Grant Lake Outlet Valve Replacement Geotechnical Evaluation
Summary
SCH Number
2026080001
Public Agency
Los Angeles Department of Water and Power
Document Title
Grant Lake Outlet Valve Replacement Geotechnical Evaluation
Document Type
NOE - Notice of Exemption
Received
Posted
8/3/2026
Document Description
LADWP proposes to conduct a geotechnical investigation to inform planning and design for the replacement of the malfunctioning Grant Lake outlet valve and for the outlet tunnel gate replacement. Geotechnical borings are necessary to understand the geomorphology of the project area and support project development. LADWP proposes to explore the subsurface materials utilizing sonic drilling methods. Sonic drilling can be used in various soil types, including sands, gravels, and glacial tills, and can also be used to core bedrock. A total of 14 sonic borings are proposed, two of which may be converted into groundwater monitoring wells. The field investigation includes two sonic borings over water in the reservoir using a barge or other watercraft, with the other twelve boreholes along the dam access road and west of the existing shaft and shaft house adjacent to the lake. Drill cuttings will be drummed and disposed of properly offsite. LADWP estimates the borehole drilling process to begin in September 2026 and continue until the end of November 2026.
Contact Information
Name
Marshall Cyr
Agency Name
Los Angeles Department of Water and Power
Job Title
Environmental Specialist
Contact Types
Lead/Public Agency / Project Applicant / Parties Undertaking Project
Phone
Email
Location
Coordinates
Cities
Unincorporated Area; between June Lake and Lee Vining
Counties
Mono
Regions
Northern California, Unincorporated
Cross Streets
Grant Lake Road
Zip
93529
State Highways
CA-158, US-395
Waterways
Grant Lake, Rush Creek, Parker Creek
Township
T01S
Range
R26E
Section
15
Other Location Info
The proposed geotechnical work would occur within and adjacent to Grant Lake.
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Section 15306, Class 6
Reasons for Exemption
In accordance with the California Environmental Quality Act, this project is Categorically Exempt from CEQA review pursuant to Section 15306, Class 6, consists of basic data collection, research, experimental management, and resource evaluation activities that do not result in a serious or major disturbance to an environmental resource. These may be strictly for information gathering purposes, or as part of a study leading to an action which a public agency has not yet approved, adopted, or funded. The proposed project meets the requirements of these exemptions; therefore, no further CEQA review is required.
County Clerk
Mono
Attachments
Notice of Exemption
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