WASHINGTON (AP) — A new report by the Environmental Integrity Project is calling for tougher state permitting and oversight to achieve Chesapeake Bay restoration goals.

The environmental group released the report on Thursday, saying impressive gains have been made in reducing nitrogen pollution in the bay. However, further reductions will require tougher permitting and oversight. The group found nitrogen discharges from industrial and municipal sewage treatment plants studied declined significantly in Maryland and Virginia in 2011. Pennsylvania increased 4 percent.

However, the report says 12 percent of the largest plants studied violated nitrogen permit limits for at least a quarter in 2011.

Nitrogen is a key bay pollutant. Sources include sewage, fertilizer and automobile and power plant emissions. In the bay, it can spur oxygen-robbing algae blooms.

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