Draft Tenmile Creek Watershed Conservation and Restoration Action Plan Released to Public

This is a press release from the Eel River Recovery Project:

The Eel River Recovery Project released the public draft of the Tenmile Creek Watershed Conservation and Restoration Action Plan, which is the culminating product of a two year pilot project.  The document is available at www.eelriverrecovery.org. and the public is invited to comment.

The California State Coastal Conservancy (SCC) awarded ERRP Prop 1 funds to work on water conservation, riparian restoration and erosion control.  The Action Plan reports on Tenmile Creek riparian conditions and restoration opportunities, erosion sources and proposed fixes for some, and community water conservation initiatives that would allow native fish to flourish and provide water security for domestic and agricultural water users.

Dennis Hogan at future site of bank restoration project on Cahto Creek. 6/26/19.

Tenmile Creek riparian zones are characterized as high quality, with old growth oaks comprising part of the canopy on the valley floor and recovering riparian zones on tributaries coming off Cahto Peak.  The report identifies 14 sites of major bank erosion.  ERRP recently won a grant to fix 620 feet on Cahto, Mill and Streeter creeks in 2021.  Additional grants will be sought for identified sites with landowner interest, and ERRP will continue to pursue additional partners in restoration where there are problems with bank erosion.  Reducing sediment from these sources can improve salmon and steelhead spawning habitat.

The Action Plan explains how gully erosion can alter watershed hydrology, reduce summer baseflows and also create sediment pollution problems.  ERRP has applied for an additional SCC Prop 1 grant to plan and permit structures to control gullies and other erosional features in lower Tenmile Creek and Cahto Creek.  There is a geologic fault  running down the middle of the Tenmile Creek watershed from north to south that divides the Coast Range from the Central Belt Mélange Terrain, which gives rise to grasslands in the eastern part of the watershed.  These areas are particularly susceptible to gully erosion if roads are constructed and downspouts from road drainage are not properly armored.

Water supply in tributaries of Streeter and Big Rock creeks, both pilot project sub-basins of interest, was compared to the control stream Elder Creek using modeling.  Flow impairment in Streeter and Big Rock creeks appears to be driven by increased evapotranspiration of the second growth forest, as well as Douglas fir trees over-topping oaks.  Since oaks use less water than fir, this unwanted succession also decreases baseflows.  ERRP is obtaining a forest health grant to begin work on this problem in cooperation with the Tenmile Creek Watershed Council, which has plans to focus on forest health and to bring in resources for implementation.

ERRP discovered that there was a need to assist with obtaining water security for a large organic farm at Black Oak Ranch and at Camp Winnarainbow, which hosts economically disadvantaged inner-city youth to learn about art and nature each year.  ERRP has included planning and permitting for needed water storage for the farm and camp in a recent SCC Prop 1 phase two application, and a subsequent grant will be sought for implementation.  The ultimate goal is to make it so both enterprises can forbear from summer water use of Streeter Creek in exchange for infrastructure that provides for their water needs and future water security.

The Action Plan defines a priority water conservation area in the western part of the Tenmile Creek basin, where partnerships with landowners who want additional water storage to enable forbearance will be sought.  The report discusses groundwater issues, including the connection between surface water and groundwater, and points out potential conflicts that could arise in the future.

The fish community of Tenmile Creek is described in detail, with colorful photos of fish taken during the two year pilot project.  The portrait of Tenmile Creek health that emerges from the report indicates signs of resilience, but also ecological stress.  Water temperatures can be acutely warm for salmon and steelhead, especially in dry years.  Reaches of main Tenmile Creek and many of its tributaries also become disconnected in dry years, whereas they were all formerly perennial.  Hardy warmwater adapted native suckers are becoming rare.  As the main branches of Tenmile Creek dry up in summer, water quality in isolated pools deteriorates, and non-native species proliferate.

Yearling steelhead trout in Big Rock Creek. 6/2/20.

Sufficient flows in the summer of 2019 allowed high survival of juvenile steelhead and early reconnaissance in 2020 indicates a good level of spawning.  Basinwide, Eel River Chinook salmon are trending downward, but they sometimes spawn in the thousands in Tenmile Creek in years of high abundance like 2010-2012 and 2016-2017.  Coho salmon are rare, but achieving our goal to restore perennial cold water habitat may help them to recolonize.

ERRP will be accepting comments on the Action Plan for 30 days up until Wednesday, July 22, 2020.  There will be a public presentation before July 31, if not prohibited by restrictions related to the pandemic.  An announcement will be made. You may also call 707-223-7200 to find out more.  Copies of the Action Plan are available on-line at www.eelriverrecovery.org. and will be made available in hard copy at the Laytonville County Water District office.  Call 707 223-7200 to request a copy.