Stormwater management refers to the development of effective programs and policies that preserve or enhance the quality of stormwater runoff, control the quantity of stormwater runoff, reduce erosion and prevent flooding.  Prior to the year 1990, stormwater management focused on controlling the quantity of runoff from urban and developing areas.  Today, localities are concerned with the quality of stromwater runoff as well. 

Why Stormwater Management?

Urban runoff is considered a major source of nonpoint pollution.  Scientists estimate that more than half of the pollutants entering our waterways are carried by stormwater runoff.  Increased water quantity resulting from stormwater runoff can have devastating effects on neighborhood properties. 

Where Should Stormwater Management be Considered?

Stormwater management should be a consideration on every site regardless of size or intended use.  The measure and complexity used to control stormwater will vary from site to site.

When Should Stormwater Management be Considered?

Stormwater management should begin as soon as development begins, and should remain a concern long after development is completed.

Best Management Practice (BMP)

A method, activity, maintenance procedure, or other management practice from reducing the amount of pollution entering a waterbody.  BMPs generally fall into two categories: source control BMPs and stormwater management BMPs.  The term originated from the rules and regulations developed pursuant to section 208 of the Federal Clean Water Act (40 CFR 130).

Detention

The temporary holding of stormwater from a site, with release at a slower rate than it is collected by a drainage facility system.

Erosion

The wearing away of land surface by wind or water.  Erosion occurs naturally from weather or runoff but can be intensified by land-clearing practices.

Impervious surface

A hard surface area that either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development, and/or a hard surface area that causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development.

Retention/Detention (R/D) facility

A type of drainage facility designed (1) to hold runoff for a considerable length of time and then release it by evaporation, plant transpiration, and/or infiltration into the ground or (2) to hold runoff for a short period of time and then release it to the surface and stormwater system.  Most facilities do both to some degree.

Not all stormwater management requires additional engineering or increased development costs.

• Limiting the amount of impervious surface in new and retrofitted development
• Creating setbacks from surface water and wetlands
• Use of best management practices
• Consider using alternative paving materials such as bricks, flagstone, sand or gravel in the construction of driveways and walkways
• Redirect downspouts so they are not aimed at a paved surface
• Grass swales rather than curb/gutters

• Also, where possible, grade land to form swales and berms to intercept runoff and allow it to infiltrate the soil
• Angles parking with one way traffic flow
• Smaller parking stalls
• Reduced parking space ratios
• Shared parking facilities in commercial areas
• Permeable spillover parking areas
• Limit clearing and erosion during construction