What is considered "Impervious" or "Pervious"?

Areas identified as impervious

  • Hardened surfaces on or near the ground: sidewalks, private roads, private streets, parking lots, walkways, patios, concrete slabs, runways, taxiways, aprons, or other hardened surfaces consisting of asphalt, concrete, or other paving material
  • Hardened surfaces above ground: buildings, foundations, storage tanks, rooftops, athletic courts, and tracks 
  • Gravel and dirt driveways and pavers that do not meet requirements to be classified as pervious
  • Paved decks adjacent to pools 
  • Wooden decks covered by a roof or having an impervious underlying surface
  • Surface water that is not part of the public conveyance system

Areas identified as pervious

  • grass 
  • gardens 
  • landscaped areas without impervious underlying membrane 
  • natural rock formations 
  • dirt paths 
  • pavers set in porous fill (photos, design plans, and specifications must be submitted) 
  • porous pavements (photos, design plans, and specifications must be submitted)

Pervious Surface versus Hard Surface


Show All Answers

1. What is a stormwater utility fee?
2. Why is stormwater run-off a problem?
3. Why should I have to pay for rain falling on my property
4. Why did the city stop charging a stormwater fee and but now is charging a new fee?
5. Why is this fee higher than the fee that was previously charged?
6. What is my stormwater fee based upon?
7. What is considered "Impervious" or "Pervious"?
8. How were the impervious surfaces measured on my property?
9. Are roads and public rights-of-way charged the stormwater utility fee?
10. What does the stormwater program do?
11. How accurate are the impervious are analysis images that can be found online?
12. What credits are available to residential property owners?
13. What if I was overcharged or I successfully appealed the measured impervious area?