California Coastal Streamflow Stewardship Project


Across much of California’s north and central coast, lack of streamflow is the single largest factor holding back the recovery of salmon and steelhead. The region’s climate is dominated by a wet season and a dry season, with 90% of the precipitation falling between November and April. Over thousands of years, salmon and steelhead have adapted beautifully to survive in this harsh environment where summer streamflows dwindle to no more than a trickle.

In recent times, however, water diversions for farms and residences have tipped the delicate hydrologic balance. To make matters worse, these demands are greatest in the summer and fall, when streamflow is lowest.  Many key tributaries now go dry every year, leaving both fish and people scrambling to find water.

The goal of TU’s coastal streamflow stewardship work is to improve dry season streamflows for the benefit of native coho and steelhead populations.  Our work is based on two simple principles:

  • There is ample water for both humans and fish -- the problem is timing.
  • The same projects will help both fish and people.


Our basic approach is to build projects that reduce peoples’ dependence on unreliable dry-season streamflows, allowing them to leave more water in streams when fish need it most. Here are some examples:

Storage tanks.  Storage tanks provide homeowners and small businesses with a secure source of water to replace stream diversions during the dry season. A 40,000-gallon storage system can divert and store enough water during the wet season to meet the needs of a typical residence for 3-4 months at the height of the dry season. In coastal streams, the water left instream can make the difference between life and death for juvenile salmon and steelhead.

Ponds.  Ponds of several acre-feet can provide small farms and vineyards with enough irrigation water to last the dry season. Where space is an issue, smaller ponds can allow landowners to reduce diversion rates and reduce impacts of sudden diversions for frost protection. 

Frost fans.  In some cases, diversions for frost protection can be replaced entirely with fans that prevent frost by circulating air.

Conjunctive use of groundwater.  Some farms can reduce streamflow impacts by seasonally switching to groundwater instead of stream diversion. Such projects are not appropriate everywhere and must be carefully designed.

Rainwater catchment.  Roofs can be used to collect rainwater that can be stored and used in place of dry season diversion. Large roofs on barns or other agricultural outbuildings are ideal. Where annual rainfall averages 20 inches, a 2000-square foot roof can capture about 20,000 gallons of water per year.

Most of our projects involve a simple quid pro quo arrangement where TU helps landowners obtain grant funds to construct secure water supplies, and in return they agree not to divert water during the dry season for the life of the project. This creates a classic "win-win."

We also have produced two informational brochures with our partners in the Russian River Coho Partnership and the California Coastal Coho and Steelhead Coalition.


Coho Partnership (final brochure).pdf


Whitethorn School:  TU partnered with Sanctuary Forest and the Southern Humboldt Unified School District to build an 80,000-gallon storage system that allows the Whitethorn School to forego diversion from the Mattole River for several months each summer and fall. This leaves more water in the river reach containing the most important rearing habitat for native coho salmon and steelhead.

Fans for Fish: Martorana Family Winery has demonstrated its commitment to land and water stewardship and its enthusiasm for protecting and restoring high-quality habitat for salmon. Located in the Dry Creek Valley in Sonoma County, the Martorana Family practices organic farming and has undertaken a whole suite of restoration projects. Most recently, the vineyard made a dramatic change in its water management for frost protection by installing a frost fan. The project serves as a model for sustainable water use and will benefit endangered coho salmon and threatened steelhead trout in the Russian River watershed.

Steelhead Vineyards: TU partnered with Quivira Vineyards and Winery. The result? Improved habitat for salmon and steelhead and a unique partnership with Steelhead Vineyards. Proceeds from Steelhead Vineyards fund TU’s work and restoration projects.

Staff Contact

Mary Ann King
Stewardship Manager

Matt Clifford
Staff Attorney

Author of this Page

Sam Davidson
California Communications Director

California Coast; Russian River; Pajaro River; Mattole River; Pescadero Creek


Steelhead Trout

Coho Salmon

Coho Salmon

Risks to Fishing 

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