Nutrient pollution is the largest problem facing the Inland Bays.
Point source pollution originates from a pipe, such as discharge from a wastewater treatment plant.
Nonpoint source pollution originates from diffuse sources and enters the Bays through groundwater and surface runoff. Sources include fertilizers, septic systems, land application of wastewater, and stormwater runoff.
Atmospheric sources originate from the emissions of power plants, automobiles, and agriculture that later deposit directly onto the surface of the Bays. The maximum amount of nutrient pollution that a water body can receive and still support healthy environmental conditions is called its Total Maximum Daily Load (TMDL). In 1998, state regulations established target loads for the Inland Bays. The regulations require elimination of all point sources, a 40 to 85% reduction of nonpoint source loads, and a 20% reduction of loads from atmospheric deposition. In 2008, the Delaware Department of Natural Resources and Environmental Control enacted a Pollution Control Strategy (PCS) that laid out a series of regulatory and voluntary actions needed to meet the TMDL.
After decreasing by over 80% since the 1990s, point source pollution decreased only slightly since the last report, and two point sources remain in the Bays.
Nonpoint source nitrogen loads remained far in excess of healthy limits in all bays, but loads to Little Assawoman Bay may now be decreasing. Phosphorus loads on average were within healthy limits for Rehoboth and Little Assawoman Bays, but continue to exceed healthy limits for Indian River Bay.
Atmospheric nitrogen loads are now within healthy limits.
Substantial progress was made on conversions of septic systems to central sewer, far surpassing the pollution reduction goal.
Voluntary agricultural and stormwater nutrient management practices yielded very little progress, highlighting the need for dedicated funding for these most important bay restoration actions.