The U.S. Environmental Protection Agency is seeking comments on its proposed guidelines to control the discharge of pollutants from construction sites. The proposal would require all construction sites to implement erosion and sediment control best management practices to reduce pollutants in stormwater discharges.

Construction activities such as clearing, excavating and grading significantly disturb the land. The disturbed soil, if not managed properly, can easily be washed off the construction site during storms and enter streams, lakes and other waters. Stormwater discharges from construction activities can cause an array of physical, chemical and biological impacts.

Sediment is one of the leading causes of water quality impairment nationwide, including reducing water depth in small streams, lakes and reservoirs.

The proposal also notes that, for certain large sites located in areas of the country with high rainfall intensity and soils with a high clay content, stormwater discharges from the construction site would be required to meet a numeric limit on the allowable level of turbidity, which is a measure of sediment in the water. In order to meet the proposed numeric turbidity limit, many sites would need to treat and filter their stormwater discharges.

This proposed rule is projected to reduce the amount of sediment discharged from construction sites by up to 27 billion pounds each year, at an annual cost of $1.9 billion. The benefits from reducing discharges of sediments include better protection for drinking water supplies, improvements in aquatic environments (e.g., reduced streambed smothering), and less need for dredging of navigation channels and reservoirs.

To comment on this proposal, go to www.regulations.gov and search for document EPA-HQ-OW-2008-0465. Comments are due by the end of February 2009.