Non-point Source Pollution: Reducing Its Impact on Coastal Environmental Quality Dan Walker, Ph.D.

Thank you Admiral Watkins and commission members for allowing me this opportunity to draw your attention to two recent reports of the National Academies that address what are arguably two of the most significant challenges to coastal and marine environmental quality: oil pollution and nutrient pollution. A decade ago public concerns about marine pollution were driven by the dramatic footage from Prince William Sound taken in the days and weeks following the Exxon Valdez oil spill. In more recent years many coastal residents have come to recognize a new but equally damaging problem: surface runoff. Last year saw a record number of beach closings, and 2002 seems to be keeping pace. Beach closings, harmful algal blooms, and hypoxia events such as the well-documented “dead zone” in the Gulf of Mexico, have pushed non-point source pollution to the top of most lists as the major threat to coastal environmental quality. In 1998, at the request of NOAA, EPA, the USGS, and the Electric Power Research Institute, the National Academies undertook a two-year effort to provide advice on one of the most prominent non-point source pollution threats: nutrient over-enrichment. The final report, entitled Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution, provided a detailed analysis of the scientific and management issues posed by nutrient pollution and outlined the key elements of a nationwide strategy to address the problem. Now a recently released National Academies report Oil in the Sea III: Inputs, Fates, and Effects suggests that oil may need to join nutrients, pesticides, and mercury on the list of non-point source pollution threats to the coastal environment. New estimates reported in Oil in the Sea III indicate that spillage from vessels in North American waters from 1990 to 1999 was down by nearly two-thirds compared to the prior decade, and reductions in releases during oil and gas exploration and production have been dramatic as well. These releases, however, represent only about 30 percent of the worldwide petroleum inputs to the sea from human activity. Chronic low-level releases associated with the consumption of petroleum account for the other 70 percent and may pose significant risks to the sensitive estuarine environments where these inputs most often enter the marine environment. Volumetrically the most significant anthropogenic source of petroleum entering the marine environment is land-based, nonpoint source pollution, which delivers roughly 16 million gallons of petroleum to North American coastal waters each year, over half of the total anthropogenic load. The effects of a petroleum release are a complex function of the rate of release, the nature of the petroleum, and the local physical and biological characteristics of the exposed ecosystem. Some hydrocarbon components are more toxic than others. Growing evidence suggests that toxic compounds, such as polycyclic aromatic hydrocarbons (PAH) in crude oil, refined products, or rivers or wastewater streams polluted with petroleum, can have adverse effects on biota at very low concentrations. This suggests that PAH released from chronic sources may be of greater concern than was recognized 10 to 15 years ago, and that in some instances effects of petroleum spills may last longer