In Spite of Rainy Year, Redwood Creek Stopped Flowing in Multiple Spots During 2017; The Salmonid Restoration Federation Is Developing Plans to Help
Even after the abundant rainfall of the 2016/17 rain year, Redwood Creek stopped flowing in six out of nine places it was monitored by the Salmonid Restoration Federation (SRF). The SRF recently concluded its fifth year monitoring low flows Redwood Creek, the 26-square mile watershed that borders the Mattole watershed and flows into the South Fork Eel River.
Redwood Creek flows east from its neighbor the North Fork of the Mattole near Whitethorn Junction and empties into the South Fork of the Eel near Redway Beach. The Briceland Thorn Road roughly parallels Redwood Creek from Huckleberry Hill east to lower Redway. The major tributaries of Redwood Creek include Dinner Creek, China Creek, Miller Creek, Summerville Creek, and Seely Creek.
What Should Be:
Given the high average annual precipitation and large drainage area, Redwood Creek should be a critical tributary for juvenile salmonids in the South Fork Eel watershed. Historically, Redwood Creek supported coho, Chinook and steelhead providing important cold-water refugia for juvenile salmonids.
The Sad Reality:
SRF began a five-year study of low flows in Redwood Creek in 2013 to better understand the flow patterns and prioritize water conservation efforts in the impaired watershed which houses hundreds of residents using Redwood Creek and its springs and headwaters for their domestic water source.
In 2017, SRF’s Monitoring Coordinator, Bill Eastwood, began monitoring Redwood Creek’s summer flows on June 23. Flows decreased steadily throughout the season. 2016 and the four preceding years had been extremely dry while precipitation in 2017 had a higher than average total.
As expected, flows were markedly higher earlier in 2017 compared to 2016. For example, in mid-June 2016, the average flow was 583 gallons per minute (GPM) while in mid-June 2017, the average flow was nearly double at 1,137 GPM.
During July, most flows remained higher than the 2016 average (Dinner Creek was an exception). But sadly, Miller Creek stopped flowing in mid-August in 2017, as did some upper mainstem Redwood Creek tributaries by mid-September.
The SRF monitoring team measured a steady decline in flows for all nine monitoring sites in August and September. By the end of October, Redwood Creek was separated into isolated pools and out of nine monitoring sites, only three maintained flows over one gallon per minute.
Comparing data between monitoring sites, Dana Stolzman, Executive Director of SRF, said the data revealed a drastic flow reduction in reaches, or stretches of stream, that were populated compared to reaches that had no residents or withdrawals.
And the monitoring data showed what Stolzman called “pumping signatures” which are sudden, temporary drops in flow that generally recur. The assumption is these signatures or drops are caused by an in-stream pump or a near-stream well being used in the low-flow season.
Planning for Flow Restoration:
For more detailed information, SRF created a Redwood Creek low-flow monitoring page to share flow data, project resources, and an interactive graph. Stolzman explained, “Seeing the flow trends through the years underscores how much Redwood Creek would benefit from a coordinated, community-led water conservation program.”
Stolzman explained SRF has used the low flow monitoring to better understand the flow thresholds and to gain understanding of the flow releases required to mitigate the withdrawals. During the process, SRF has developed conceptual proposals for rainwater catchment ponds and groundwater recharge projects. In the feasibility study on their webpage, SRF writes of one such concept. This consists of
a 50-million-gallon flow enhancement project adjacent to the right bank of Redwood Creek near Briceland and a 300,000 gallon demonstration rainwater catchment pond at Beginnings Inc. in Briceland. …. The physical characteristics of the site combined with enthusiastic landowner support for the project offer excellent potential. …The 300,000 gallon demonstration rainwater catchment pond proposed for Beginnings would provide … flow enhancement benefits while also providing a demonstration project for the community.
Groundwater Recharge Has Great Potential:
Stolzman noted, “It has been interesting to compare the low flows from the extended drought years to this year where we had high precipitation. Despite high rains late into the season, flows in the some of the tributaries of Redwood Creek including Miller Creek fell to less than a gallon per minute by August.”
Stolzman added the estimated human water usage is about 12 million gallons in this watershed and “[p]rojects like the 50-million gallon enhancement could greatly improve streamflows and provide cool water for juvenile salmonids during the dry season when flows and water temperature are most critical for this life stage.”
Groundwater recharge not only improves flows but also, cools the water in the stream. Stolzman said SRF should know by next month whether it will be awarded a planning grant to help fund taking the plans from concept to fully designed and permitted projects ready to implement.The five-year low-flow study funded in part by money from NCRWQCB as well as Fish and Wildlife, has informed their concepts and given SRF and its partners time to build relationships with landowners.