SPAWN staff and volunteers visit the Redi-Mix project area following construction.
After 2 months of construction, SPAWN’s Sediment Load Reduction Project in the Lagunitas Creek Watershed has concluded! However, there’s still more to be done…here’s the latest update on the final project area and the volunteer opportunities to come this winter.
The Lagunitas creek watershed is home to endangered and threatened species, being the southernmost extent for endangered California Coast Coho (CCC) salmon migration, with returning populations that are 90% down from historic levels. This project was aimed to address one of the main sources of pollution that impacts water quality within the Lagunitas Creek Watershed, fine sediment. Fine sediment sources can come from failing slopes where erosion is occurring instream, or in our case, from impaired dirt roads connected to the stream way. Runoff from dirt roads, if not properly diverted, can end up in stream crossings or smaller drainages that flow into Lagunitas creek, contributing to water quality impairments. Working on Golden Gate National Recreation Area Land, 1 mile of priority sections of dirt road on McIssac and Zanardi Ranches were repaired, upgraded, and improved.
Sediment load reduction was also focused at the abandoned Redi-Mix concrete plant on Black Mountain Ranch; a private ranch, in the Agricultural Production Zone, under a rolling 20-year Williams Act contract, and a MALT Easement. SPAWN conducted Phase 1 of floodplain restoration in 2016 with the completion of Phase 2 this year, in 2024. This concrete plant was in operation from 1958 to 2012. Concrete stalls, staging platforms, parking areas, and leftover cement fill were finally removed, resulting in about 500 cubic yards of cement taken away and recycled. With approximately 0.6 acres of the cement plant staging area removed, close to an acre of land can be restored, expanding the floodplain riparian corridor along 350 linear feet of Lagunitas Creek. This site can flood during heavy rain years. Rather than having road runoff and water spread across impervious surfaces and enter back into Lagunitas creek as it has done for the last 60 years, water can now supply a native landscape, recharge, filter through the soil, and benefit riparian habitat.
SPAWN is preparing for the revegetation stage throughout the winter season, where volunteers can be involved in restoration. Native grass seed blends from Larner Seeds in Bolinas, CA, were selected, mixed, and tilled into new topsoil across the different areas of the Redi-Mix site. The largest area will become a native grass meadow with trees and shrubs planted along the edge, creating a seamless transition from the existing mature forest to the newly restored area, and leaving some space on the floodplain open so that plantings will support a mixed-land use. Black Mountain Ranch will utilize some space on the periphery of the floodplain to grow lavender and other plants for commercial purposes.
California native wildflowers will grow throughout the area to support pollinators. Eight trees and twenty-two shrubs will be planted along the riparian buffer zone, along with hundreds of perennials and vines and hundreds of grass plugs will be planted by the end of this winter. Help reach our goal and join SPAWN at their upcoming Volunteer Habitat Restoration Events. All events can be found on SPAWN’s event calendar https://seaturtles.org/events/.
Any questions about SPAWN’s Sediment Load Reduction Project in the Lagunitas creek watershed, contact SPAWN’s Conservation Project Manager, Ayan Hayes, ahayes@tirn.net. Funding for this project has been provided in full by the United States Environmental Protection Agency under the Federal Nonpoint Source Pollution Control Program (Clean Water Act Section 319) through an agreement with the State Water Resources Control Board. Pacific Watershed Associates designed the project while Bohan & Canelis General Engineering implemented the design.
Before photo of the upper area at the Redi-Mix site during construction as concrete was being removed.
After photo of the upper area, following concrete removal and the distribution of fresh top soil.
