Some related background material:
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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, the report presents evidence that natural geologic sources of phosphorus increase the problem in these two basins. Based on analysis of ground-water and stream samples from areas throughout the Coastal Plain, ground water that empties into streams in some parts of the basins contains high concentrations of phosphorus. Phosphorus in ground water discharging to streams of the Neuse and Tar River Basins is often 0.2 part per million (ppm) or more. Based on published guidelines, streams draining directly into ponds, lakes, or estuaries should have phosphorus concentrations less than 0.05 ppm to prevent nuisance algal growths.
Relative to 19 other basins studied as part of the USGS NAWQA Program across the United States, the Tar and Neuse River Basins have some of the highest (upper 25 percent) nutrient concentrations observed. In general, highest concentrations of nutrients occurred in agricultural and urban streams.
Other findings from the report include:
Copies of USGS Circular 1157, "Water quality in the Albemarle-Pamlico Drainage Basin, North Carolina and Virginia, 1992-95," by Timothy B. Spruill, Douglas A. Harned, Peter M. Ruhl, Jo Leslie Eimers, Gerard McMahon, Kelly E. Smith, David R. Galleone, and Michael D. Woodside are available, free of charge, from the USGS Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, (303) 202-4700 (fax requests to (303) 202-4693); or from the U.S. Geological Survey, 3916 Sunset Ridge Road, Raleigh, NC 27607. A copy of the report may be viewed on the World Wide Web at the following URL: http://water.usgs.gov/lookup/g et?circ1157/. click here for link *** USGS ***
[For additional technical information, contact Tim Spruill, Project Chief, Albemarle-Pamlico NAWQA, 919-571-4088, or send email to tspruill@usgs.gov].
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Although agriculture and urban activities have substantially affected water quality in several areas of the South Platte River Basin, concentrations of pesticides and volatile organic chemicals (VOCs), such as MTBE, are generally below levels of concern for human health, according to the results of a 5-year investigation of water quality by the U.S. Geological Survey.
This study was among the first 20 studies conducted by the USGS as part of the National Water-Quality Assessment (NAWQA) Program to determine the status and trends, and understand the natural and human factors that affect water-quality conditions across the nation.
"From the standpoint of human health in agricultural areas, we were most concerned about nitrate and pesticides in local drinking water," said Kevin Dennehy, USGS hydrologist in charge of the study. "While we found pesticides in 29 out of the 30 wells sampled, the concentrations were low throughout the agricultural land use area, and concentrations generally were below the regulatory criteria for each of the individual pesticides."
Surface- and ground-water resources in the Denver metropolitan area are susceptible to contamination from pesticides and VOCs. All surface-water samples collected at two urban sites contained at least one pesticide, and water from 90 percent of the wells in the shallow alluvial aquifer contained at least one pesticide. VOCs were detected in 86 percent of the wells sampled from the shallow alluvial aquifer. Sixty-two percent of the samples had more than one VOC present.
The most frequently detected VOC was methyl tert-butyl ether (MTBE), a gasoline additive used to reduce carbon monoxide emissions from vehicles during winter. Although pesticide and VOC concentrations generally were small, their widespread occurrence is a concern. Currently, neither surface nor ground water from the urban area is used for drinking water, but better management of potentially toxic substances may be needed to protect water resources for possible future use as a drinking-water supply.
The good news from the USGS report is that surface and ground water in the forested mountain areas are generally of good quality and relatively unaffected by humans. Mining activities and residential development, however, have impacted water resources and fish communities. Wells are the primary drinking-water source for most mountain communities, but pesticides were not detected in well water, and only one well had a nitrate concentration above the U.S. Environmental Protection Agency drinking-water standard.
VOCs, such as gasoline components and cleaning solvents were detected in 30 percent of the wells sampled in the mountain areas, but none of the concentrations exceeded drinking-water standards. The occurrence of VOCs in mountain wells indicates that ground water is susceptible to contamination from development and other human activities on the surface.
"Downstream from Denver, ground water is less of an option as a rural drinking-water supply because of the impacts to ground-water quality from the intensive application of agricultural fertilizers and manure, accompanied by widespread irrigation," Dennehy said. "We found that nitrate concentrations exceeded the maximum contaminant level, or MCL, in about 48 percent of agricultural wells sampled. (A maximum contaminant level [MCL] is a drinking-water regulatory standard that is set by the USEPA. Although the wells sampled for this study were not drinking-water wells, local residents get their drinking water from domestic wells that tap the same underground water-supply source," Dennehy said.
"A complicating factor in telling a complete story about water quality in the basin," Dennehy noted, "is that less than 50 percent of the pesticides that were detected have established water-quality standards. Moreover, the effects of long-term exposure to pesticide mixtures are, as yet, unknown."
