Syphon Reservoir Improvement Project
9 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
5/14/2025
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 136 feet and increasing the elevation of the dam crest from the existing 388 feet above mean sea level (amsl) to 466 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 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 and disinfection. Additional project features include new onsite access and maintenance roads; on-site and off-site wetland and riparian mitigation areas; and potential recreational facilities.
Environmental review of the potential impacts associated with the change in status of Crotch’s bumble bee (Bombus crotchii; CBB) to candidate for listing under the California Endangered Species Act (CESA) has been completed, and Addendum No. 2 to the Syphon Reservoir Improvement Project’s Final Environmental Impact Report (FEIR) has been prepared. At the time the FEIR was certified in 2021, CBB was not a candidate for listing under CESA. In 2022, after the FEIR was certified, CBB became a candidate for State listing under CESA. The FEIR determined that construction of the expanded reservoir would temporarily remove and permanently displace native and non-native upland habitat and disturbed land cover around the reservoir, including various types of coastal sage scrub (CSS), which may serve as suitable foraging and nesting habitat for CBB. The purpose of Addendum No. 2 is to describe and evaluate the potential environmental effects associated with the change in listing status of CBB pursuant to CEQA Guidelines Section 15164.
Contact Information
Name
Fiona Sanchez
Agency Name
Irvine Ranch Water District
Job Title
Director of Water Resources
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
Parcel #
104-117-40, 104-117-27, 104-117-42
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. 2 to 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
Notice of Determination
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