While many don’t give it a second thought, others wonder about the cleanliness of the water, and if what they are doing is safe. During the summer, ICPRB staff sometimes field several calls a week from people wanting to know if a favorite spot on their local river or stream is “safe.” With few exceptions, we are unable to provide a definitive answer.

Can I Swim?
The main concern for water contact recreation (swimming, wading, water skiing) generally is bacterial levels. While bacteria are integral parts of any natural system, some kinds, in sufficient numbers, can cause gastrointestinal illness, skin and ear infections, respiratory illness, and sometimes worse problems. At many areas designated as bathing beaches, or at parks where wading or swimming is officially allowed, water testing is conducted weekly for bacterial contamination. Tests involve examining a water sample for indicator bacteria that signal conditions conducive to the growth of the several types of bacteria that can cause gastrointestinal illness or other infections in people.

Particular areas in which people swim from an uncontrolled beach or from a boat may or may not have a water quality monitoring station in the general area. Many stations are monitored only monthly, and many of those don’t test for bacteria. A typical call could be “I like to water ski with my family downstream of Alexandria, Va. Will we get sick?” Although helpful data is not available,  we do provide some general guidance, listed below.

Where does the Contamination Come From?
In past decades, sewage treatment plants were a major cause of bacterial loads in the river. That isn’t so true any more. Most sewage plants in the region treat to a high degree, and disinfect the water before it is discharged. However, broken sewer pipes that collect waste for transfer to the plant can leak raw sewage into waterways. Heavy rains can cause flows that overwhelm treatment plants. Like any other mechanical device, treatment plants sometimes malfunction and sewage overflows to the river. Septic systems in rural areas also can fail, or be overloaded by rains.

Other major contaminant sources are mostly related to storm water runoff. Storm water from streets and rooftops of urban and suburban areas carries bacteria-laden trash, pet waste, and other pollutants. In rural areas, agricultural operations can contribute animal manure and processing by-products, sediment, and fertilizer. Beach areas with populations of geese and ducks can show elevated bacteria levels. The pace and methods in which land is developed and used can cause bacteria problems in local waterways. Additionally, older urban areas, including a large portion of Washington, are served by old, combined sewer systems that route sewage and stormwater through the same pipes. Significant rains cause the pipes to back up, and a mixture of sewage and storm water that normally goes to a treatment plant  backs up and discharges directly to a waterway or river. This kind of pollution frequently affects the Anacostia River and Rock Creek, and can affect the adjacent segment of the Potomac.

So what can you tell us about the safety of my local stream or river?
Bacteria levels can change rapidly with rain events. Except for parks and other facilities where swimming and wading is a sanctioned activity, water monitoring is done at often far-spread stations, usually monthly. Many of these areas are heavily used, without reports of outbreaks of gastrointestinal illness. Without good data, people must decide based on their attitude toward risk and their personal level of health. The odds of a person getting sick increase with the amount of bacteria that enter the body. A small amount is unlikely to affect most people. For that reason, boating, where people may just get splashed occasionally, is much less risky than swimming.

When people do choose to swim in the Potomac, there are a number of things they can do to limit any risk.
*Don’t enter the water for several days after a significant rainstorm. Storm flows spike bacteria levels, which decrease after several days.
*Don’t swallow water.
*Don’t enter the water if you have cuts or open sores. These are pathways for bacteria to enter your body.
*Wash after swimming.        
*People with immuno-suppressive diseases, or generally poor health should avoid contact with the river.

If the residents of the basin want a swimmable Potomac–and its tributaries that make up our local streams–both governments and the citizens of the basin will need to make strong commitments to improve water quality. Government agencies tasked with the work will require strong public and monetary support. State and local agencies face competing budget priorities at the same time that land is being developed at a rapid pace. Citizens need to voice their demands for a cleaner environment while becoming stewards of their local waterways. The ICPRB promotes stewardship through a variety of outreach and education projects.

People who want to know about bacterial levels in their local waterway should start with their county health department, but the information needed may not exist. Maryland and Virginia host websites that list stations tested for bacteria and their current status, with contacts for some county health departments. For more information, visit or call:

• Maryland: http://mddnr.chesapeakebay.net/eyesonthebay/swim_beach_info.htm

• Virginia: http://www.vdh.virginia.gov/epidemiology/DEE/BeachMonitoring/

• Pennsylvania: call 1-877-PA-HEALTH

• West Virginia: Office of Environmental Health Services, Dept. of Health and Human Resources, (304) 558-2981, or county health departments.

• Washington, D.C.: Swimming is not an approved activity in the waters of the District of Columbia.