Urban Runoff Top Cause of North Carolina Impaired Waters

RALEIGH, North Carolina, May 7, 2004 (ENS) - The number one rated source of impairment of North Carolina's bodies of water is urban runoff and storm sewers, according to a new biennial state assessment. Stormwater runoff carries natural and human pollutants into waterbodies that may include sediment, nutrients, bacteria, oil and grease, trace metals, toxic and synthetic chemicals.

The North Carolina Division of Water Quality is seeking comment on its draft updated assessment of waterbodies in the state, including a list of impaired waters and strategies for water quality improvement.

Updated every two years, the assessment is a comprehensive accounting of how well surface waters, groundwaters, and wetlands support their designated uses, such as swimming, aquatic life support and water supply.

The report lists which waters do not support their designated uses and the likely causes of impairment.

The most common sign of impairment is poor biological integrity - more than 1,600 miles of streams are impaired by this standard. Poor biological integrity means that the stream does not have an appropriate number or variety of aquatic bugs that are large enough to be seen with the naked eye.

These animals, mainly aquatic insect larvae, are sensitive to subtle changes in water quality and can be indicators of a wide range of environmental stresses.

They are stressed by exposure to chemical or physical pollutants, such as toxic chemicals or oxygen consuming wastes. More stress arises from habitat degradation such as loss of riffles and pools due to sedimentation or scouring due to increased force of waters from storms or wetlands loss.

“We have enhanced our ability to identify the sources and relative effects of such stresses and completed more than 20 studies of specific streams over the last two years,” said Michelle Woolfolk, environmental supervisor in the Division of Water Quality’s planning branch and one of the authors of the report.

Use support ratings for each of the state’s 17 river basins are evaluated every five years on a rotating basis as the basinwide management plans are revised. This year, use support ratings for the Broad, Neuse, and Yadkin-Pee Dee river basins have been updated since the 2002 report.

Work has begun on a program to define and characterize Piedmont and Mountain area groundwater hydrology in cooperation with the U.S. Geological Survey.

Knowledge of the quality and availability of the shallow aquifer system, its vulnerability to contamination, and its relationship to the recharge of surface water resources is necessary in order to provide appropriate levels of protection for present and future use. Four research stations were completed in 2003 and reports from these sites will be available this year.

Comments on the draft report and impaired waters list are welcome through May 31 to Robin Markham at: robin.markham@ncmail.net

The 2004 Water Quality Assessment and Impaired Waters List is available on the DWQ’s Web site at: http://h2o.enr.state.nc.us/tmdl

The Division of Water Quality will submit the final list to the U.S. Environmental Protection Agency by June 30.