A floodplain is an integral part of the stream system. It provides storage capacity for high flows, helps reduce the erosive power of the stream during a flood, reduces the discharge of sediment during high flow periods and helps flood waters to move downstream. Floodplains also offer opportunities for wildlife habitat which can increase the biotic diversity of a stream. The 100-year floodplain is that land area adjoining the stream that has a 1% or greater probability of flooding in any given year. Floodplains provide a stream with buffer and water quality benefits as well.

Floodplain Policy

It is the policy of the Prince George's County Government to preserve the 100-year floodplain as part of the natural system of a stream, and to further preserve it in a natural state in order to provide adequate storage for flood waters and sufficient carrying capacity to safely move flood waters downstream. Where existing structures in the 100-year floodplain cannot be protected in an environmentally sensitive and cost effective manner, the county may offer to acquire them to reduce the potential for property damage and eliminate potential obstruction of flood waters.

Future development is regulated within the ultimate 100-year floodplain. Prince George's County utilizes ultimate land-use conditions hydrology to determine flood discharges and to generate flood elevations for areas of the county under growth and development. Ultimate conditions hydrology reflects projected land-use conditions based on a community’s zoning maps and/or comprehensive land-use plans.

Prince George's County has, through the Maryland-National Capital Park and Planning Commission, established a policy to acquire stream valley parks throughout the county. Stream valley park acquisition permits public ownership of the floodplain, thus eliminating pressure for private development and providing recreational opportunities. Stream valley parks will continue to be an important component of the county’s recreation, open space and flood management programs.

Flood Management Goals

• Improve the quality of life in Prince George's County.
• Prevent future flood hazards from developing.
• Provide for expanded recreational and aesthetic opportunities in the county.
• Reduce or eliminate existing flood hazards.
• Reduce the economic losses associated with flooding events.
• Restore, preserve and enhance environmental quality wherever possible.

The Floodplain Ordinance was adopted by the County Council in April of 1989 and amended in 1993, 2000, 2011 and 2016. The Prince George's County Floodplain Ordinance is modeled after an ordinance suggested by the Maryland Department of the Environment (MDE). The Federal Emergency Management Agency (FEMA) contracted with MDE to review local floodplain ordinances to assure that they met FEMA requirements for eligibility for flood insurance.

Filling/Construction in the Floodplain

The ordinance generally discourages filling or construction in the floodplain, but allows for a variance under certain circumstances, for example, to meet an important public need. Where filling is needed within the floodplain, an equal volume of compensatory storage must be provided. Furthermore, an impact study is needed to ensure that the floodplain elevation will not be increased. The ordinance also contains requirements for the protection of buffers, wetlands and other natural features associated with the floodplain.

National Flood Insurance Program

Prince George's County has been participating in FEMA’s National Flood Insurance Program (NFIP) since 1972. The current effective Flood Insurance Rate Map (FIRM) can be reached by visiting the FEMA Floodplain Map of Prince George's County.