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Blue-Line Streams

What is a Blue-Line Stream?

A blue-line stream is any stream shown as a solid or broken blue line on 7.5 Minute Series quadrangle maps prepared by the U.S. Department of the Interior Geological Survey (USGS). A blue-line stream is a body of concentrated flowing water in a natural low are or natural channel on the land surface and may be any creek, stream or other flowing water feature, perennial or ephemeral, indicated on USGS quadrangle maps, with the exception of man-made watercourses. Such a designation probably is based simply on aerial photographs showing channel vegetation, but so far as the USGS is concerned, they have no specific hydrologic or biologic significance. Therefore, the blue-line stream has no rational relationship to recognized planning concerns.

Blue-line streams are not regulated by the District. Flood Hazard Areas included in Ordinance No. 458 and shown on the District’s Interactive Map are regulated by the District.

Why are Blue-Line Streams Important?

The United States Army Corps of Engineers uses USGS blue-line stream markings as a preliminary indicator of “Waters of the United States”. Streams identified on USGS maps in such a manner are therefore generally subject to federal environmental regulations. A blue-line stream may or may not be a mapped flood hazard area. Streams do not have to be “blue-line” or appear on a map to be considered waters of the United State and regulated.

What are my Setback Requirements?

There is no standard setback requirement for development. Contact U.S. Army Corps of Engineers and California Department of Fish and Wildlife for permit and setback requirements. Stream channels worthy of protection need to be defined based on such hydrologic variables as stream order, gradient, bed width, tributary area, groundwater recharge, vegetative species, and hydraulics, and certainly not blue ink.

How do I get Blue-Line Stream Information?

Riverside County Map My County Interactive Map includes blue-line streams from the USGS Quad Maps.

Whom do I contact regarding permits for building in or around a Blue Line Stream?

The U.S. Army Corps of Engineers determine the presence and location of wetlands that are jurisdictional under Section 404 of the Clean Water Act.

U.S. Army Corps of Engineers
Los Angeles District, U.S. Army Corps of Engineers
Regulatory Division
915 Wilshire Blvd., Suite 930
Los Angeles, CA 90017
Electron submittals for Orange County, Riverside County, Special Area Management Plans
South Coast Branch/Orange and Riverside Counties Team
Phone: 213.452.3425
Email: [email protected]


The California Department of Fish and Wildlife determine the presence and location of species and habitat that are jurisdictional under Fish and Game Code Sections 1600-1607.

California Department of Fish and Wildlife
3602 Inland Empire Blvd, Suite C-220
Ontario, CA 91764-4913
Use online permitting portal.
Questions send to [email protected]

The Regional Water Quality Control Boards may need to issue a 401 Water Quality Certification if the stream is jurisdictional under Section 401 or Waste Discharge Requirements for impacts to Waters of the State that are not regulated by U.S. Army Corps of Engineers. To determine which watershed or which Regional Board to contact use this web map:

Santa Ana River Regional Water Quality Board (Northwestern Riverside County)
3737 Main Street, Suite 500
Riverside, CA 92501-3348

San Diego Regional Water Quality Board (Temecula, Murrieta, Wildomar, and Anza areas)
2375 Northside Drive, Suite 100
San Diego, CA 92108

Colorado River Basin Regional Water Quality Board (All parts of Riverside County east of Beaumont/Banning)
73-720 Fred Waring Dr., Suite 100
Palm Desert, CA 92260

How long do Regulatory Permits take?

Regulatory permits through U.S. Army Corps of Engineers and California Department of Fish and Wildlife can take 6 months to a year to process from the time they are received. Contact U.S. Army Corps of Engineers and California Department of Fish and Wildlife directly for a specific timeframe.