In the contiguous United States there are approximately 5 million kilometers of streams and rivers, which contain a diversity of aquatic species including microbes, aquatic vegetation (algae and plants), invertebrates, and fish, all of which play key roles in structuring the food web that sustains aquatic life, wildlife, and in some cases humans. Over the last 50 years, human actions have profoundly altered the natural input and cycling of nutrients (nitrogen and phosphorus) through the environment and greatly increased the amount of nutrients transported to our streams, rivers, and estuaries. Although nutrients are essential for a healthy aquatic ecosystem, excess nutrients can affect aquatic and human health. Impacts to aquatic health include nuisance and toxic algal blooms, oxygen depletion, loss of important instream habitat, and shifts in aquatic food resources. Excess nitrogen in streams also can increase drinking water treatment costs. Excess nutrients have a significant economic impact—causing an estimated $2.2 billion per year in damages related to recreational water usage, waterfront real estate, and drinking water treatment. The increased need for understanding nutrient issues gave rise to the U.S. Geological Survey (USGS) beginning a study to address nutrients and their ecological effects in agricultural streams. Streams in agricultural landscapes have some of the highest levels of nitrogen and phosphorus, resulting in concerns for both stream health and downstream receiving waters. The USGS initiated a study to assess nutrients and their related ecological effects in agricultural streams in eight agriculturally influenced areas across the nation that encompasses a diversity of agricultural practices and environmental settings. The studies were done in the Central Columbia-Yakima River in eastern Washington (Columbia Plateau); the Upper Snake River Basin (Snake River) of southeastern Idaho and northeastern Nevada; Central Nebraska; the Ozark Highlands in Arkansas, Missouri, and Oklahoma (Ozarks); the Upper Mississippi River Basins in Minnesota and Wisconsin (Upper Mississippi); the White River and Great and Little Miami River Basins of Indiana and Ohio (White-Miami); the Delmarva Peninsula (Delmarva); and the Georgia Coastal Plain (Georgia Coastal) that also includes part of Alabama.
These data accompany Munn, M.D., Frey, J.W., Tesoriero, A.J., Black, R.W., Duff, J.H., Lee, Kathy, Maret, T.R., Mebane, C.A., Waite, I.R., and Zelt, R.B., 2018, The quality of our Nation’s water—Understanding the influence of nutrients on stream ecosystems in agricultural landscapes: U.S. Geological Survey Circular 1437, 79 p., https://doi.org/10.3133/cir1437.