When our forefathers came to the United States they navigated many streams, lakes, and rivers as they explored and settled the continent. When they camped, they thought nothing of taking a bucketful of water from a nearby stream and drinking from it, cooking with it, or bathing in it. No thought was given to pollutants. Today our world is much different. Our natural water supplies are filled with pollutants. Water has to be treated and purified before we can drink it.
Though we may never be able to restore our water supplies to their natural state, there are steps that can be taken to prevent further pollution and degradation. One such step is to control “stormwater runoff.” It has been cited as a major pollutant in Indiana’s waterways, and the State of Indiana recently passed regulations to control it.
What is “stormwater runoff”?
Stormwater occurs naturally when it rains or snows. It’s part of the hydrologic cycle – the distribution and movement of water between the earth’s atmosphere, land, and water bodies. Stormwater runoff includes rainfall, snowmelt, and other forms of precipitation that falls to the earth’s surface. When precipitation reaches the earth’s surface, it can either infiltrate into the natural landscape or runoff. Which one it does depends a great deal on land use. Normally, runoff will be less from a forested landscape than that from an urbanized landscape.
What happens when stormwater “runs off”?
According to the Enviromental Protection Agency (EPA), “When it rains or snows, the water that runs off of city streets, parking lots, and construction sites can wash sediment, oil, grease, toxics, pathogens, and other pollutants into nearby storm drains. Once this pollution has entered the sewer system, it is discharged-(usually) untreated-into local streams and waterways. Knows as stormwater runoff, this pollution is a leading threat to public health and the environment today.”
In developed areas, where much of the land surface is covered by buildings and pavement, water cannot soak into the ground. As a result, the stormwater flows over these impervious surfaces and picks up many toxic chemicals from motor oil, lead from gas and auto exhaust, and zinc from roof drains and tires. These chemicals may kill or impair the health of aquatic life.
Stormwater may also contain sediment (soil particles) if it is washed off construction sites. When sediment enters a lake or stream, the water appears cloudy or turbid. Over time, it will fill in a stream or lake as it settles out of the water. Phosphorus is a nutrient often attached to soil particles that fuels the growth of algae and aquatic weeds, plants that are important as fish and wildlife habitat. Too much phosphorus, however, can cause rapid and excessive growth of the plants and can degrade water quality, and interfere with swimming, boating, and fishing.
Bacteria, viruses, and other disease causing microorganisms can abound in stormwater that carries pet waste and litter. They make waterways unsafe for swimming and other types of water recreation. People who depend on lakes or streams for drinking water may be endangered because some microorganisms are difficult to remove through water treatment. Other potential stormwater pollutants include fertilizer, pesticides, leaves, and grass clippings.
Polluted stormwater runoff is also called “nonpoint source” (cannot be traced to a single source) pollution. Water running off your yard, sidewalk or street flows down to the curb and into the nearest storm drain. From there, it flows into the storm drain system, a vast network of underground pipes and tunnels that carry it to nearby streams and lakes. Contrary to popular belief, stormwater normally does NOT go to the sewage treatment plant.