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?