- How serious and extensive is beach pollution in the United States?
- What are the primary causes and sources of water pollution at beaches?
- What harmful microorganisms can be found in polluted water and what illnesses do they cause?
Past monitoring studies have shown that beach pollution is usually infrequent or confined to local areas. Problems can develop in areas near pollution sources after a heavy rainfall or when a sewage treatment plant malfunctions. Pollution can also occur from disruption or damage to wastewater collection and treatment infrastructure due to severe natural events like hurricanes or flooding.
There is not enough information available now to define the extent of beach pollution throughout the country. A few states have comprehensive beach monitoring programs to test the safety of water for swimming. Many other states have only limited beach monitoring programs, and some states have no monitoring programs linked directly to water safety at swimming beaches.
What we do know is that beach pollution is a persistent problem, based on the number of beach closings and swimming advisories that continue to be issued annually. Nearly 4000 beach closings and swimming advisories were issued by state and local governments in 1995. Most problems with beach pollution have been reported for ocean, bay, and Great Lakes beaches, but these problems are not limited to coastal areas. However, we currently do not have access to information about the safety of swimming beaches at rivers and other lakes across the country.
A primary goal of the Beaches Environmental Assessment, Closure, and Health (BEACH) Program is to work with state, tribal, and local governments to compile information on beach pollution to define the national extent of the problem.
The majority of beach closings in the United States are due to indications of the presence of high levels of harmful microorganisms found in untreated or partially treated sewage. Most of this sewage enters the water from combined sewer overflows, sanitary sewer overflows, and malfunctioning sewage treatment plants. Untreated storm water runoff from cities and rural areas can be another significant source of beach water pollution. In some areas, boating wastes and malfunctioning septic systems can also be important local sources of beach water pollution.
Combined sewer systems are designed to carry both raw sewage and storm water runoff to sewage treatment plants. During heavy rainstorms, these systems can become hydraulically overloaded and discharge a mixture of raw sewage and polluted runoff from streets into local waterways. The discharges pollute water around the outfalls and at downstream beaches.
Heavy rainfall can also hydraulically overload separate sanitary sewer systems which carry raw sewage to sewage treatment plants. This is especially a problem for systems with excess infiltration of rainfall through the ground into leaky sanitary sewers and with large inflows from sources such as roof drains connected directly to sewers. When flows exceed the capacity of the system, sewers can overflow and discharge untreated sewage from manholes and bypasses at pump stations and sewage treatment plants. The discharges flow into local waterways and pollute the water.
People who swim in water near storm drains can become ill. A recent Southern California epidemiological study, for example, revealed that individuals who swim in areas adjacent to flowing storm drains were 50 percent more likely to develop a variety of symptoms than those who swim further away from the same drain. Swimmers who did not avoid the drains experienced an increased risk for a broad range of adverse health effects. These include fever, nausea, and gastroenteritis; flu-like symptoms -- such as nasal congestion, sore throat, fever, and/or coughing-- are also possible. Storm drains can even be a source of problems during drier weather because broken pipes or connections to sanitary disposal systems may contribute pathogens to the storm drains.
Polluted runoff and untreated sewage released into the water can expose swimmers to bacteria, viruses, and protozoans. These pathogens (disease-causing organisms) can be present at or near the site where polluted discharges enter the water. Children, the elderly, and people with weakened immune systems are most likely to develop illnesses or infections after swimming in polluted water.
Swimming-related illnesses are typically minor. This means that they require little or no treatment, respond readily to treatment, and have no long-term health effects. The most common illness associated with swimming in water polluted by sewage is gastroenteritis. It occurs in a variety of forms that can have one or more of the following symptoms: nausea, vomiting, stomachache, diarrhea, headache, and fever. Other minor illnesses associated with swimming include ear, eye, nose, and throat infections. In highly polluted water, swimmers may occasionally be exposed to more serious diseases like dysentery, hepatitis, cholera, and typhoid fever.
Agencies monitoring for beach water pollution usually analyze the water samples they collect for indicator species to assess the water for harmful levels of pathogens. Collecting and measuring the pathogens directly can be difficult and potentially hazardous. Good indicator species are microorganisms that are easy to collect and analyze for, safe to handle, representative of the pathogen of concern for characteristics like growth, and always present when pathogens are present or vice versa.