Los Angeles County Department of Regional Planning


SEA Program - Background Information

1970 Open Space Concept (Schematic or Sketch Map)

1970 Open Space Concept Plan

The identification of important biological resources and preservation of Significant Ecological Areas (SEAs) has a long standing history in Los Angeles County. In 1970, the County adopted the Environmental Development Guide, which contains a schematic map called the Open Space Concept Plan. This map depicts areas thought to be of significance for both conservation and safety in 1970 and closely resembles the current proposed SEA Map.


1972 Environmental Resource Committee

In 1972, the Environmental Resource Committee of the Southern California Academy of Sciences and members of the UCLA botany and zoology faculties prepared an environmental resources survey for the County. The survey identifies areas throughout the County that warrant special consideration, due to their high biological resource value. Eighty-one (81) of these areas were identified on the vegetation and wildlife map in the 1973 Los Angeles County General Plan.


1976 Significant Ecological Areas Study

In 1976, the Los Angeles County Significant Ecological Areas Study was conducted to reevaluate the areas identified by the Environmental Resource Committee in 1972. During this detailed study 115 areas were identified as possible SEAs. Ultimately, 62 of the most significant areas where recommended as SEAs, in an effort to protect the full range of biological diversity in Los Angeles County.


1980 Significant Ecological Areas

In 1980, 61 of the Significant Ecological Areas identified in the 1976 Study were adopted as part of the Conservation and Open Space Element of the Los Angeles County General Plan. These SEAs were islands of significant habitats within larger undeveloped areas, which were thought to provide sensitive plants and animals ample open space and ensure their continued existence. Since 1980 however, many of the resources within these areas were impacted by development activity within and around the SEA boundaries. Because some of the “island” habitats were isolated from each other by development within the intervening areas, the opportunity for species movement and genetic dissemination was dramatically reduced. Therefore, the identification of island habitats, independent of the entire ecosystem, was ultimately deemed to be unsustainable.


1982 & 1991 Supplemental Studies

Supplemental studies further assessing the biological resources within thirteen SEAs were conducted in 1982 and 1991. These studies occurred in the Santa Monica Mountains, San Gabriel Canyon, Chino Hills, San Francisquito Canyon and Kentucky Springs. Each study determined that either the SEA boundaries adequately encompass the specific species identified in the SEA description or recommended the expansion of the boundaries to better encompass the resources.


2000 SEA Study Update Study

In 1999, the County began a comprehensive revision to the 1980 Countywide General Plan. As part of this revision, a study of the SEAs was commissioned and in January 2001 the Los Angeles County Significant Ecological Area Update Study 2000 was released for public review. Conservation planning was a fundamental aspect of this Study, which was designed to accomplish the following: evaluate existing SEAs for changes in biotic conditions and consider additional areas for SEA status; propose SEA boundaries based upon biotic evaluation; and propose guidelines for managing and conserving biological resources within SEAs. The SEA Update Study 2000 was based on scientifically grounded concepts regarding the size and type of linkage systems necessary to sustain the biologically diverse plant and animal species that are found within the County. All recommended SEAs in the SEA Update Study were evaluated and refined between 2001 and 2002 after consideration of public and resource agency input.


2002 Draft General Plan Initial Study

In 2002, a proposed SEA Map was released for public review as part of the Comprehensive Update and Amendment to the Los Angeles County General Plan (Initial Study).


2003 Draft General Plan Policy Document

In 2003, following the General Plan’s Initial Study, the County released a Draft General Plan policy and map document called Shaping the Future 2025. The draft SEA Map in Shaping the Future reflected changes to the proposed SEAs based on biological information and public input received during the draft General Plan Initial Study public review period.


2005-2007 Draft SEA Map

In 2005, the proposed SEAs were again refined, based on the SEA criteria, to address public comment received in 2003 and 2004. Additional field work was conducted, literature review and sensitive species data tables updated, and a subset of the SEAs, called Ecological Transition Areas, identified and mapped. At the end of this process, the County’s staff biologists and environmental consultants convened to review the updated SEA boundaries over aerial photography to ensure mapping accuracy. The meeting resulted in all four biologists concurring that the proposed boundaries met the SEA criteria. These refinements were reflected on the draft SEA Map, released for public review as part of the draft General Plan in 2007.


2008 Draft SEA Map

In 2008, the draft SEA Map was released for public review as part of the draft General Plan.


2010 Expert Panel of Biologists

In 2010, an expert panel of biologists was convened to evaluate the SEA boundaries. The panel reviewed the SEA criteria, discussed scientific data, current biological theory, and their knowledge of the resources. Based on the SEA criteria and program methodology, additional locations were identified as areas that warranted the SEA designation. There were no recommendations to reduce the SEA boundaries. All recommendations by the panel to the County were considered and many were incorporated into the SEA Program.


2015 Adopted SEA Map

In 2015, the Board of Supervisors approved both the Antelope Valley Area Plan and the General Plan 2035, which created the final boundaries and categories for the SEAs. The boundary changes adopted by the Antelope Valley Area Plan were effective on June 16th, 2015; the remaining boundary changes adopted by the General Plan 2035 were effective as of November 5th, 2015. Please click on the following link to view the modifications to the SEA boundaries and categories between the years 2013 and 2015.


1970s & 1980s

1991 Supplemental Studies

2000 SEA Update Study

DRP en Español

Online Appointment Now Available!

Metro Area Plan Outdoor Permit Covid-19 UAS Drone Housing Element Update SB 9 Oil Well Tree Pest Disease FFCP Homeless Buying Property SEATAC Historic Preservation DRP Video Library

Follow Us

Twitter Facebook Instagram YouTube

©2009 Los Angeles County Department of Regional Planning.

All Rights Reserved. Terms under which this service is provided to you. Privacy Statement.

Please send website questions and comments to webadmin@planning.lacounty.gov

Many of our documents are in PDF format. You can download Adobe Reader by clicking this link.

Department of Regional Planning
320 West Temple Street
Los Angeles, CA 90012
T: (213) 974-6411 . F: (213) 626-0434
TDD: (213) 617-2292
Twitter Facebook Instagram YouTube