<em>Abstract</em>.—Agriculture has been identified as a potential leading source of nutrients (nitrogen and phosphorus) and sediment enrichment of water bodies within the Mississippi River basin (MRB) and contributes to impaired water quality and biological resources in the MRB and the northern Gulf of Mexico (GOM). This study reviewed agriculture, impacts on water quality and biological resources, and a brief introduction of watershed conservation programs in the MRB. Agriculture has increased nutrients and sediment loads to the Mississippi River and the northern GOM since the 1950s. Fish and macroinvertebrate communities have shifted, and low oxygen and high-turbidity-tolerant groups became dominant. In addition to existing conservation practices such as the Conservation Reserve Program through the 1985 farm bill and other related programs (e.g., the Wetlands Reserve Program), a recent basin-wide conservation initiative—the Mississippi River Basin Healthy Watersheds Initiative (MRBI)—was launched by U.S. Department of Agriculture Natural Resources Conservation Service in 2010. The MRBI provides financial incentives (more than US$222 million) to producers and landowners in 640 watersheds of 13 states to implement voluntary conservation practices that improve water quality, restore wetlands, enhance wildlife habitat, and sustain agricultural profitability. Edge-of-field and watershed monitoring have been initiated through the MRBI and related agricultural conservation programs such as Section 319 of the U.S. Environmental Protection Agency Clean Water Act and new initiatives such as the Discovery Farms program in Arkansas, Wisconsin, Minnesota, and North Dakota, Pioneer Farm in Wisconsin, the Louisiana Master Farmer Program in Louisiana, and others in the MRB states. These efforts will greatly improve downstream watershed ecosystem health by avoiding, controlling, and trapping nutrient and sediment runoff from agricultural fields to the Mississippi River and GOM. Although there continues to be problems with nutrient transport, sedimentation, and depleted groundwater supplies, agriculture will likely have less influence on the future ecological health condition of the Mississippi River and GOM. Future restoration programs need to focus more on state or regional coordination by classifying restoration projects and standardizing the geographic scale and evaluation methods across the whole MRB.
Trends in suspended-sediment loads and concentrations in the Mississippi River Basin, 1950–2009
