Middle Fork Project AQ 3

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Middle Fork ProjectAQ 3 Macroinvertebrate and
Aquatic Mollusk Technical Study Report Overview

• May 5, 2008

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Macroinvertebrate Study Objectives and Related
Study Elements and Reports
Study Objectives Document BMI community in the
peaking reach and compare to adjacent bypass and
comparison reaches to characterize general
habitat conditions. Sample BMI community at
long-term USDA-FS sampling sites to supplement
existing data sets. Document BMI community in
the bypass reaches downstream of each large
reservoir. Document BMI community in areas with
known water quality issues, if any are identified
in the AQ 11 - TSP. Determine presence or
absence of three special-status mollusk species
and identify potentially suitable habitat for
these species. Document seasonal density and
size distribution of drifting macroinvertebrates
in selected bypass reaches and the peaking reach
for input to bioenergetics growth and habitat
modeling.
Conduct 2007 Field Surveys
Conduct SWAMP Benthic Sampling
Conduct CSBP Benthic Sampling at the Ralston
Afterbay Sediment Management Project Monitoring
Sites
Conduct Drift Sampling
Document 2007 Findings in this Macroinvertebrate
Report
Consult with Aquatic TWG
Discuss Contingency Sampling Based on Water
Quality Results
If Necessary, Develop Recommendations and Prepare
Contingency Studies
Document 2007 Findings in the Bioenergetics
Report (2009)
Complete 2008 Mollusk Field Studies and
Contingency Studies (if necessary)
Document 2008 Mollusk and Contingency Study
Results in Macroinvertebrate Report (2009)
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Study Objectives

• Document the BMI community in the peaking reach
  and compare to adjacent bypass and comparison
  reaches to characterize general habitat
  conditions.
• Sample the BMI community at long-term USDA-FS
  sampling sites to supplement existing data sets.
• Document BMI community in bypass reaches
  downstream of each large reservoir.

4
Study Objectives

• Document the BMI community in areas with known
  water quality issues, if any, as determined in
  the AQ 11 TSR.
• Document the seasonal density and size
  distribution of drifting macroinvertebrates in
  selected bypass reaches and the peaking reach for
  input to bioenergetics growth and habitat
  modeling (2009 AQ 5-TSR).
• Determine presence or absence of 3 special-status
  mollusk species and identify potentially suitable
  habitat for these species (2009 AQ 3-TSR).

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Potential Contingency Studies

• Additional BMI Sampling
• Coordinate with the AQ 11 Water Quality TSP to
  identify any additional SWAMP sampling locations
  based on water quality results
• AQ 11 Water Quality
• Implement SWAMP to quantify BMI species
  compositions, abundance, and distribution at
  locations where potentially adverse water quality
  issues may exist or are identified by the water
  quality sampling program.
• Develop sampling to address potential water
  quality issues in consultation with the Aquatic
  TWG.

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Macroinvertebrate Study Sites
14 SWAMP Sites 7 RASMP (CSBP) Sites
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BMI Metrics

• Multi-metric index of biotic integrity (IBI)
  (Rehn 2008)
• ET taxa richness
• Percent intolerant individuals
• Percent tolerant individuals
• Percent Non-insect taxa
• Percent predator individuals
• Percent scraper individuals
• Shannon diversity

• Individual metrics consistent with the RASMP
  (2000-2006)
• Invertebrate density
• Taxa richness
• EPT ratio
• Percent Chironomidae
• California Tolerance Value
• Functional feeding groups
• Dominant taxa

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Survey Results

• Longitudinal Trends in BMI Community Metrics
• Comparison of Peaking Reach and Adjacent Bypass
  and Comparison Reaches
• Above and Below Diversions
• Bypass Reaches Below Large Reservoirs
• Long-term BMI Sampling Sites

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Average August 2007 Temperatures
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Longitudinal Trends in BMI Community Metrics

• Hydropower TRC IBI scores were higher (indicated
  better biological conditions) at the higher
  elevation and colder water sampling sites than at
  the low elevation and warmer water sampling sites
  (i.e., the hydropower IBI was correlated with
  elevation and temperature).

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Comparison of Peaking Reach with Adjacent Bypass
and Comparison Reaches

• In combination, the hydropower TRC IBI and
  individual metric scores indicated lower
  biological conditions at the top of the Middle
  Fork American River peaking reach immediately
  below Ralston Afterbay Dam (MF24.4) and
  immediately below Oxbow Powerhouse (MF23.6),
  compared to the adjacent bypass and comparison
  sites.
• At sites downstream from the top of the peaking
  reach (MF20.9 to MF4.8) biological conditions
  (IBI and individual scores) were similar to those
  in non-peaking comparison sites (unimpaired
  comparison rivers and Middle Fork American River
  and Rubicon River immediately upstream of Ralston
  Afterbay), although some variability occurs based
  on the individual metric examined

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Above and Below Diversions

• In 2007, hydropower IBI scores were slightly
  higher upstream from the diversions than
  downstream.

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Bypass Reaches Below Large Reservoirs

• Hydropower IBI scores were relatively high and
  within the range of those observed in unimpaired
  river reaches above hydropower reservoirs by Rehn
  (2008).

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Long-term BMI Sampling Sites

• RASMP Locations (2000-2007)

• At all the sampling locations, inter-annual
  variability in the individual metrics and the
  relative abundance of the different functional
  feeding groups was high.
• Since 2001, the BMI communities in the two sites
  immediately downstream from Ralston Afterbay and
  Oxbow Powerhouse (MF 24.4 and MF 23.6) had poorer
  individual metric scores than the sites farther
  downstream in the peaking reach and in the
  adjacent non-peaking bypass and comparison
  reaches.
• Since 2001, in the two most downstream sites in
  the peaking reach, the BMI communities had
  slightly lower taxa richness than the non-peaking
  bypass and comparison river reaches (lower
  biological condition).
• However, EPT index values were greater and
  California Tolerance values were lower compared
  to the non-peaking bypass and comparison river
  reaches (better biological condition).
• Since 2001, chironomid midges have been one of
  the most abundant taxa at most of the sampling
  sites during the annual sampling (particularly
  MF24.4 and 23.6).

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Long-term BMI Sampling Sites

• South Fork Long Canyon Creek

• Hydropower IBI scores have slightly increased
  since 1999.

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Long-term BMI Sampling Sites

• Duncan Creek

• Hydropower IBI scores have varied over time.

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Comparison of Peaking Reach with Adjacent Bypass
and Comparison Reaches

• Hydropower IBI and individual metric scores in
  the peaking reach (RM 20.9 to RM 4.8) are similar
  to sites in the Middle Fork American and Rubicon
  Rivers immediately upstream of Ralston Afterbay
  and comparison streams, although some variability
  of individual metrics occurs.

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Long-term BMI Sampling Sites

• RASMP Locations (2000-2007)

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Long-term BMI Sampling Sites

• RASMP Locations (2000-2007) Functional Feeding
  Groups