Concentrations of phosphorus and nitrogen have generally declined since 1980 in streams draining into the Albemarle and Pamlico Sounds in North Carolina but remain high enough to cause water-quality problems in the Neuse and Tar-Pamlico Rivers, according to the results of a 5-year investigation by the U.S. Geological Survey (USGS). These findings are consistent with recent public concerns about Pfiesteria, fishkills, algal growths, and pollutants in these two river basins.
A recently published USGS report indicates that concentrations of phosphorus and nitrogen in the Neuse River and Tar River exceed water-quality guidelines that were established by the U.S. Environmental Protection Agency in the 1960's. The report summarizes results of 5 years of study and 3 years of data collection as part of the USGS's National Water-Quality Assessment (NAWQA [pronounced nawkwa]) Program.
"Although the water-quality guidelines have been around for many years, they remain relevant by providing some important clues as to why these two rivers seem to have more than their share of water-quality problems," said Tim Spruill, a hydrologist with the USGS. According to the report, a 50-percent reduction in summertime nitrogen and phosphorus concentrations in the Neuse River and a 30-percent reduction in the Tar River and Contentnea Creek (a tributary of the Neuse River) might be necessary to attain the water-quality guidelines. "Mid- to late summer is usually when fishkills and nuisance algal blooms occur in rivers and estuaries because environmental conditions are more favorable for rapid algal growths at this time," said Spruill. When algae deplete the nutrients and begin to die, the decomposing cells deplete the oxygen in water. This lack of oxygen often results in the death of fish and other organisms.
Although nutrient concentrations in the Tar and Neuse Rivers in recent
years have been linked to agricultural, urban, and industrial sources,
Contact: Gerald L. Ryan
United States Geological Survey