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Managing Wastewater in Coastal Urban Areas
Of 3,942 major POTWs4 operating in the United States, 3,116 are now operating in compliance with the Clean Water Act, and an additional 427 have plans to come into compliance over the next five years (EPA 1992a).
There have been notable improvements in the water quality problems targeted by these policies. Where they were once elevated, concentrations of lead, DDT, and PCBs in coastal fish, shellfish, and sediments are decreasing (NOAA 1990b). In Puget Sound, the once toxic and hypoxic waterways of Everett, Seattle, and Tacoma have recovered. Levels of DDT in fish of the Southern California Bight are 1 percent of what they were 20 years ago. The next section describes improvements in New York Harbor and the Delaware River Estuary. Improved treatment processes and phosphate detergent bans have resulted in notably fewer eutrophication problems in inland waters. All of these improvements have taken place in the face of large growth rates in coastal areas. National coastal monitoring programs confirm that, along much of the nonurban coastal zone of the United States, inputs and environmental concentrations of many waste materials and contaminants that were once in excess are now decreasing, or at least have stopped increasing (NOAA 1990b).
With some notable exceptions, many urbanized bays and estuaries are experiencing no such benefits. Blooms of noxious algae periodically plague portions of Long Island Sound, the New York Bight, Puget Sound and some southeastern estuaries. In most urban estuaries, shellfish beds are closed to commercial harvesting due to unacceptable concentrations of bacteria. In many urbanized bays and estuaries, warnings are posted to inhibit public consumption of chemically contaminated fish and shellfish and to deter public bathing at beaches where waters are contaminated.
Eutrophication, shellfish bed closures, and beach closures continue to affect many urban coastal areas. In a 1990 EPA report to Congress, all coastal states except Hawaii reported at least some impairment of designated uses of estuaries (EPA 1992b). Approximately 37 percent of estuarine waters classified for commercial shellfish harvest are closed or under harvest restrictions; sewage treatment plants, septic systems, and urban runoff are the three most frequently cited reasons for shellfish bed closures (NOAA 1991). Improvements in some areas have revealed new problems. For example, the upgrading of New York City's treatment plants has improved water quality in New York Harbor; however, it is now hypothesized that dissolved nitrogen in the cleaner effluent is entering Long Island Sound where it causes eutrophication problems, particularly during the summer (Parker and O'Reilly 1991, Swanson et al. 1991). Off the coast of Los Angeles County, the upgrade to chemically-enhanced primary treatment and
A major publicly owned treatment work is defined as one discharging more than 1 million gallons per day.