Importance of Nitrogen Deposition to Freshwater Streams in the US.
Randy Waite1, Ginger Tennant2, Tara Greaver3, Michele Eddy4, Benjamin Lord5, Samuel Kovach6 and Marion Deerhake7
This poster describes a coarse scale data compilation and analysis of nitrogen loads to freshwater bodies in select states to examine where atmospheric nitrogen deposition is sufficient to surpass tipping points that exceed nitrogen water quality criteria for individual waterbodies. The goal of this project is to identify locations throughout the country where a reduction in atmospheric nitrogen deposition might improve water quality conditions from an impaired to a recovered state. In locations where a reduction in atmospheric nitrogen deposition is predicted to mitigate impairment, the necessary load reduction is expressed as an estimated percent of the long-term atmospheric nitrogen deposition loading estimated for the site from existing data. This analysis utilizes sites sampled during the National River and Streams Assessment (NRSA). Data on each NRSA site were gathered that identified the dominant nitrogen source, any intersecting impaired waters, and applicable water quality criteria. Calculations were also performed on the water chemistry information collected for each site to determine whether the site is nitrogen-limited, phosphorus-limited, or co-limited.
1U.S. EPA, OAR, OAQPS, waite.randy@epa.gov
2U.S. EPA, OAR, OAQPS, tennant.ginger@epa.gov
3U.S. EPA, ORD, NCEA, greaver.tara@epa.gov
4RTI International, mceddy@rti.org
5RTI International, blord@rti.org
6RTI, skovach@rti.org
7RTI International, med@rti.org