Innovative Flow-Augmentation Project to Restore Flows in Redwood Creek

By Salmonid Restoration Federation

This summer Salmonid Restoration Federation (SRF), Stillwater Sciences, and Edwards Excavation will build an innovative flow-augmentation restoration project on the historic Marshall Ranch to improve instream flows in Redwood Creek (a tributary of the South Fork Eel River) for threatened salmon and other aquatic species. This project has been years in the planning and will likely improve Redwood Creek habitat conditions for decades to come.

The design includes two off-channel ponds and more than 100,000 gallons of water storage in tanks to store a total of approximately 10 million gallons of winter water to release incrementally during the five-month dry season when flows in Redwood Creek often become disconnected and impair habitat for Coho salmon, steelhead, and other aquatic species. Despite the legacy impacts of logging and unregulated water diversions, Redwood Creek still retains high habitat value for threatened salmonids.

Since 2013, Salmonid Restoration Federation has been monitoring flows in Redwood Creek and developing flow-enhancement strategies to protect fisheries resources. In conjunction with implementation of the project on the Marshall Ranch, SRF is developing a Storage and Forbearance Program downstream of the Marshall Ranch to ensure that the cool summertime flow releases remain instream and are not diverted by downstream water users. SRF and Stillwater Sciences are currently in the process of conducting site assessments on mainstem Redwood Creek, and are pleased by how many landowners are interested in participating.

Additionally, SRF is pursuing a flow-enhancement project on the Lost Coast Forestland property near the headwaters of Redwood Creek. The Marshall Ranch and Lost Coast Forestland flow-enhancement projects combined would help accomplish our target flow goal of an average of 50 gallons per minute of flow release, which would keep flows connected to allow for fish migration and hydrologic connectivity.

Project Summary

The historic Marshall Ranch, the largest contiguous landowner in the Redwood Creek watershed, is fully protected under a conservation easement. The ranch bridges Redwood Creek, Somerville Creek, and Sproul Creek. This working ranch that has been in the Marshall family ownership since the 1800s is now protected in perpetuity, with restoration opportunities such as a flow-enhancement project that includes 10 million gallons of winter water storage between two off-channel ponds and 100,000 gallons of storage in water tanks that will be plumbed for fire-fighting emergencies. The purpose of this project is to release cool water into Redwood Creek during the five-month dry season to benefit threatened salmonids and other aquatic species. The flow releases will benefit the mainstem of the creek from the Marshall Ranch all the way to the confluence with the South Fork Eel River.

This project was developed by several restoration partners, including Stillwater Sciences, the lead technical consultants; the Marshall Ranch General Manager, David Sanchez, and the Marshall Ranch family representative, Elizabeth Marshall Maybee, who had the vision to preserve the ranch through conservation easements; and Hicks Law, who oversaw the Appropriative Water Right and provides expert legal guidance to the project team. SRF’s Executive Director Dana Stolzman stated, “SRF is the project proponent, but this project could not have evolved without the ongoing support of the Wildlife Conservation Board and the hard work of the project team. In this era of extended drought conditions, climate change, and intensified fire risk, innovative projects like the Marshall Ranch Flow Enhancement are needed to improve instream flows.”

The California Water Action Plan ranks the South Fork Eel as one of the highest-priority watersheds in the state for flow-enhancement projects. Similarly, the Salmon Habitat and Restoration Prioritization Project in the South Fork Eel River recognizes that although Redwood Creek is densely populated and suffers from legacy impacts, it still retains high habitat values for salmon.

After years of outreach, monitoring, and a Redwood Creek feasibility analysis, SRF and Stillwater Sciences have developed a variety of flow-enhancement opportunities ranging from groundwater recharge in the headwaters of Redwood Creek to flow-release projects in the mainstem on the Marshall Ranch, storage and forbearance projects downstream, and a recently funded forest-thinning component that will study the nexus between selective forest thinning and flows.

Recent Project Milestones Include:

In January 2022 the Marshall Ranch Flow-Enhancement Implementation Project was unanimously approved by the Humboldt County Planning Commissioners. Humboldt County Planning Department is the lead agency for CEQA for this exciting project, and it adopted a Mitigated Negative Declaration for the project.

Concurrently, the State Water Board completed a final review of the Marshall Ranch Appropriative Water Right application and approved it in June 2022. This is an exciting milestone because the off-channel ponds will be filled in the winter season for metered cool-water flow releases throughout the five-month dry season.

The Wildlife Conservation Board’s Streamflow Enhancement Program is funding the implementation of the project, which will begin during the summer of 2023. SRF will also receive funding through the North Coast Resource Partnership to identify, design, and implement five water-storage tanks as part of a storage and forbearance program intended to help ensure that the dedicated flows from the Marshall Ranch remain instream and to improve water availability for landowners who may not have sufficient water storage in this under-served region.

Both the flow augmentation and storage and forbearance projects will be operated for a minimum of twenty years as part of Long-term Operations and Maintenance agreements required for Prop 1-funded projects.

SRF and Stillwater Sciences are in the process of permitting the various components of the Marshall Ranch project while working on designs for the Lost Coast Forestland property near the headwaters of Redwood Creek.

SRF and Stillwater Sciences will continue to do pre-project streamflow monitoring and snorkel surveys as well as post-project streamflow monitoring and snorkel surveys once the project is completed.

SRF and Stillwater have conducted tribal consultations with Wailaki tribal members, who are fully in support of both the Marshall Ranch flow-enhancement project and the Lost Coast Forestlands flow-enhancement efforts.

For more information: https://www.calsalmon.org/