You see references to recreational water quality standards all over Swim Guide. It is a technical term used by governments and scientists, but you probably don’t use the phrase in day-to-day life. What does it mean?
“Standards” are limits set by official agencies – usually governments – based on the advice of scientists. Standards say what the maximum concentration of a contaminant in air or water can be before there is unacceptable risk to people or the environment. For example, the maximum concentration of E. coli in water may be 100 units of E. coli for every 100 millilitres of water.
Standards sometimes also set the maximum amount of a contaminant that can be put into air or water. For example, the maximum amount of mercury that can be released into waters in part of Minnesota is 26 kilograms per year.
Standards may be legally binding, meaning that anyone who puts contaminants into the water that doesn’t meet the standards could be charged or fined. Standards may also be voluntary, meaning that there is no penalty for failing to meet them. Voluntary standards are often called “guidelines”. Usually, guidelines are incorporated into conditions in a legal document like a permit or a grant to make them enforceable.
These are parts of natural waterbodies where you engage in recreational activities, like swimming or boating.
Water quality standards are the rules and guidelines that specifically deal with what you can put into the water. They are different from air quality standards or soil standards.
Some water quality standards refer to the natural environment – what is in your lake, river, or ocean. Some water quality standards refer only to drinking water – what is in your tap water.
Recreational standards specifically focus on water quality in the places where people are most likely to be swimming or boating. “Primary” contact means you are putting your whole head under water, like when you swim, dive, or surf. “Secondary” contact means that you are near the water, like when you paddle, sail, or fish. Standards for primary contact are more strict, because there is a good chance that you’ll be swallowing some of the lake.
Recreational standards usually focus on indicator bacteria, which are used to detect the level of fecal contamination in the water. They are considered a better indicator of human sewage than other types of bacteria because they are found in intestines of warm blooded animals.
E. coli is the type of bacteria that local health authorities look for in freshwater. Enterococci is the indicator bacteria for marine and brackish waters.
The standards for recreational water quality differ greatly from place to place. Below is a summary of the primary contact recreational water quality standards Swim Guide uses for Canada, the US Environmental Protection Agency (EPA), New Zealand and Mexico.
Primary contact with water containing high levels of faecal bacteria and other pollutants can lead to disease, infection, and rashes. Swallowing contaminated water can lead to gastrointestinal infection such as nausea, diarrhoea and vomiting. More serious diseases and illnesses may also be contracted in heavily polluted waters including typhoid fever, hepatitis, gastroenteritis, and dysentery.
Even when you are on or near but not “under” the water, there is still a risk to your health from touching and inhaling water contaminated with bacteria and other pollutants. Skin contact with contaminated water can cause rashes and other skin problems. Bacteria can enter the body through openings, such as ears, nose, eyes, and through cuts and scrapes in the skin. Furthermore, inhaling contaminated water can lead to respiratory illnesses, and infections in the eyes, ears, and nose.
Anyone can be affected from exposure to contaminated water, but small children, the elderly, and people with compromised immune systems are the most vulnerable.
Not necessarily. Because recreational standards are specifically looking for sewage pollution, they don’t look for industrial pollution. Water may have metal or oil pollution but no E. coli. Water can be bacteria-free, but still dirty.
Similarly, bacteria in the water is not the only hazard at the beach. Tides and currents, drop offs, and sharp objects also pose a threat. Just because water is “clean”, it doesn’t mean it is also “safe”.
|Geometric Mean (GM) per 100 ml||Magnitude: Geometric Mean (GM) per 100ml||Combination of qualitative risk grading and direct measurement of faecal indicators||Geometric Mean (GM) of Most Probable Number (MPN) of enterococci per 100ml|
|The waterbody GM should not be greater than the selected GM|
magnitude in any 30-day interval
|The waterbody GM should not be greater than the selected GM magnitude in any 30-day interval||N/A||The waterbody GM should not be greater than the selected GM magnitude in any 30-day interval|
Freshwater Quality Standards (E.Coli)
|A max GM (min five samples) of 200 e.coli/100ml|
Single-sample max concentration of 400 e.coli/100ml
Ontario’s Ministry of the Environment set the standard at 100 e.coli/100ml for the GM of five samples
A max GM of 126 e.coli/100ml
|Single sample max concentration of 235 e.coli/100ml||Alert/Amber Mode: single sample greater than 260 e.coli/100ml|
Action/Red Mode: single sample greater than 550 e.coli/100ml
Marine (salt) Water Quality Standards (Enterococci)
|A max GM of 35 enterococci/100ml and a single sample max of 70/100ml||A max GM of 33 enterococci/100ml and a single sample max of 62/100ml||Alert/Amber Mode: single sample max of 140 enterococci/100ml|
Action/Red Mode: single sample max of 280/100ml
|A max GM of 200 MPN of enterococci/100ml|
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