Old Santa Cruz Highway Culvert Repair
Summary
SCH Number
2026010765
Public Agency
California Regional Water Quality Control Board, San Francisco Bay Region 2
(RWQCB)
Document Title
Old Santa Cruz Highway Culvert Repair
Document Type
NOE - Notice of Exemption
Received
Posted
1/23/2026
Document Description
The Project is located about 0.2 miles east of Highway 17 and south of Lexington Reservoir in Los Gatos, Santa Clara County (Lat. 37.170359; Long. -121.986208). The Project is along a steep hillside and crosses Arroyo Mocho Creek (Creek), which is an ephemeral creek and a headwater tributary of Lexington Reservoir (Reservoir) along Los Gatos Creek that originates upstream from the Project area in the Santa Cruz Mountains. The Creek is in the Guadalupe River watershed and eventually flows into San Francisco Bay.
The Project purpose is to repair an exposed culvert outlet downstream of the Highway that failed in a landslide and triggered bank erosion due to heavy and long-duration storm events during the 2022/2023 Winter season. The Project will stabilize the active roadway crossing at the Creek to protect public safety and restore drainage flows between the Project reach and the Reservoir. The culvert outfall will be extended down the hillside to a less steep gradient and armored with rock riprap for energy dissipation. The extended culvert will dewater the portion of the Creek between the original culvert outlet and the new downstream outlet.
The Project will involve landslide and roadway repair that consists of installation of a soil nail and micro pile-supported shotcrete wall to restore the road width and a four-foot shoulder, which will be necessary for a guardrail above the wall. Controlled Low Strength Material (CLSM) backfill will be poured between the slide face, temporary plug and the back of the shotcrete wall. The shallow landslide material below the toe of wall will be stabilized to protect the bottom of the wall from undermining. A pinned mesh apron and horizontal drains will likely be needed to capture the seepage below the wall. The culvert outfall and downstream flow will require additional armoring for scour protection.
Contact Information
Name
Nathaniel Goetz
Agency Name
California Regional Water Quality Control Board, San Francisco Bay Region 2
Job Title
Water Resource Control Engineer
Contact Types
Lead/Public Agency
Address
Phone
Location
Coordinates
Cities
Los Gatos
Counties
Santa Clara
Regions
San Francisco Bay Area
State Highways
0.2 miles east of Highway 17
Waterways
Arroyo Mocho Creek, which is an ephemeral headwater tributary of Lexington Reservoir
Notice of Exemption
Exempt Status
Categorical Exemption
Type, Section or Code
Class 2, Section 15302 - replacement or reconstruction of existing structures and facilities
Reasons for Exemption
The Project involves a small amount of permanent impacts to waters of the State (<0.01 acres) to protect critical infrastructure, maintain safe and adequate stormwater runoff and prevent further erosion in the Creek channel. The Project will provide compensatory mitigation for the temporary and permanent impacts to waters of the State. The Project’s temporary impacts will be mitigated by hydroseeding with native plant species at temporarily disturbed areas along 62 LF of the Project reach. On-site mitigation for permanent impacts from new solid fill associated with the new culvert extension and apron will involve removing debris within the Creek channel at a 2:1 ratio. A total of 124 LF (628 SF) of the on-site Creek bed and bank will be enhanced.