SONOMA CREEK AND SEDIMENT: KNOWING WHAT WE DON’T KNOW
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SONOMA SONOMA CREEK AND CREEK AND SEDIMENT: SEDIMENT: KNOWING KNOWING WHAT WE WHAT WE DON’T DON’T KNOWKNOW
MAY 2011
SONOMA SONOMA CREEK AND CREEK AND SEDIMENT: SEDIMENT: KNOWING KNOWING WHAT WE WHAT WE DON’T DON’T KNOWKNOW
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% forest20% grassland & rangeland30% agricultural 15% developed5% 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 drained20% alluvial channels once disconnected now connected
Steelhead Timeline
Sonoma Creek Sediment Sonoma Creek Sediment TMDLTMDL
Main focus: steelhead troutMain focus: steelhead troutState Listing
SECTION 303(d): SEDIMENT
(NUTRIENTS & PATHOGENS)
FundingFUND 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 FactorsWhat factors limit stream health in Sonoma Creek and
tribs?
stage factor impact
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, heat Low to high
Sediment-Related Limiting Factors:
highest during spawning and juvenile rearing
stage factor impact
SpawningFine sediment in spawning gravel
Moderate to high
Spawning/rearing
Decreased channel
complexityModerate to
high
Spawning/rearing
Pool filling by fine sediment Moderate
Rearing/outmigration
Increased suspended
loads stress fishModerate
Sediment Source AnalysisWhat are the major sediment sources and how much do they
input?Sediment Production, Natural
Processes Sonoma Creek Watershed (2005)
52,300 tons/year
Surface Erosion,
6,200 tons/yr, 12%
Channel Erosion and
Incision, 25,400
tons/yr, 49%
Soil Creep, 16,600
tons/yr, 32%
Landslides, 4,100
tons/yr, 8%
Sediment Production, Human Processes Sonoma Creek Watershed (2005)
64,000 tons/year
Channel Erosion and
Incision, 43,300
tons/yr, 68%
Surface Erosion,
8,600 tons/yr, 13%
Landslides, 900 tons/yr,
1%
Roads and Stream
Crossings, 11,200
tons/yr, 18%
+
=Sediment Production, Natural + Human
Processes Sonoma Creek Watershed
116,300 tons/year
45%
55%
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 Sonoma Creek Sediment TMDLTMDL
Main focus: steelhead troutMain focus: steelhead troutState Listing
SECTION 303(d): SEDIMENT
(NUTRIENTS & PATHOGENS)
FundingFUND 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 What are the highest the highest producing producing
sites sites throughout throughout
the the watershed?watershed?