Pesticides were detected in surface water, ground water, bed sediment, and fish-tissue samples collected as part of the South Platte NAWQA study. Not surprisingly, the most commonly used pesticides were those most commonly detected.
The effects of human activity on water quality go beyond the concerns of drinking water--the aquatic ecosystem of the basin also has been affected.
"Surface water from agricultural and urban areas is not used for drinking water, but fish and invertebrate communities that live in these waters are affected by degraded stream-water-quality," Dennehy said.
"Although variability in the type and number of fish can be due to natural factors, including stream size, habitat characteristics, and hydrologic conditions, some variability can be attributed to human influence. For example, suckers, which are tolerant of pollution, dominate fish communities at sites affected by mining and in urban environments." Straightening stream channels, reducing bank vegation, and increasing bank erosion are some of the human activities that affect stream ecosystems.
Contaminants in all components of the environment --water, bed sediment, and fish -- are of concern. Although contaminants such as organochlorine pesticides and PCBs found in bed sediment and fish tissue have been banned from use since the 1970's, they have persisted in the environment for decades, which is important when considering that fish are a part of the natural food chain. The highest number and the highest concentrations of compounds were detected in the urban and mixed (urban/agriculture) areas. On a positive note, concentrations of these compounds in whole fish did not exceed US Food and Drug Administration standards for human consumption of fish fillets.
The South Platte River Basin covers parts of three states: 79 percent of the basin is in Colorado, 15 percent is in Nebraska, and 6 percent is in Wyoming. Land use in the basin is predominately rangeland (41 percent), but agriculture (37 percent) and urban or built-up (3 percent) areas have the largest effect on water quality. The population of the basin was about 2.7 million in 1995. About 90 percent of this population is clustered in the Front Range urban corridor (10 percent of the basin), which is located where the mountains meet the plains and is oriented in a north-south direction from Denver to Fort Collins, Colorado.
Copies of the 38-page, color report, "Water Quality in the South Platte River Basin, Colorado, Nebraska, and Wyoming, 1992-95," by Kevin F. Dennehy, David W. Litke, Cathy M. Tate, Sharon L. Qi, Peter B. McMahon, Breton W. Bruce, Robert A. Kimbrough, and Janet S. Heiny, published as USGS Circular 1167 are available free of charge from the USGS Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, (303) 202-4700 (fax request to (303) 202-4693). The Circular may be viewed on the World Wide Web at: http://water.usgs.gov/lookup/get?circ1167 click here for link
As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial, scientific information to resource managers, planners, and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, contribute to the sound conservation, economic and physical development of the nation's natural resources, and enhance the quality of life by monitoring water, biological, energy, and mineral resources.
For additional information contact:
Kevin Dennehy, Project Manager
South Platte River Basin NAWQA
(303) 236-4882 X312
kdennehy@usgs.gov
Peter McMahon, Water Quality Specialist
South Platte River Basin NAWQA
(303) 236-4882 X286
pmcmahon@usgs.gov
Additional information about the South Platte Basin NAWQA is also available at:
http://webserver.cr.usgs.gov/nawqa/splt/splt_home.html or click here for link
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The results of two U.S. Geological Survey water-quality studies in the Lower Susquehanna and Potomac River Basins provide a message that hits close to home for rural residents that drink water from private wells: Owners of rural wells in these two basins, part of the Chesapeake Bay watershed, need to ensure their water supplies are safe to drink.
The USGS studies found high levels of nitrate and high counts of bacteria in ground water from wells used for household supply in several rural areas. The study results underscore the need for awareness that untreated ground water may not always be safe to drink.
There was good news, however, about these same rural wells.
Concentrations of pesticides and other organic contaminants in the water from the wells did not exceed levels established by Federal and State agencies as drinking-water standards.
Of the well-water samples in which a pesticide was present, nearly 70 percent contained more than one detectable pesticide.
This is a significant new finding from the USGS studies.
"Human activities on the land surface, such as application of fertilizers and manure on croplands, have a significant effect on the concentration of nitrogen that ends up in the ground water or streams," said Scott Ator, USGS Hydrologist and principal author of the Potomac River Basin report. Ator's colleague, Bruce Lindsey, USGS Hydrologist and principal author of the Lower Susquehanna report, added, "Animal manure, used as an agricultural fertilizer, and commercial fertilizers are major sources of nitrogen and phosphorus in the Chesapeake Bay watershed. We now have good baseline data to measure changes as the new Pennsylvania law for nutrient management goes into affect this year."
"The old adage `Too much of a good thing' applies in certain areas," Lindsey said. Nitrogen in manure and fertilizers added to agricultural land is essential for plant growth; however, a concentrated animal operation can produce more manure than the crops grown on that farm can use. The numbers of concentrated animal operations are increasing in the basins.
