Fall Creek Fish Ladder Improvement Project

Construction in the streambed has been completed, surface infrastructure to be completed in January 2024. 

Since 2008, the District has owned and operated the water diversion and fish ladder structure on Fall Creek, approximately 0.4 miles upstream of the confluence with the San Lorenzo River in the town of Felton. Constructed approximately 30 years ago, the fish ladder was designed with jump heights that have since been identified as excessively high for salmonid passage. In 1995, major modifications were made to the fish ladder. Foundation elements associated with those modifications were not keyed into the streambed, resulting in sub-surface seepage below and around the existing weirs and slabs and making the fish ladder difficult to operate and maintain.

In the fall of 2013, the Fall Creek Fish Ladder underwent an initial repair to address some of these issues such as sealing subsurface seepage and removing accumulated sediment to reduce turbulence within ladder chambers, ensure sufficient flow over weir structures, and reduce jump height at the weirs. However, jump heights could not be fully reduced to current standards without major changes to the existing structure. As such, the average drop height at the ladder weirs is approximately 18 inches, whereas current CDFW and NOAA fish passage design standards recommend jump heights of 12 inches for adult steelhead and 6 inches for juveniles (NMFS 2007).

The purpose of the current project is to modify the fish ladder and screened intake structure to meet current CDFW and NOAA fish passage design standards, while simultaneously addressing structural deficiencies and improving access for maintenance and operation of the facility. The District has developed the improved fish ladder design over several years in consultation with NMFS and CDFW. During this process, NMFS approved a juvenile passage design variance from 6-inch to 12-inch vertical drops and noted CDFW’s concurrence with this variance (NMFS 2021). The project designs have been fully approved by the agencies.

Fall Creek Fish Ladder Project and Conceptual Model: The proposed fish ladder improvements include six new or modified concrete weirs downstream of the intake screen with 12-inch drop heights between each. A seventh concrete weir will be installed upstream of the intake screens to provide grade control, and will be set to 6 inches. The upstream grade control weir is designed to concentrate flow toward the center of the channel and promote plunging flow into the pool. This will help to maintain sediment transport through the pool and a scoured zone along the intake screens (Waterways 2021). The two new weir pools will replace riffle and shallow pool habitat with up to 4-foot deep ladder pools that facilitate better leaping conditions and fish passage success through the ladder. Finally, the larger and deeper weir pools within the new ladder will provide access and availability to limited pool habitat for juvenile steelhead rearing (NMFS 2021). Lampreys also use the fish ladder and call the river home. The fish ladder also serves as an intake point where the San Lorenzo Valley Water District collects surface water, which is treated at the nearby Kirby Water Treatment Plant. 

On October 2022 the District was awarded a $1,116,166.00 grant towards construction of the project through California Department of Fish and Wildlife's Proposition 1 Watershed Restoration Grant Program

• Cost: $2,365,720
• Funding Source: Loan and CDFW Grant
• Start Date: June 2023
• Estimated Completion: January 2024 (Streambed activities completed in October 2023)
• Location: Felton
• Key elements:
  • Improved, expanded fish ladder
  • Meets current environmental standards

Description: The Fall Creek Fish Ladder Improvement Project in Felton builds or modifies six concrete structures downstream of the existing intake screen. These structures, called weirs, are separated by a 12-inch step. A seventh weir will be installed upstream of the intake screens, which will be set to a 6-inch step. This upstream weir helps control and direct water.

Awarded Contractor: Syblon Reid Construction

• Bidding documents & information 
• Syblon Reid Construction Proposal
• Design document (100%) 
• Construction baseline schedule (subject to change)

Questions? Please contact the District Engineer 831-338-2153 or email FallCreek@slvwd.com