Clear Lake Hypolimnetic Oxygenation System (HOS)
Summary
SCH Number
2026050932
Public Agency
University of California, Davis
Document Title
Clear Lake Hypolimnetic Oxygenation System (HOS)
Document Type
NOE - Notice of Exemption
Received
Posted
5/22/2026
Document Description
UC Davis proposes the Clear Lake Hypolimnetic Oxygenation System (HOS) project, a pilot water quality treatment that delivers oxygen to the bottom layer of water at Clear Lake during periods of low oxygen. The HOS includes both land and lake components. The land components include a 15,000- gallon liquid oxygen tank on a curbed 25 x 25 ft concrete pad, refill hose and splash pad, evaporator, controls, piping, and discharge manifold. Land components of the HOS will be installed at the Clearlake Oaks County Water District property adjacent to the lake. A pipeline will deliver the compressed oxygen gas along the treatment plant’s pier paralleling the plant’s intake pipes into the lake. The in-lake components include two pipelines of approximately 20,000 linear feet reaching from the pier around the west end of Rattlesnake Island and into the deepest part of Oaks Arm where the diffusion takes place. The pipeline will be anchored with approximately 2,000 concrete blocks and rest on top of the lakebed. The in-lake portion will connect to the onshore pipeline at the water treatment plant pier, avoiding any construction impacts to the lake shore. The project also includes security fencing, lighting for on-land components, and installation of solar panels to power the system.
Contact Information
Name
Heather Davis
Agency Name
UC Davis
Job Title
Director, Campus and Environmental Planning
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project
Phone
Email
Location
Cities
Unicorporated - Lake County, Clearlake Oaks area
Counties
Lake
Regions
Countywide, Unincorporated
Cross Streets
E Hwy 20 and Island Drive
Zip
95423
Parcel #
035-111-30
State Highways
HWY 20
Waterways
Clear Lake
Other Location Info
Clearlake Oaks arm of Clear Lake. On-shore components would be located at Clearlake Oaks County Water District facility (12525 E State Hwy 20, Clearlake Oaks)
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Class 3 (15303), Class 4 (15304), Class 6 (15306), Class 8 (15308)
Reasons for Exemption
The project is categorically exempt under Class 3, Class, 4, Class 6 and Class 8 of the Guidelines for the Implementation to the California Environmental Quality Act (CEQA). The Class 3 (15303) exemption includes the construction and location of limited numbers of new, small facilities or structures. The Class 4 (15304) exemption includes minor alterations to land including minor grading, trenching and backfill. The Class 6 (15306) and Class 8 (15308) exemption is for information collection and applies to this project since this is pilot program for research, experimental management, and resource evaluation activities which do not result in a serious or major disturbance to an environmental resource. In addition, none of the exceptions for application of a categorical exemption apply to this project.
Attachments
Notice of Exemption
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