Moving from the home front to the river front, the studies also provide an extensive baseline of information against which planners and water managers can measure the success of strategies for reduction of nutrients and toxics in tributaries to Chesapeake Bay.
Fish, streambed-sediment, and water samples were used to assess the occurrence of contaminants.
Contaminants in streambed sediment at some sites were detected at levels potentially harmful to aquatic life. Trace metals and long-banned organic contaminants are present in streambed sediment in the Lower Susquehanna and Potomac Rivers and their tributaries and have been incorporated into the food chain. These metals and contaminants were detected in clam and fish tissues. The use of PCBs, DDT, and chlordane has been banned or restricted for nearly 20 years, but these contaminants are still being detected in rivers and streams. The USGS cautioned that the fish were collected and analyzed to determine if contaminants were present, not to determine if the fish were safe to eat.
Being more specific, Ator said, "Mercury contamination from an industrial source near Waynesboro, Va., has led to measurable concentrations of mercury in sediment as far as 170 miles downstream on the Shenandoah River near Harpers Ferry, W. Va., even though the use of mercury at the Waynesboro site ended in 1950."
The studies of the Lower Susquehanna and Potomac River Basins, two of the largest watersheds that drain into Chesapeake Bay, were conducted by the USGS National Water-Quality Assessment (NAWQA) Program. The full-color reports summarize USGS studies that began in 1992 and are written to convey the technical findings to a wide audience including water managers, policy makers, other scientists, and the public. Details on the results of the studies and information on how to obtain copies of the reports are provided in the attached background statement.
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The full-color reports summarize USGS studies that began in 1992 in the Lower Susquehanna and Potomac Basins. Single copies of the reports, Water Quality in the Lower Susquehanna River Basin, USGS Circular 1168, and Water Quality in the Potomac River Basin, USGS Circular 1166, can be ordered free of charge from:
A limited supply is available at the USGS office in the Harrisburg area at 840 Market Street, Lemoyne, Pennsylvania 17043; telephone (717) 730-6900 and the USGS office in Baltimore at 8987 Yellow Brick Road, Baltimore, Maryland 21237; telephone (410) 238-4200.
For additional information about USGS programs and activities in Pennsylvania, Maryland, and other states in the Chesapeake Bay watershed, please visit our web site at: http://chesapeake.usgs.gov/chesbay/
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Forty percent (48 of 119) of water samples from wells in agricultural areas underlain by limestone contained nitrate concentrations that exceeded the U.S. Environmental Protection Agency's Maximum Contaminant Level for drinking water of 10 milligrams per liter. The limestone bedrock has features such as large fractures, caverns, and sinkholes that allow nitrate to move rapidly from the land surface to the ground water.
In limestone areas, ground water from springs made up a large part of the water in streams. Thus, high nitrate concentrations were found in spring-fed streams.
The amount of nutrients delivered to Chesapeake Bay is dependant upon the amount of rainfall. For example, 1996 was an exceptionally wet year and flood waters from these two rivers in 1996 carried large amounts of nutrients and suspended sediment to Chesapeake Bay.
Therefore, the reported trends were adjusted for these types of variations in streamflow. Despite an estimated 44-percent increase in population in the Potomac River Basin from 1970 to 1990, total-phosphorus concentrations in the Potomac River at Washington, D.C., have decreased since 1979 and nitrogen concentrations have apparently stabilized. There are downward trends in both total-phosphorus and total-nitrogen concentrations for the Susquehanna River at Conowingo, Md. Different forms of nitrogen, however, show differing patterns in long-term trends in both rivers.
Nitrate shows no change or upward trends for the Susquehanna and Potomac, respectively.
Nevertheless, the levels for total chlordane, total DDT, or total PCBs that must be exceeded in the edible portion before consumption advisories are issued were not exceeded in the whole-body tissues at any of the sampling locations.
A reconnaissance study of bacteria in well water was completed for the Lower Susquehanna Basin study. Total coliform bacteria were detected in water from nearly 70 percent of the household wells sampled, indicating that the water should not be used for drinking without treatment. Fecal coliforms and Escherichia coli, bacteria that indicate contamination by human or animal feces, were found in water from 25 and 30 percent, respectively, of the wells tested.
Few household wells from which water was sampled were grouted, and few had sealed, sanitary caps at the top of the casing.
Lack of these protective features can enable the entry of bacteria into well water. With annual testing recommended by county extension agents, owners of rural wells should keep an eye on the bacterial quality of their well water. Follow-up to this reconnaissance is needed; it is uncertain whether bacteriological contamination of well water is caused by inadequate protection of wells from surface runoff, septic-system failure, application of animal manure to fields, or a combination of these and other causes.
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