Abstract
Surface-water supplies are important sources of drinking water for residents in the Triangle area of North Carolina, which is located within the upper Cape Fear and Neuse River Basins. Since 1988, the U.S. Geological Survey and a consortium of governments have tracked water-quality conditions and trends in several of the area’s water-supply lakes and streams. This report summarizes data collected through this cooperative effort, known as the Triangle Area Water Supply Monitoring Project, during October 2008 through September 2009. Major findings for this period include:
- Annual precipitation was approximately 20 percent below the long-term mean (average) annual precipitation.
- Streamflow was below the long-term mean at the 10 project streamgages during most of the year.
- More than 7,000 individual measurements of water quality were made at a total of 26 sites—15 in the Neuse River Basin and 11 in the Cape Fear River Basin. Forty-seven water-quality properties and constituents were measured.
- All observations met North Carolina water-quality standards for water temperature, pH, hardness, chloride, fluoride, sulfate, nitrate, arsenic, cadmium, chromium, lead, nickel, and selenium.
- North Carolina water-quality standards were exceeded one or more times for dissolved oxygen, dissolved oxygen percent saturation, chlorophyll a, mercury, copper, iron, manganese, silver, and zinc. Exceedances occurred at 23 sites—13 in the Neuse River Basin and 10 in the Cape Fear River Basin.
- Stream samples collected during storm events contained elevated concentrations of 18 water-quality constituents compared to samples collected during non-storm events.
- Concentrations of nitrogen and phosphorus were within ranges observed during previous years.
- Five reservoirs had chlorophyll a concentrations in excess of 40 micrograms per liter at least once during 2009: Little River Reservoir, Falls Lake, Cane Creek Reservoir, University Lake, and Jordan Lake.
|
|
First posted October 2, 2014
- Table 1 and 2 XLSX (105 KB)
Table 1. Water-quality and streamflow monitoring sites for the Triangle Area Water Supply Monitoring Project, October 2008 through September 2009 (22.4 KB)
Table 2. Summary of water-quality results for sampling sites in the Triangle Area Water Supply Monitoring Project, October 2008 through September 2009
(82.5 KB).
Part or all of this report is presented in Portable Document Format (PDF). For best results viewing and printing PDF documents, it is recommended that you download the documents to your computer and open them with Adobe Reader. PDF documents opened from your browser may not display or print as intended. Download the latest version of Adobe Reader, free of charge. More information about viewing, downloading, and printing report files can be found here.
|