Trends in nitrogen and phosphorus concentrations in southern New England streams, 1974-92

Abstract

Trends in concentrations of nitrogen and phosphorus in southern New England streams since the passage of the Clean Water Act of 1972 are similar to National trends with total nitrogen concentrations commonly increasing and total phosphorus concentrations usually decreasing. Decreases in ammonia-nitrogen concentrations were associated with increases in nitrate-nitrogen concentrations and may indicate that improved wastewater treatment has had a beneficial effect on water quality. Increasing concentrations of total nitrogen, however, may contribute to eutrophication in Long Island Sound.

Water quality in the Connecticut, Housatonic, and Thames River basins, Connecticut, Massachusetts, New Hampshire, New York, and Vermont, 1992-95

“…Nitrate concentrations in streams commonly increased during 1980-92, whereas ammonia and total phosphorus concentrations commonly decreased (Zimmerman, 1997). Decreases in ammonia concentrations were generally associated with increases in nitrate concentrations, resulting primarily from improved wastewatertreatment processes, which convert ammonia to nitrate .…”

“…These changes were primarily the result of more effective wastewater treatment, which has significantly improved the water quality in streams over this period (Zimmerman, 1997). …”

Review of Phosphorus Control Measures in the United States and Their Effects on Water Quality

“…Large phosphorus concentrations in a small stream (Prairie Creek) may be due to localized livestock inputs (Boyd, 1996). Total phosphorus concentrations have decreased (1974-92) at 13 of 16 stations (Zimmerman, 1997). Nutrient concentrations are very small; there is some interest in adding nutrients to streams to increase biologic productivity (Steven Frenzel, U.S. Geological Survey, oral commun., 1998).…”

Nutrient sources and loads in the Connecticut, Housatonic, and Thames River basins

“…Streams in highly urban areas are characterized by high concentrations of dissolved solids, high nutrient concentrations, elevated specific conductance, and concentrations of some trace constituents in the parts-per-billion range (Davies and others, 1996). Water-quality conditions and trends have been summarized and interpreted by Healy and others (1994), Healy and Kulp (1995), Zimmerman andothers (1996), and. Nutrient data are available for selected monitoring stations for periods ranging from water years 1970-95 to water years 1 1993-95 (table 2).…”

“…In large drainage basins with a record of 20 years or more, maximum total nitrogen loads are two to three times larger than minimum total nitrogen loads, whereas maximum total phosphorus loads are three to six times larger than minimum total phosphorus loads. This wide range in phosphorus loads probably reflects the downward trend in total phosphorus concentrations in streams over a 20-year period Zimmerman, 1997).…”