Our Great Lakes

Can We Swim at the Beach?

Every summer, the long, sandy beaches that ribbon Great Lakes shorelines draw millions of people seeking relief from the heat and a chance to be closer to nature. We want to be able to swim without worrying about getting sick from the water.

What is happening?

The water along most Great Lakes beaches is safe for swimming most of the time. But, at some times and places beach water is too contaminated for safe swimming. High bacteria levels in the water can give swimmers a number of illnesses, including skin rashes, intestinal upsets, and ear and eye infections. When bacteria levels rise beyond government standards, beaches are closed to swimming or warnings are posted.

The causes of bacterial problems on beaches are much the same as those in drinking water. Malfunctioning or overloaded sewage treatment plants, leaking septic tanks, and untreated discharges from boats all lead to human waste entering the environment. Runoff may become contaminated by pet droppings and droppings from geese and gulls in urban areas, and by animal waste from pastures and farms. In towns and cities, rainstorms can send too much water into sewage systems, particularly those that combine sanitary system and storm sewer pipes. The sanitary sewers take wastes away from our homes, while storm sewers carry rainwater and snowmelt from roofs, yards, parking lots, and streets.

When these systems are overloaded by stormwater, sewage treatment plants release untreated or partially treated wastes to avoid being flooded. This water is discharged into the Great Lakes and can pollute nearby beaches. Storm sewers that are separate from the sanitary system have traditionally discharged untreated water into lakes and rivers. In recent years, we have come to realize that this water carries contaminants from urban runoff. As a general rule, the farther a beach is from settled areas or from intensive livestock farming, the lower the risk of bacterial contamination on that beach.

What is being done?

Sewage treatment systems are being built or upgraded to capture and treat polluted water. The biggest challenge is to further reduce the amount of untreated stormwater that flows into the Great Lakes. A number of strategies to control this source of pollution have been developed. They include building holding ponds and underground storage tanks to keep polluted water from rushing into the lakes so that it can be processed at sewage treatment plants after the storm has passed. Wetlands are being reintroduced in some urban areas to filter pollutants out of the water naturally.

Individuals can play an important role in reducing stormwater. Homeowners are encouraged to disconnect downspouts from municipal sewer systems and let water from their roofs flow into rain barrels or directly onto lawns and gardens. Diverting water in this way takes pressure off sewer systems and reduces the risk of sewer water backing up into basements. People can use porous materials for walkways, driveways, and patios so that rain and snowmelt will seep into the ground rather than draining into the sewer systems. These measures also reduce the need for lawn watering.

To give swimmers better warnings of beach contamination, federal, state, provincial, municipal, and Tribal and First Nations governments have increased the number of tests of swimming water quality. Governments are using tougher standards for acceptable bacterial levels in water and are improving sampling and testing methods. As a result of more stringent tests, some beaches may appear to be more polluted than they were in the past, but they are simply better monitored. One of the problems facing public health officials is that it takes time to sample and analyze water, which means that a contaminated beach may remain open for a day or two while tests are being done. By the time the beach is posted as unsafe for swimming, the bacterial levels in the water may have dropped. Officials are testing rapid sampling technologies that will enable them to spot problems earlier. Since rainfall is closely linked to a rise in bacterial levels along many beaches, officials are trying to predict the need for beach closings on the basis of both the amount of rain that falls in a storm and mathematical models that predict the likelihood of unsafe coliform levels.

To further improve swimming conditions, the United States has set a goal that, by 2010, 90 percent of monitored high-priority beaches around the Great Lakes will meet standards for bacteria (E. coli and fecal coliform) for more than 95 percent of the swimming season. In Canada, the City of Toronto is adopting the Blue Flag approach to certifying beaches as safe. Other communities are expected to follow this example.

Figure 3: Percentage of the swimming season when monitored Great Lakes beaches were safe for swimming. While four years of data are presented, trends over time are difficult to accurately interpret because measurement techniques have changed, monitoring has increased, water quality standards have been made stricter, and pollution levels and annual rainfall, which affects pollution, vary. For a further listing of beach conditions around the Great Lakes, see the BeachCast website at http://www.great-lakes.net/beachcast.