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

Vegetated Swales

Intercept & Treat Surface Water Runoff
View the Vegatated Swales signage placed at the reservoirs.

How Do They Work? 
Vegetated swales (also known as bioswales or biofilters) are sloped, low-lying areas designed to capture and treat storm water.

The swales collect stormwater runoff and allow it to soak into the ground at a slower rate.

Specialized native plants then help treat the stormwater by absorbing pollutants and filtering suspended sediments. This improves the quality of the surface water that enters the reservoir (or other bodies of water).

Bioswale Cross-section illustration below, or view the signage for a more detailed diagram and description of the process.

Bioswale Detail

You Can Work with Nature to Protect Stormwater:

  1. Keep it Cleaner
    • Hand pull or spot treat weeds to minimize chemical use
    • Replace high-maintenance turf grass with native perennials
    • Dispose of yard waster properly, never in a storm drain or stream
    • Keep oil, dirt, detergents and pesticides from entering storm drains
  2. Reduce the Flow
    • Minimize the use of impervious or hard, non-porpus surfaces
    • Maintain healthy vegetative buffers around waterways
    • Use rain berrels, rain gardens & bioswales to capture rain water


Great Blue Lobelia  Liatrus or Prairie Blazing Star   Cardinal Flower 

Native plants such as (left to right) the Great Blue Lobelia, Prairie Blazing Star (or Liatrus), and the Cardinal Flower work to filter contaminants from stormwater when used in bioswales and rain gardens.

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