Partnering for Streamflow Resilience in Mill Creek

Low stream flows in Mill Creek watershed continue to impact the population of our native Coho salmon and steelhead trout, which depend on this unique habitat during key stages of their life cycle. To address this, our Water Resource Team has been collaborating with landowners, community members, Trout Unlimited, and Coast Range Watershed Institute to research and develop a range of tools to enhance streamflow throughout the year – helping ensure these salmonids have the water they need to grow, thrive, and return to these headwaters after their adult life in the Pacific.

One promising strategy is the use of rainwater catchment systems, which allow landowners to collect rain during the rainy season and store it for use in the dry season, which offsets the use of other water sources which draw on the creek and helps keep water flowing in the channel. We’ve successfully installed over 350,000 gallons of rainwater storage to help improve streamflow in Mill Creek and Mark West Creek watersheds.

In March 2023, we received a grant from the California Department of Fish and Wildlife (CDFW) through the “Cutting the Green Tape” initiative to connect with landowners and explore additional tools to improve streamflow such as directly releasing water from a reservoir into the creek during critically dry periods. Since then, we outreached to over 70 local landowners – 15 of whom expressed interest in participating in some type of streamflow enhancement project. Our Water Resources Team met with each of these 15 property owners one-on-one to explore what projects might be a good fit. Some properties were identified as well-suited for an existing rainwater catchment program and have either had rainwater tanks installed or are in the process of doing so. Of the remaining properties, six were developed into “final” project concepts, with extensive research conducted to determine what would be needed to create or improve existing reservoirs.

These span the upper, middle, and lower parts of the watershed, each tailored to site-specific needs—whether it’s improving summer rearing habitat, increasing flow connection to Dry Creek, or supporting fire protection during the dry season. With the help of monitoring tools like streamflow cameras, we aim to time water releases for maximum ecological benefit.

Water Resources Project Manager Colin Nicol, shared that, “Storage and forbearance projects (rainwater capture) and environmental flow release projects (releasing water from a reservoir) were identified as priority strategies to improve salmon survival approximately a decade ago. It is an exciting time to see landowners and agencies partnering to implement projects at a scale that will start making a meaningful impact in these watersheds.”

Next up: We’ll be presenting these projects to CDFW and applying for additional funding to support design and implementation. We’re excited about the momentum and grateful to the landowners and partners helping make this possible.