Syphon Reservoir Improvement Project
10 Documents in Project
Summary
SCH Number
2019080009
Lead Agency
Irvine Ranch Water District
Document Title
Syphon Reservoir Improvement Project
Document Type
NOD - Notice of Determination
Received
Posted
10/29/2025
Document Description
The project would increase the capacity of the existing recycled water reservoir from
approximately 500 acre-feet (AF) to 5,000 AF. The project would replace the existing engineered dam with a new engineered dam, increasing the existing 59-foot dam height to 138 feet and increasing the elevation of the dam crest from the existing 388 feet above mean sea level (amsl) to 468 feet amsl. A new spillway would be included with the new dam to protect the reservoir from overtopping. As part of the new design, the engineered embankment dam would include a seepage control drainage system and a circulation/aeration system for the reservoir. The existing strainer and disinfection facilities would be demolished, reconstructed and expanded at the toe of the new dam to provide filtration, chlorination and de-chlorination. Additional project features include new onsite access and maintenance roads and wetland and riparian mitigation areas.
Environmental review of the potential impacts associated with the Syphon Reservoir Improvement Project Design Refinements has been completed, and Addendum No. 3 to the Syphon Reservoir Improvement Project’s Final Environmental Impact Report (FEIR) has been prepared. The purpose of Addendum No. 3 is to describe and evaluate the potential environmental effects associated with the Syphon Reservoir Improvement Project Design Refinements that involve refinements and nuances to the project in comparison to the preliminary design that was analyzed in the Syphon Reservoir Improvement Project FEIR. The FEIR determined that the project would not in any significant impacts. Addendum No. 3 describes and evaluates the potential environmental effects associated with the Syphon Reservoir Improvement Project Design Refinements pursuant to CEQA Guidelines Section 15164.
Contact Information
Name
Emily Le
Agency Name
Irvine Ranch Water District
Job Title
Environmental Compliance Analyst
Contact Types
Lead/Public Agency / Parties Undertaking Project
Phone
Email
Location
Coordinates
Cities
Irvine
Counties
Orange
Regions
Southern California
Cross Streets
Portola Parkway and Sand Canyon Avenue
Zip
92620
Total Acres
266
State Highways
SR 133, SR 241, SR 261
Schools
Stonegate Elementary, Crean Lutheran HS, Eastwood Elementary
Waterways
Syphon Reservoir, Bee Canyon Wash
Notice of Determination
Approving Agency
Irvine Ranch Water District
Approving Agency Role
Lead Agency
Approved On
County Clerk
Orange
Final Environmental Document Available at
15600 Sand Canyon Avenue, Irvine, CA 92618
Determinations
(1) The project will have a significant impact on the environment
No
(2a) An Environmental Impact Report was prepared for this project pursuant to the provisions of CEQA
Yes
(2b) A Mitigated or a Negative Declaration was prepared for this project pursuant to the provisions of CEQA
No
(2c) An other document type was prepared for this project pursuant to the provisions of CEQA
Yes (Addendum No. 3 to the Syphon Reservoir Improvement Project FEIR)
(3) Mitigated measures were made a condition of the approval of the project
Yes
(4) A mitigation reporting or monitoring plan was adopted for this project
Yes
(5) A Statement of Overriding Considerations was adopted for this project
No
(6) Findings were made pursuant to the provisions of CEQA
Yes
Attachments
Final Document(s) [Approved_Certified draft environmental documents]
Notice of Determination
Disclaimer: The Governor’s Office of Land Use and Climate Innovation (LCI) accepts no responsibility for the content or accessibility of these documents. To obtain an attachment in a different format, please contact the lead agency at the contact information listed above. For more information, please visit LCI’s Accessibility Site.