What is Stormwater Runoff?
When the amount of rain falling exceeds the land's ability to absorb it, the result is stormwater runoff. Stormwater runoff collects when water from rain or snowmelt comes into contact with an impervious or semi-impervious surface like a driveway, rooftop, parking lot, gravel road, or area of compacted soil. These surfaces prevent water from naturally soaking into the ground and as a result, the amount and speed of water travelling across the land’s surface increases.


Why is it a problem? There can be a lot of it and what it carries.
The excess water from rain storms that is not absorbed into the ground instead ends up in our rivers and streams. A short light rain falling on permeable soils might produce little to no runoff, while heavy rain landing on an impervious street or parking lot can produce a substantial amount. The volume of stormwater can be a problem when high amounts of water cause flooding and erosion of stream banks.

As water runs over the landscape it can pick up pollutants such as oil, debris, chemicals, nutrients, sediment and bacteria along the way. This pollutant rich water often flows directly to a lake, stream, river or wetland and in some cases it may be caught by a municipal stormwater system. However, the result is the same, anything that enters the stormwater system is discharged untreated into the waterways we use for swimming, fishing and providing drinking water.


How Can I Help?
Oftentimes, minor practical changes to our daily habits can help keep pollutants out of our stormwater and local waterways. These are called Best Management Practices (BMPs), to take action, find out more about the causes and solutions of stormwater pollution.

Footer termsofuseprivacypolicytermsofuseprivacypolicy steeringcommittee termsofuseprivacypolicy