INITIAL STUDY ASSESSMENT GUIDELINES (ISAGs)
COMPREHENSIVE UPDATE
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What's New?
Project Overview
Background
The California Environmental Quality Act, or CEQA, is the state law that requires public agencies, including the County of Ventura, to study and disclose potential environmental impacts of projects and adopt any feasible measures to reduce or eliminate those impacts before a project is approved.
One of the main goals of CEQA is to inform decision-makers and the public about potential environmental impacts of proposed projects. The County of Ventura carries out environmental review through local CEQA guidelines that are included in two documents: the Ventura County CEQA Implementation Manual (Implementation Manual) and the Ventura County Initial Study Assessment Guidelines (ISAGs).
The Implementation Manual and the ISAGs ensure that the County uses consistent procedures and evaluation criteria when examining the physical impacts of a public or private project on the environment. The ISAGs allow for a streamlined and transparent process for the public, project applicants, consultants, County staff, and decision-makers to review the environmental effects of a project.
The Project
The Implementation Manual was last updated in 2010 and the ISAGs were last updated in 2011. A comprehensive update to both documents is needed to align these documents with current County policies, CEQA requirements, and other state and federal regulations.
Public participation is a key element of the CEQA process. A public open house was held on May 7, 2025 and a public review period was open from April 24 – May 24, 2025. Revisions to the proposed updates were made in response to public comments received.
See below to learn more about the revisions.
Click here to learn more about the project (PDF).
Get Involved
The Board of Supervisiors will hold a public hearing to consider approval of (1) the proposed updates to the ISAGs, Noise and Vibration Assessment Guidelines, and Implementation Manual, (2) a related General Plan amendment, and (3) Addendum No. 3 to the General Plan Environmental Impact Report (SCH No. 2019011026). See below for details on the public hearing.
Board of Supervisors Hearing
September 30, 2025
1:00 p.m.
County Government Center
Hall of Administration
Board Hearing Room
800 S. Victoria Avenue, Ventura, CA 93009
Click here to learn how to participate or provide public comments.
Click here to view the hearing remotely.
The meeting agenda, along with the project materials, are anticipated to be available after 5:00 p.m. on Thursday, September 25, 2025. Click here to view the meeting agenda and meeting materials when they are available.
Spanish interpretation will be available at the hearing.
In compliance with the Americans with Disabilities Act, if you need assistance to participate in this meeting, you may obtain assistance by requesting such accommodation in writing addressed to the Clerk of the Board, 800 S. Victoria Avenue, Ventura, CA 93009, or by calling (805) 654-2251 at least 48 hours prior to the scheduled hearing.
Updated Initial Study Assessment Guidelines
The ISAGs inform the public, project applicants, consultants, and County staff on environmental impact thresholds and ways to determine whether a project has the potential to cause a significant negative effect on the environment. The ISAGs cover a wide range of topic areas, including air quality, transportation, water quality, biological resources, and many others listed below. Click here for an overview of the topic areas.
Key updates to the ISAGs include consolidation of sections of similar topics and removing certain sections, alignment with Appendix G in the State CEQA Guidelines, updated thresholds and methods for analyzing potential project impacts (including the Noise and Vibration Assessment Guidelines), and incorporation of certain General Plan programs and policies. Text revisions to some programs and policies are needed to improve clarity, reduce ambiguity, revise references, and where applicable, clarify County processes and procedures. These revisions are proposed as a General Plan Amendment.
Click here for a summary of the overall updates. Click on the following links to review the updated ISAGs or explore the updated topic areas individually below.
Proposed Updated Document
The initial draft of the updated ISAGs dated April 2025 was first released for public review from April 24 – May 24, 2025. Revisions were made in response to the public comments received and additional reviews conducted by County staff, which are included as markups in the second draft dated July 2025. The latest revised draft is dated September 2025 and it includes markups to identify changes from the previous drafts.
- Draft Updated ISAGs (September 2025)
- Draft Updated ISAGs (July 2025)
- Draft Updated ISAGs (April 2025)
- Existing ISAGs (April 2011)
Resources
Land Use
Hazards
Public Facilities/Services
Agriculture and Forestry Resources
Greenhouse Gases
Biological Resources
Beaches and Coastal Sand Dunes
Water Resources
Paleontological Resources
Mineral Resources
Historical Resources
Archaeological Resources
Tribal Cultural Resources
Land Use and Planning
Population and Housing
Aviation Hazards
Noise and Vibration
Geological Hazards
Wildfire Hazards
Hazardous Materials and Waste
Public Services
Utilities and Service Systems
Transportation
Updated CEQA Implementation Manual
The Implementation Manual was formerly titled the “Administrative Supplement to the State CEQA Guidelines.” The Implementation Manual includes procedures to comply with CEQA, such as filing public notices of proposed projects. Key updates to the Implementation Manual include updated CEQA requirements, procedures to amend the document in the future, and County agency responsibilities.
The initial draft of the updated Implementation Manual dated April 2025 was first released for public review from April 24 – May 24, 2025. Revisions were made in response to the public comments received, which are included as markups in the second draft dated July 2025. The latest revised draft is dated September 2025 and it includes markups to identify changes from the previous drafts.
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Contact Us
Inquiries may be directed to Case Planner, Jessica Nguyen, at (805) 654-5037 or by e-mail to ISAGS@venturacounty.gov