The Chesapeake Bay Preservation Ordinance was adopted to protect our local streams and one of the world's most productive estuaries, the Chesapeake Bay, from pollution due to land use and development. All of Fairfax County drains into the Potomac River and ultimately the Chesapeake Bay. In an effort to protect and improve the quality of these waterways, sensitive areas along streams throughout Fairfax County have been designated as Resource Protection Areas.

State regulations require that Resource Protection Areas (RPAs) be designated around all water bodies with perennial flow. Perennial flow means that water always flows in the stream or other water body except during periods of drought. The Department of Public Works and Environmental Services conducted field studies to identify all perennial streams throughout the county and used this information to prepare a set of maps showing the location of RPAs as defined under the revised Ordinance. The maps were adopted by the Board on November 17, 2003. 

The data include the boundaries of the RPAs adopted by the Board in 1993 and the additional RPAs adopted by the Board in 2003. These are general locations of RPA boundaries for planning purposes and the actual limits may be further refined by detailed field studies conducted at the time a plan is submitted to obtain a permit to develop a property.

Any areas within Fairfax County not contained within the RPAs are Resource Management Areas (RMAs). Together, the RPAs and RMAs comprise the Chesapeake Bay Preservation Areas.