Approximately 80 percent of Charlotte’s drinking water supply comes from Mountain Island Lake. Three municipal water systems have intakes on the lake: Charlotte-Mecklenburg, Gastonia and Mount Holly. Those systems also provide water to the communities of Stanley, Ranlo, McAdenville, Cramerton, Lowell and Clover, S.C. for a total of more than 750,000 people who get their drinking water from the lake.
The Marine Commission monitors reports from both government and non-profit organizations that test the water for biological and chemical contaminants. The water quality is generally excellent, with some elevated levels of e-coli reported after heavy rains. The out-flow from ash ponds at Duke Energy’s Riverbend Steam Station is also closely monitored.
Mecklenburg County’s Division of Storm Water Services’ water quality staff continually tests the water in Mountain Island Lake and the creeks that flow into it. They investigate pollution concerns, identify and eliminate pollution sources, and enforce state and local water quality regulations. The unit uses water quality data to identify pollution sources and track overall water quality trends. Representatives report their findings to the Marine Commission at its monthly meetings.
The N.C. Division of Public Health has issued a fish consumption advisory for channel catfish and largemouth bass in Mountain Island Lake. Elevated levels of PCBs were found in the channel catfish, and elevated levels of mercury have been found in largemouth bass in all of North Carolina’s waters. The state, in cooperation with the Mecklenburg County water quality staff has sampled additional species of fish and is expected to report in early 2012.
Another water quality concern is sedimentation caused by shoreline erosion as well as storm water runoff from construction sites in the watershed farther from the lake. The Marine Commission monitors development in the lake’s watershed to assure appropriate construction practices protect the water. The Catawba Riverkeepers organization checks the lake for sedimentation through its Muddy Water Watch. Trained volunteers use secchi dishes to test the clarity of the water. They report to the Marine Commission monthly on water quality and other environmental issues.