low-grade weirs. Additional benefits from the low-grade weirs include better drainage to farms and retention of four times more sediment than systems that did not have weirs. From 2010-2015 a total of 13,058 acres of surface drainage are being controlled and treated through the use of approximately 68 low-grade weirs. Finally, the MASGC-supported low-grade weir research helped launch a large, multifaceted research and outreach program called REACH ( that now develops, tests and shares additional water quality BMPs and solutions to improve land management throughout the region.


Low-grade weirs developed and tested through MASGC support are managing 13,058 acres of surface water run-off and serve as innovative BMPs that consistently decrease base-flow and storm-flow nitrate-N levels by greater than 45% and retain four times more sediment than non-weir systems, which improves water quality throughout the watershed and in coastal regions. (2014)