Ralston Afterbay Sediment Removal and Trash Rack Installation Project
Summary
SCH Number
2025081018
Public Agency
Placer County Water Agency
Document Title
Ralston Afterbay Sediment Removal and Trash Rack Installation Project
Document Type
NOE - Notice of Exemption
Received
Posted
8/22/2025
Document Description
In 2022, the Mosquito fire burned nearly all the surrounding forest around Ralston Afterbay, resulting in accumulation of sediment in front of the Ralston Afterbay Dam, as well as the Ralston-Oxbow Tunnel Intake. This sediment affects the safe operation of the Ralston Afterbay Dam low level outlet (LLO), and operation of Oxbow
Powerhouse, which requires water delivery from the Ralston-Oxbow Tunnel Intake. The project includes physical removal (mechanical dredging) of approximately 40,000 cubic yards of accumulated sediment from Ralston Afterbay in the vicinity of the Ralston Afterbay Dam's Low Level Outlet and the Ralston-Oxbow Tunnel Intake structure. A crane would place 3-5 barges into the Ralston Afterbay and an excavator would be loaded onto one of the barges. Sediment would be placed on remaining barges to allow water to drain off. Removed sediment will be trucked off site to an approved receiving area (EBRL Sediment Disposal Area approximately IO miles away). Once sediment is removed, the existing steel trash rack will be replaced with a new structural trash rack on the Ralston Afterbay Dam LLO to allow required operation/cycling of the LLO, even with future sedimentation.
Contact Information
Name
Heather Trejo
Agency Name
Placer County Water Agency
Job Title
Environmental Scientist
Contact Types
Lead/Public Agency
Address
Phone
Email
Location
Counties
Placer
Regions
Unincorporated
Cross Streets
Forest Road 23, located on U.S. Forest Service lands within the Tahoe National Forest
Total Acres
2.4
Waterways
Ralston Afterbay
Township
13N
Range
11E
Section
3
Base
MDM
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Class 1 (b), Section 15301, Class 4 (c)(g), Section 15304
Reasons for Exemption
The project consists of the repair, maintenance or minor alteration of existing public structures, facilities, or mechanical equipment, involving negligible or no expansion of capacity. (Guidelines Article 19, Section 15301 (b)). The project consists of minor public alterations in the condition of land and/or vegetation. (Guidelines Article 19, Section 15304 (c) (g).
County Clerk
Placer
Attachments
Notice of Exemption
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