Water Quality 101
What is a watershed?
Simply put, a watershed is the area of land that drains to a particular waterbody. A watershed can vary in size depending on how you look at things. For example, in Central Minnesota our major watershed is the Mississippi River basin that drains to the Gulf of Mexico. But on a smaller scale, watersheds can be thought of as your neighborhood that drains to the backyard pond and ultimately to the Mississippi River.
For example, the Mississippi River–St. Cloud watershed covers 691,200 acres. So when it rains or when snow melts anywhere in the watershed, the water soaks into the ground, enters storm drains and pipe or runs over land until water ultimately reaches the Mississippi River.
Where is my watershed?
Find out about your major watershed.
To learn where your stormwater goes, contact your local government office.
What is stormwater?
As our towns and cities developed, we constructed roads, parking lots, homes, and driveways that disrupt the natural flow of water. When rain lands on these hard surfaces, it is not able to seep into the ground and instead becomes stormwater runoff. The runoff flows into our streets, enters the stormdrain, and travels through a network of pipes to the nearest waterway. This network of gutters, drains, and pipes is known as the stormwater system and is intended to prevent flooding. In rural areas, the stormwater system is generally made up of ditches and culvert pipes, rather than gutters and underground pipes.
What is the difference between a stormwater system and a sanitary sewer system?
In Minnesota, stormwater systems are a separate system of pipes/ditches and are not part of the sanitary sewer system that transports wastewater from our homes to the wastewater treatment facility. This is a very important concept to understand. Water that enters the stormwater system is transported to the nearest waterway without being treated at a wastewater treatment facility.
In rural areas, wastewater is typically piped to a below-ground individual septic treatment system.
How does storm water affect water quality?
An unintended consequence of the stormwater system is that pollutants such as automotive fluids, fertilizers and pesticides, bacteria, sediments, litter, and pet waste are quickly and efficiently transported from parking lots, roads, and driveways to the nearest waterway. Stormwater pollution results from many of our everyday activities such as how we care for and maintain our cars, lawns, and pets. The good news is that these are sources of pollution that we can do something about.
When we think about water pollution, many of us think of industry and wastewater treatment. While it is true that industry and wastewater treatment facilities can be a source of water pollution, these operations have made major improvements to their processes and have been regulated for many years. As a result, stormwater runoff from how we manage our landscape is now the most significant source of pollution to many of our local waterways.
It’s the condition of our local waters?
Minnesota State and many local municipalities and research institutions monitor and study our local waterways to determine if they are impaired for a specific pollutant. See state-verified polluted waterways.
For additional monitoring information, please contact your local government office.
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