Floodplains, RPAs, wetlands and stormwater across the DC area
What if my lot is in a floodplain, Resource Protection Area or wetland? The rules differ at every jurisdiction line. Here is the short answer for each.
Disclaimer: This is general information, not legal or professional advice for any one property. Codes change. SetbackIQ is not a zoning determination, a permit, or a survey, and it does not replace an architect, engineer, or lawyer. Confirm with your building and zoning offices before you build, buy, or sign a contract.
| Where | Short answer |
|---|---|
| Washington, DC | DC has no Virginia-style Resource Protection Areas. What it does regulate is soil disturbance (any work disturbing more than 50 sq ft needs an erosion and sediment control plan), stormwater for large projects, floodplains and wetlands. |
| Montgomery County, MD | Work in a mapped floodplain needs a floodplain district permit (County Code Ch. 19, Art. III). Stream valley buffers and wetlands are reviewed with sediment control permits. Montgomery has no Virginia-style RPA and no tidal Critical Area. |
| Prince George's County, MD | Lots within 1,000 ft of tidal water along the Patuxent and Potomac fall in the Chesapeake Bay Critical Area, which limits clearing and new impervious surface and protects a 100 ft buffer. SetbackIQ checks the state Critical Area map. |
| Alexandria, VA | Resource Protection Areas along the city's streams and the Potomac limit new building and paving. SetbackIQ checks the city's RPA map. |
| Arlington County, VA | Resource Protection Areas run 100 ft from streams, plus adjoining steep slopes. Inside one, almost any new outdoor work needs county review, and adding impervious cover needs an exception. SetbackIQ checks the county's RPA map. |
| Fairfax County, VA | Resource Protection Areas (the 100 ft buffers along streams), floodplains and grading are the big three. SetbackIQ checks the county's RPA map for your lot. |
Towns and cities inside these counties (for example, Rockville, Gaithersburg, Bowie, Laurel, Herndon, Vienna, and Falls Church) have their own rules.