Natural and Beneficial Functions of Floodplains

When portions of floodplains are preserved or restored to their natural state, they provide many benefits to both human and natural systems.  Open space resource areas adjacent to floodplain areas increase aesthetics and recreational opportunities; reduce the number and severity of floods, help handle stormwater run-off and minimize non-point water pollution.

The County of San Diego General Plan sets forth the following objectives to conserve resources and natural processes:

  • Encourage the preservation of the significant natural features of the County, including lakes, basins, river banks and waterways.
  • Encourage only those uses and activities that are compatible with the marine ecosystem along the shoreline. Designate appropriate areas as underwater or water-related wildlife preserves.
  • Discourage any use of the lagoons that would be incompatible with their natural ecosystems.
  • Encourage the conservation of vegetation and trees needed to prevent erosion, siltation, flood, and drought, and to protect air and water quality.

Objectives under the health and safety goal include:

  • Protect life and property by regulating uses in areas subject to flooding.
  • Reduce the need for the construction of major flood control improvements.
  • Control development to assure a minimal adverse polluting effect on reservoirs, lakes, streams, rivers and groundwater supplies.   

In accordance with policies set forth in the County of San Diego General Plan, a large proportion of floodplains within the County are held for open space uses, such as parks and other recreational areas, many in a natural or beneficial state. The County's Multiple Species Conservation Program (MSCP) further ensures that the objectives of the General Plan are met.  The MSCP goals are to maintain and enhance biological diversity in the region; to maintain viable populations of endangered, threatened, and key sensitive species and their habitats, and to protect water quality. Through the MSCP, key habitat areas have been acquired. The first properties acquired were the Ham and Yunis properties in the Lakeside Archipelago area in January 1999.  The two properties totaled nearly 60 acres.  County-approved MSCP properties now total more than 4,500 acres.

The County of San Diego Watershed Protection, Stormwater Management, and Discharge Control Ordinance requires measures to control flow rates and velocities so that flows and flow patterns do not disrupt downstream wetlands or riparian habitats.  Diversion of runoff to regional facilities is not allowed if it will deprive immediate downstream habitats of the minimum flows and /or over-bank flow events they need.

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If you have questions or would like additional information, 
call the County Stormwater hotline at 1(888) 846-0800
or e-mail us at

Report a Stormwater Violation On-Line

If you see a County storm drainage system in need of maintenance, contact the County Department of Public Works Field Operations staff at (619) 443-1260 weekdays or contact the Stormwater Hotline at 1(888) 846-0800.  For after-hours emergencies contact (858) 565-5262. 

Department of Public Works
Flood Control
5510 Overland Ave., Suite 410, MS O326
San Diego,  CA  92123,  USA
(858) 495-5318           Fax: (858) 495-5263