Primary Sources of Pollution

The majority of beach closings in the United States result from testing that indicates high levels of harmful bacteria, viruses, and other pathogens are present in beach water. High levels of these pathogens through ingestion, body contact and inhalation increases the public's risk of illness.

Before the passage of the Clean Water Act of 1972, water pollution from untreated sewage was common and widespread. This landmark legislation has dramatically reduced the amount of harmful pollutants entering U.S. waters, but the volume of wastewater continues to increase as our population grows. Recently collected beach water quality information shows the major sources of pathogens in beach water are untreated or partially treated sewage and storm water runoff spilling onto the beaches and from overflowing sewage collection and treatment facilities.

Sewer Overflows

EPA and state environmental protection agencies work with local communities to ensure that sewage collection and treatment systems are properly installed, operated, and remain functional. Under normal operating conditions, sewage from homes and businesses is carried to wastewater treatment facilities where it is properly treated and tested before it is discharged.

Older or malfunctioning sewer systems may have leaking or damaged pipes and connections. Some systems may be simply overloaded because they are serving communities larger than those for which they were designed. During storms or even under dry conditions these systems can spill or leak raw sewage into our waters.

About 900 cities in the United States have combined sewer systems. These systems were designed years ago to carry both raw sewage and storm water runoff (rain and snow melt) to a treatment plant. They were also designed to discharge excess wastewater into local waterways when the system became overloaded. During heavy rainstorms, for example, overloaded combined sewer systems may discharge a mixture of raw sewage, polluted runoff and litter from streets and, in some cases, industrial waste waters, into local waterways where it can contaminate downstream beaches and other areas. In 1994, EPA established a national strategy to greatly reduce the number of combined sewer overflows causing human health and environmental problems.

San Francisco: Controlling Sewer Overflows

The City of San Francisco spent $1.45 billion and twenty years building a system to control combined sewer overflows. As part of the project, the city built large underground structures that act like a moat surrounding the city's shoreline, intercepting sewage and urban runoff that otherwise would have been discharged into local water bodies. The structures trap, temporarily store, then transport the mixture of storm water and sanitary sewage to upgraded treatment facilities. Eighty-five percent of the sewage and storm water that would otherwise be discharged on the beaches is captured and treated at wastewater treatment plants. The remaining 15 percent gets flow-through treatment in the storage/transport system before it is discharged.

Before the control structures were built, the city had between 50 and 80 untreated overflows on to its shorelines each year. Now that the new system is in place, overflows range between 1 and 10 per year.

Polluted Storm Water Runoff

In some cities in the United States, separate storm sewer systems collect and transport rainwater and snowmelt to treatment facilities before releasing it into a river, stream, or bay. When storm water sewers are over-loaded they discharge directly into these waters. Rainwater also flows to our beaches after running off lawns, farms, streets, construction sites, and other urban areas picking up animal waste, fertilizer, pesticides, trash, gasoline, oil, and many other pollutants.

In an effort to reduce health risks associated with the discharge of untreated storm water into local waterways, EPA and representatives from State and municipal government health and environmental protection agencies have been working collectively to increase the capacity of storm water collection systems and reduce discharges of untreated storm water into surface waters.

Santa Monica Finds Health Risk Directly Related to Storm Drains

Storm drain outlets pollute more than two miles of Santa Monica's beaches. In the summer of 1995, more than 15,000 people were interviewed immediately after swimming near storm drains and again 9 to 14 days later. In the second interview, swimmers were asked whether they had any symptoms of illness such as fever, chills, eye discharge, earache, skin rash, vomiting, diarrhea, or sore throat.

During the study, researchers collected daily water samples at various distances from the drain outlets and analyzed the water for the presence of indicators of disease-causing pathogens. They found that people who swam directly in front of storm drain outlets had a higher incidence of symptoms than people who had been swimming 400 yards away.

Santa Monica is working to reduce the risk from its storm drains with street sweeping, catch basin cleaning, and other measures. The city has also established an outreach program to alert the public to the hazards of swimming near storm drain outlets.

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