Every year, thousands of people become ill from visiting the beach or a lake or even from taking a peaceful float down a river. Why?
Runoff from urban areas or agricultural regions can carry sewage or animal waste into streams and rivers, which flow into local lakes (and drinking water reservoirs) or to the ocean. The risk of this happening is higher after rainfall events because rain flows over the land and into our waterways, filling up creeks and streams. In many urban areas, sewage treatment plants cannot handle the inflow of water that comes from a heavy rain event. When this happens, the treatment plant discharges excess waste into surface waters so the sanitation system does not shut down.
Yes, you read that right – raw sewage gets released into our rivers and lakes, on purpose, by the people responsible for keeping our water clean. That waste can carry pathogens that can make us sick. This is of particular concern for people with weakened immune systems, such as the elderly or the very young, who are more susceptible to illnesses.
Another concern is blue-green algae, also known as cyanobacteria. Excess fertilizer and other nutrients that run off yards and farm fields lake can cause the growth of blue-green algae, which can turn toxic in the water. Swallowing water that contains cyanotoxins can cause health problems ranging from allergic reactions to liver and kidney failure, especially for people with compromised immune systems and children under age 6. (Even pets are at risk! )
To avoid getting sick, there are a few precautions you can take. First, take notice of warnings from the health department or posted signs at your favorite swimming hole. If they say it is unsafe to swim, DO YOURSELF A FAVOR AND DO NOT SWIM. Avoid swallowing water while swimming no matter where you are, and swim in areas with lots of water circulation, since pathogens and cyanobacteria are less likely to accumulate there.
There is another lesson here: what we do on the land affects our ability to enjoy the outdoor recreation we love. By applying fertilizer mindfully to our yards (test your soil first to see if it really needs the nutrients) and controlling runoff that leaves farm fields and urban areas, we can decrease the likelihood that algae and pathogens will multiply in our swimming spots. Planting trees, building infrastructure that reduces runoff, and using water wisely in our homes are all ways to help this effort. Preventing runoff may help you avoid a summertime illness.
And don’t forget your sunscreen!