What is Stormwater?
As the County has become more developed, we’ve replaced our natural landscapes with asphalt, concrete, buildings and roadways. Before development, when it rained or snowed, the resulting water runoff would be naturally absorbed into the soil or flow over the ground to a nearby stream. Development has disrupted this natural cycle of water flow.
During rain and snow storms, runoff can pick up substances like oil, grease, litter, pesticides, or fertilizers and become polluted. The polluted runoff (commonly called stormwater runoff) carries these substances as it flows into our streams, lakes, ponds and rivers making them unhealthy.
Most of the stormwater runoff from roads, driveways, rooftops, and parking lots is not treated before it reaches our waterways. Urban stormwater runoff is the only major source of pollution that is increasing.
There are two major concerns with stormwater runoff.
The timing of the runoff and the amount or volume of the runoff.
Pollutants contained within the runoff. Examples include:
An impervious surface is any surface in which water is unable to penetrate. These hard surfaces interfere with the natural drainage patterns for local waterways. Common surfaces that are considered impervious include:
There are many other examples but water that falls on these surfaces is unable to soak into them. When there is no place for the water to soak into the ground, the water accumulates and flows across these surfaces with increased momentum. As the water concentrates, it moves faster and faster across the land, similar to a “snowball effect”. Depending on the volume, once this concentrated, fast-moving water flows off of these surfaces or reaches streams, flooding, heavy erosion or other devastating impacts can occur.
In an ideal natural environment without development, 10% or less of the water typically runs off the land. In highly developed or impervious areas, over 30% of the water may run off the land.
This increased runoff has led to many land planning and development challenges. Even though Montgomery County has required stormwater management since the 1970's, there are many older developments without it. Today, stormwater is regulated on the State and Federal government level through the Stormwater Permit program and local governments like Montgomery County face a daunting task in implementing stormwater reduction and improvement programs.
Do you contribute to stormwater runoff?
Note: One inch of rain that falls over 1 square feet of impervious surface creates .6 gallons of water.
So a roof of 2100 square feet would produce 1260 gallons of water per 1 inch storm.
2100 x .6 gallons = 1260 gallons!!!
Find out how you can reduce the runoff on your property.
Help Prevent Stormwater Runoff
Everyone has a part to play in preventing stormwater runoff. The easiest way to minimize stormwater runoff is to leave land undeveloped, especially near streams.
Take Advantage of County Resources (and Financial Incentives)
Along with the satisfaction of helping to prevent pollution, erosion and stream damage, there are other benefits to helping to prevent stormwater runoff.
How Does the County Manage Stormwater?
The County uses several approaches to best manage stormwater and polluted runoff. Properly managing this volume and runoff involves a large coordinated effort that includes several agencies.
The Department of Environmental Protection (DEP) handles many of the programs that assess and address existing impacts from stormwater and water pollution. It is also the lead agency for coordination and reporting related to the County's Stormwater Permit. These programs include:
Along with administering these programs, the DEP coordinates with several other County agencies to reduce the impact from stormwater and polluted runoff.
Outside of these efforts, there are several other agencies in Montgomery County that administer programs focused on reducing stormwater pollution in our streams.
While these agency’s environmental programs contribute significantly to reducing stormwater pollution in our streams, their protection and ability to thrive ultimately starts with our residents. Find out how you, your family and neighbors can help reduce stormwater impacts in your community.
Human Health and Drinking Water Concerns
In the more urban and suburban areas of Montgomery County, the water from the faucets in your home or business is piped from a water filtration plant operated by one of the local water providers. The County's public water supply comes from the Potomac River or the Patuxent River. The source water from those rivers goes through a filtration and treatment process to ensure that it meets federal drinking water standards.
In the western and northern areas of the County, many areas are served by private wells. In those areas, it is up to residents to periodically test their drinking water to assure that no contamination is occurring.
The Water Supply and Wastewater section of the DEP website has additional information on how public water and septic systems are managed and how water gets to our homes.