Keep It Clean

    Hoover Crop  

Simple steps you can take at home to  prevent water pollution .

Take a Tour

Watershed Signage

Signage installed at Griggs, O'Shaughnessy & Hoover Reservoirs invites park visitors to  take a self-guided tour along the shoreline & learn about the green infrastructure installed there.

Rain gardens, porous pavement & more can improve the quality of storm water entering the reservoirs that supply our drinking water.

Non-point Source Pollution

Stormwater Runoff

Protect our Waterways
Illustration Courtesy of NCDENR

Bioretention Systems

Bioretention Systems Collect & Filter Stormwater Runoff
View the signage placed at the reservoirs.

How Do They Work?

Illustrated below, bioretention systems treat stormwater naturally by collecting runoff, allowing it to absorb into the ground at a slower rate, and reducing peak runoff volumes. 

Specialized native plants take in excess nutrients and filter out suspended sediments, improving the quality of surface water entering the reservoir (or other bodies of water).

You Can Help Protect Stormwater

  • Minimize use of hard & paved surfaces
  • Use rain barrels, rain gardens & bioswales to capture the flow
  • Maintain healthy vegetated buffers around waterways
  • Keep oil, dirt, detergents, lawn chemical
  • Visit 'Keep it Clean' or  We All Live Downstream  to learn more

Map 120 AcresIllustrations:

A 3/4" rainfall in this 120 acre area near Griggs Reservoir (map) can amount to 1.22 million gallons of stormwater. 


The stormwater flowing from the surrounding neighborhood enters the bioretention basins through an outflow pipe (photo). 


Outflow PipeIt then drains into 4 bioretention basins illustrated below.


For a more detailed view and additional illustrations,  view the Bioretention systems signage

  Bioretention Basin Illustration