Summer drought? Not on Southeast Michigan freeways

Heavy rains recently closed freeways due to flooding. Why does this occur and what can individuals do to reduce stormwater flooding?

In southeast Michigan, there are tens of thousands of storm sewers or drains. If you look along any road, whether it’s a residential street, freeway or even parking lot, there are grated storm sewers that rid our streets of excess water. While each storm drain may only contribute a small amount of water and possible pollution, if multiplied by all those thousands of drains, it adds up to a vast quantity of water and pollution. A common misconception is that these storm sewers carry the excess water to a wastewater treatment plant for cleaning. This is not the case. These storm drains take the water away from the pavement and transport it to the nearest stream, river or lake.

This stormwater often contains contaminants found on these paved surfaces, including gasoline and oil, antifreeze, pet waste, fertilizers, pesticides, litter, leaves and grass clippings. The last three are partially to blame for the temporary closing of I-696 and I-94 last week. Debris covered the storm grates and water could not get into the drains and off the road.

What can individuals do to prevent these contaminants from getting into stormwater and clogging drains or polluting local waterways?

First, remember anything left on the ground, thrown out of a car onto the road or applied to grass can pollute local rivers, streams and lakes.

Do not allow leaves, grass, soil or other debris to accumulate on the driveway, sidewalk or in the street. These will get swept up in stormwater and either clog the storm drain or pass through and into the local water body where it can pollute it. Grass is particularly bad since it contains nitrogen which feeds aquatic plant life.

Do not put any chemical down a storm drain, such as used motor oil, paint, antifreeze or solvents. These pollute the water and may be toxic to fish and other wildlife.

Sweep or blow any fertilizer or pesticide applied to lawn surfaces back onto the lawn. Michigan law requires that you do this.

Pick up after your pet. Carry a bag to collect pet waste to take home to bury or flush down the toilet. Leaving this waste on the sidewalk or lawn allow it to be mixed with rain water during the next rain event.

Contact your local community to find out what actions they have implemented to reduce contaminants from stormwater. This might include more frequent street sweeping (for example semi-annually instead of annually), adopting and enforcing soil erosion controls at construction sites, or adopting stormwater controls in new and/or existing areas that have potential for significant runoff.

For more information on managing stormwater, visit Michigan State University Extension.

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