Neefus Gulch Coho Salmon Barrier Removal Project Design at Appian Way

Location of Project:

39.17875000 : -123.57107000 – Earthen Barrier Forming Pond 
39.17592000 : -123.56846000 – Appian Way Culvert Barrier

​​COMPLETED: This project developed engineered designs for a wood loading project on Neefus Gulch, a salmon-bearing tributary to the North Fork Navarro River in Mendocino County, CA. The planned wood-loading work on Neefus Gulch is tied to an ongoing fish passage work in the watershed to address two complete (filter=RED) barriers. During the initial data collection and topographic survey work at the most downstream crossing site at Appian Way, the project team identified a design concern associated with the stream conditions on the downstream landowner’s property (Mendocino Redwood Company). This project developed designs for large wood features that will address channel incision, trap sediment, raise the channel bed in the project reach, and stabilize downstream knickpoints to reduce sediment downstream sediment delivery and ensure structural integrity upstream of the Appian Way crossing.

Forum Funding Received: $39,513

Description of Project, including deliverables and outcomes: Develop engineered designs to address fish passage at the Appian Way crossing on Neefus Gulch (tributary to the North Fork Navarro River) within the Rancho Navarro Subdivision. The site on Appian Way is an undersized, ill-aligned culvert that is a total barrier. 

This project restores fish passage in Neefus Gulch at a known fish passage barrier on Appian Way by developing final designs that will lead to implementation of a culvert replacement project that uses instream large wood as grade control downstream. 

About 700 feet downstream of the road-stream crossing, there is a 5.3-foot high knickpoint with two steps that drop into a highly incised channel. The drops in this feature are comprised primarily of clayey-sand ledges and a rootwad that has rolled into the channel from the adjacent eroding bank (refer to Fig. 4 in Appian Way Design Memo). This knickpoint appears to be progressing slowly upstream as it erodes through the clayey sand, as evidenced by the u-shaped, highly entrenched channel downstream of the knickpoint. The rootwad has been holding grade for several years, but is not considered to provide long-term stability. 

The project area at Neefus Gulch is the property of the Mendocino Redwood Company, and consists of an about 1,400-foot long incised channel reach upstream of the bridge on Masonite Road. This reach continues to actively incise and widen through bank failures, mobilizing excessive amounts of sediment into the stream and contributing to headcut migration within the channel. Several knickpoints within the project area are arrested by Redwood woody debris, and  some locations are presumed to be partial fish passage barriers.  Potential failure at the Redwood knickpoints, and resulting channel incision, present challenges to the integrity of the upstream crossing currently under design on Appian Way. To address those challenges the Project Engineers have recommended performing a topographic survey in the proposed project area and preparing design plans to accompany the design work at Appian way that is already ongoing with the Rancho Navarro community. 

The intent of the proposed wood-loading in the incised reach is to construct large-wood features that trap sediment, raise the bed of the channel, and stabilize the downstream knickpoints, thus reducing sediment delivery to the downstream and ensuring structural integrity upstream at the Appian Way Crossing. This project will result in the replacement a known barrier (culvert crossing),thus improving fish passage for Coho Salmon and steelhead rout and better routing flows and sediment directly to the North Fork Navarro River. This work is integral to the overall design approach and long term success of the restoration currently under design at Appian Way. 

Time frame: 
The survey and design plan preparation will be performed assuming that implementation will occur in the summer of 2019.  

    • Winter/Spring 2018: Topographic surveys
    • Summer 2018: Design plan preparation
    • Fall 2018- Winter 2019 (or as funding opportunities arise): Secure Implementation Funding & Permitting approvals (lead by TU)
    • Implementation: Summer 2019 (pending implementation funding award) 


    • Draft design plans in 11×17 pdf format
    • Final design plans in 11×17 pdf format signed and stamped by a licensed California Civil Engineer

​The current limit of anadromy in Neefus Gulch is defined by the Appian Way culvert crossing, which consists of two culverts. The first culvert is a 5′ high x 5.3′ wide x 34′ long metal pipe with a 2% slope. There is a 3′ high plunge at the outlet; the maximum depth within 5′ of the outlet is 3.7′. The bottom of the culvert is lined with asphalt. The second culvert is parallel to the first. It is a 3.2′ high x 2.7′ wide x 40′ long corrugated metal pipe. The plunge at the outlet is 5′ high. There is no rust line. Both culverts are barriers to juvenile and adult salmonids at all times (CDFW, 2011; K.Vodopals, 2011). According to a 2011 CDFW survey completed by A. Renger and T. Fuller, there is approximately 7,726 feet (1.46 mi) of potential habitat upstream of the downstream most barrier (Appian Way culverts).

This project has been funded by CDFW and the State Coastal Conservancy and is endorsed by the local Resource Conservation District as a high priority project.

The California Fish Passage Forum has nine overall objectives. This project will help to address: 

    • 1. Remediate barriers to effective fish migration.
    • 9. Implement education and outreach activities, targeting both the general public and fish passage practitioners.

​The project has been and will continue to be highlighted in outreach activities presented by TU and its partners. For example, the Neefus Gulch design project was featured at the SRF Fish Passage Design Workshop in March 2017. 

Anadromous fish species that will benefit from the project: 

    • Coho salmon
    • Steelhead/rainbow trout

The miles of stream opened as a result of implementing the project: 1.46

Access to Forum’s priority habitats that will be made available as a result of the project: 

    • Spawning habitat
    • Rearing habitat

National Conservation Strategies that will be addressed by the project: 

    • 1. Protect intact and healthy waters.
    • 2. Restore hydrologic conditions for fish.
    • 3. Reconnect fragmented fish habitats.
    • 4. Restore water quality.

USFWS Climate Change Strategies that will be addressed by the project: 

    • 3.1 Take conservation action for climate-vulnerable species.
    • 3.2 Promote habitat connectivity and integrity.
    • 3.5 Conserve coastal and marine resources.
    • 3.6 Manage genetic resources.

How the project addresses climate change: The proposed project will design and eventually implement proactive conservation measures Coho Salmon and Steelhead Trout which are both listed under CA state and Federal ESA. The project intends to improve instream habitat conditions, restore fish passage, and address sedimentation . The project will connect fragmented habitats within Neefus Gulch which is a coastal anadromous tributary to the North Fork Navarro River, a core recovery watershed for endangered CCC Coho Salmon.  According to recent genetic data collected by NMFS Biologist Carlos Garza, the coastal populations of salmonids within Mendocino County watersheds are very important populations to conserve within the CCC Coho Salmon DPS due to the genetic diversity that exists in the region.​