Middle Fork Project AQ 3 – Macroinvertebrate and Aquatic Mollusk Technical Study Report Overview

1. Middle Fork ProjectAQ 3 – Macroinvertebrate and Aquatic Mollusk Technical Study Report Overview May 5, 2008

2. Macroinvertebrate Study Objectives and Related StudyElements 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)

3. 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).

5. Potential ContingencyStudies • 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.

6. Macroinvertebrate Study Sites 14 SWAMP Sites 7 RASMP (CSBP) Sites

7. 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 BMI Metrics

8. 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

9. Average August 2007 Temperatures

10. 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).

11. 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

12. Above and Below Diversions • In 2007, hydropower IBI scores were slightly higher upstream from the diversions than downstream.

13. 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).

14. 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).

15. Long-term BMI Sampling Sites • South Fork Long Canyon Creek • Hydropower IBI scores have slightly increased since 1999.

16. Long-term BMI Sampling Sites • Duncan Creek • Hydropower IBI scores have varied over time.

17. 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.

18. Long-term BMI Sampling Sites • RASMP Locations (2000-2007)

19. Long-term BMI Sampling Sites • RASMP Locations (2000-2007): Functional Feeding Groups