SONOMA CREEK AND SEDIMENT: KNOWING WHAT WE DON’T KNOW MAY 2011

SONOMA CREEK AND SEDIMENT: KNOWING WHAT WE DON’T KNOW MAY 2011 “... somebody's certainly going to... find out what he knows that they may not know, and make sure he knows what they know that he may not know.“ --Donald Rumsfeld

166 square miles 0 to 2,739 feet msl land uses: 30% forest 20% grassland & rangeland 30% agricultural 15% developed 5% wetland beneficial uses: COLD, WARM, REC-1, REC-2, MIGR, RARE, SPWN, WILD Sonoma Valley

Sonoma Creek Watershed 23 to 50 inches annual rainfall 465 miles of USGS blue-line stream Chinook salmon, steelhead trout, California freshwater shrimp Hydromodified: 95% freshwater marsh drained 20% alluvial channels once disconnected now connected

Steelhead Timeline

Sonoma Creek Sediment TMDL Main focus: steelhead trout State Listing SECTION 303(d): SEDIMENT (NUTRIENTS & PATHOGENS) Funding FUND STUDY TO ASSESS POLLUTANT (SEDIMENT) Study 1: Limiting Factors Analysis WHAT FACTORS LIMIT STREAM HEALTH? Study 2: Sediment Source Analysis WHAT ARE THE MAIN SEDIMENT SOURCES? Measures for Action HOW AND WHERE DO WE FOCUS IMPLEMENTATION?

Life Stages and Limiting Factors What factors limit stream health in Sonoma Creek and tribs? stagefactorimpact Upstream migration/ Outmigration 100+ barriers, 25% inaccessible habitat, predation on way out Low to high Spawning and egg incubation Impaired spawning habitat, poor cover, heat Moderate to high Juvenile rearing Poor baseflow, approximately 40% habitat dry, poor cover, heatLow to high

Sediment-Related Limiting Factors: highest during spawning and juvenile rearing stagefactorimpact Spawning Fine sediment in spawning gravel Moderate to high Spawning/rearing Decreased channel complexity Moderate to high Spawning/rearing Pool filling by fine sedimentModerate Rearing/ outmigration Increased suspended loads stress fish Moderate

Sediment Source Analysis What are the major sediment sources and how much do they input? + = naturalhuman

Stream channel contribution 67,700 tons/year 64% human caused

How? (Required) Control upslope sediment discharges --road and stream crossings --surface erosion --shallow landslides and gullies Reduce sediment discharge from channel incision --attentuate, reduce storm peaks --avoid impacts to stream corridors

How? (Recommended) Support habitat enhancement actions --increase channel complexity --enhance summer base flows --address fish barriers Reduce sediment discharge from channel incision --reverse adverse impacts of incision --implement stream restoration projects

Sonoma Creek Sediment TMDL Main focus: steelhead trout State Listing SECTION 303(d): SEDIMENT (NUTRIENTS & PATHOGENS) Funding FUND STUDY TO ASSESS POLLUTANT (SEDIMENT) Limiting Factors Analysis WHAT FACTORS LIMIT STREAM HEALTH? Source Analysis WHAT ARE THE MAIN SEDIMENT SOURCES? Measures for Action HOW AND WHERE DO WE FOCUS IMPLEMENTATION? (leads to Study 3)

Where? Pilot study for site prioritization San Francisco Foundation Bay Fund – 2008 to 2010 Where are the ten highest-producing sites affecting best-value spawning and rearing habitat? Upper watershed, 60 square miles above Eldridge

What are the highest producing sites throughout the watershed?