April 4, 2008

Variation in salmonid bed-habitat conditions with sediment yields in

Lagunitas and San Geronimo Creeks

Marin County, CaliforniaBarry Hecht, David Shaw, Jonathan Owens, Mark Woyshner

Balance Hydrologics, Inc.800 Bancroft Way, Suite 101, Berkeley, California, 94710

PO Box 1077, Truckee, California, 94160(510) 704-1000

dshaw@balancehydro.com

and

Eric Austensen Streamline Engineering

2727 Marra RoadOccidental, California, 95465

Overview

Study area and backgroundHydrology during the monitoring

periodThe ThesisThe ApproachFindings

Location

Bed monitoring sites

Location

Balance Hydrologics K4 – San Geronimo Creek Stream Gage

USGS 11460400 and Balance Hydrologics KC

– Lagunitas Creek at

Samual P. Taylor State Park Stream Gage

KB – Below Shafter Bridge

KH – Kelley’s Upper State

Park

Bed monitoring sites

Watershed HydrologyPeak Discharge, 1980 to 2007

Watershed Hydrology

Main Monitoring Program ElementsStudies began in 1979 as a condition of the EIR on raising Peters Dam to increase

storage in Kent Lake

Geomorphic reconnaissance and bed conditions (Balance Hydrologics; Streamline, 1979-present)

Stream and sediment gaging(Balance Hydrologics, 1979-present)

Fisheries investigations and monitoring(various consultants; MMWD; RWQCB staff, 1976-present)

Scour chain studies in spawning areas (Balance Hydrologics, 2002-2006)

The Gestalt

Bed condition surveys and sediment transport data provide information about immediate and long-term changes in watershed and bed habitat conditions.

Relating the two means that bed sedimentation – or improvements in bed conditions – can be monitored more effectively and frequently.

MethodologyBed Census

1. Establish reach morphology(Geomorphic

reconnaissance)

MethodologyBed Census

1. Establish reach morphology

Segment

MethodologyBed Census

1. Establish reach morphology

Segment

Sequence

MethodologyBed Census

1. Establish reach morphology

Sequence

Site

Segment

MethodologyBed Census

1. Establish reach morphology

2. Modified Wolman Pebble count

3. Visual estimate of embeddedness

4. Bed core

MethodologyBed Census

1. Establish reach morphology

2. Modified Wolman Pebble count

3. Visual estimate of embeddedness

4. Bed core5. Annual cross-section

surveys

MethodologySediment Transport

Instantaneous bedload sediment measurements

Instantaneous suspended sediment measurements

Continuous streamflow gaging

2002-2003 pulse and hydrologic context

2002-2003 pulse and hydrologic context

2002-2003 pulse: sediment transport rates

The Gestalt

How is the 2002 sediment pulse reflected by changes in bed conditions?

2002-2003 pulse: mean bed elevation

KB – Below Shafter - Pool

Increase in sand, cobble, organics

2002-2003 pulse: bed cover

KH – Kelley’s Upper - Pool

Increase in sandDecrease in cobbles, bedrock

2002-2003 pulse: embeddedness

KH – Kelly’s Upper - Pool

Slight increase in embeddedness, followed by mild recovery

2002-2003 pulse: mean bed elevation

KH – Kelley’s Upper State Park

Slowed rate of incision

Conclusion Bedload delivery rates and changes in bed conditions are closely

related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek during a series of years with only moderate flows

Conclusion Bedload delivery rates and changes in bed conditions are closely

related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek

The most direct response was measured as changes in the percent of bed area covered with fines (<4 mm) and cobbles.

Conclusion Bedload delivery rates and changes in bed conditions are closely

related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek

The most direct response was measured as changes in the percent of bed area covered with fines (<4 mm) and cobbles.

Embeddedness is less responsive to changes in sediment transport.

Conclusion Bedload delivery rates and changes in bed conditions are closely

related, as observed during a 2002-3 sediment pulse and recovery along Lagunitas Creek

The most direct response was measured as changes in the percent of bed area covered with fines (<4 mm) and cobbles.

Embeddedness is less responsive to changes in sediment transport.

Both bed-condition monitoring or bedload transport monitoring can tell us whether sediment loads are likely to be affecting habitat values.

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if:

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established,

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the

sediment source (gage location is key)

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the

sediment source, among other considerations. Bed-condition monitoring is advantageous when:

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the

sediment source, among other considerations. Bed-condition monitoring is advantageous when:

Only once-a-year or less frequent monitoring is required or feasible,

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the

sediment source, among other considerations. Bed-condition monitoring is advantageous when:

Only once-a-year or less frequent monitoring is required or feasible, Minimal migration or downstream mobility of bed segments, and/or

Conclusion

The choice of using bedload-transport or bed-condition monitoring to describe changes in habitat is a significant decision for a biologist.

Bedload transport gaging is generally favored if: Sediment-rating curves have been established, Intra-season or multi-year variability must be tracked, and/or Where management depends upon clear demonstration of the

sediment source Bed-condition monitoring is advantageous when:

Only once-a-year or less frequent monitoring is required or feasible, Minimal migration or downstream mobility of bed segments, and/or Volunteers are available

Questions?