1. 1 Placer County Water Agency Middle Fork American River Project AQ 3 – Aquatic Mollusk Technical Study Report – 2008 March 3, 2009

2. 2 Conduct 2008 Mollusk Field Studies Document 2008 Mollusk Findings in the AQ 3 - Aquatic Mollusk Technical Study Report - 2008 Determine the presence or absence of three special-status mollusk species and identify potentially suitable habitat for these species. Conduct Drift Sampling No Contingency Studies Needed, Based on Consultation with TWG Consult with Aquatic TWG Discuss Contingency Sampling Based on Water Quality (AQ - 11) Results Document 2007 Findings in the AQ 5 - Bioenergetics Technical Study Report - 2009 Document 2007 Findings in the AQ 3 - Macroinvertebrate and Aquatic Mollusk Technical Study Report - 2007 Conduct CSBP Benthic Sampling at the Ralston Afterbay Sediment Management Project Monitoring Sites Conduct SWAMP Benthic Sampling Document the benthic macroinvertebrate (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 the BMI community in the bypass reaches downstream of each large reservoir. Document the BMI community in areas with known water quality issues, if any are identified in the AQ 11 - TSP. 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. Conduct 2007 Macroinvertebrate Field Surveys Aquatic Mollusk Study Objectives Macroinvertebrate Study Objectives

3. 3 2008 Mollusk Study Sites Representative Habitat Study Sites Comparison Study Sites Incidental Mussel Observation Study Sites

4. 4 Distribution Surveys for Aquatic Mollusk Species Approach Conducted surveys for 3 special-status mussel and snail species California floater (Anodonta californiensis) Scalloped juga (Juga (Calibasis) occata) Great Basin rams-horn snail (Helisoma newberryi) Surveys included identification and abundance estimates for all aquatic and incidental terrestrial mollusks

5. 5 Aquatic Bivalves (Mussels and Clams) Found at the Study Sites Scientific Name Common NameTypical Habitat Habitat Where Found Photograph Margaritifera falcata Western pearlshell mussel Burrowed in sand and gravel substrate near the top of pools or in lower velocity portions of runs. Pisidium casertanum Ubiquitous peaclam Has a nearly cosmopolitan distribution and is widely adaptable to a broad range of habitats. Burrowed in sand/silt in edgewaters and eddies. Pisidium walkeri Walker peaclam Typically found in creeks and rivers with slow currents and small lakes with soft mud bottoms. Burrowed in sand/silt in edgewaters and eddies. Pisidium species Burrowed in flocculent silt/organic matter permeated by spring/seep inflow along the stream margins.

6. 6 Aquatic Gastropods (Snails) Found at the Study Sites Scientific Name Common NameTypical Habitat Habitat Where Found Photograph Ferrissia rivularis Creeping ancylidAquatic pulmonate (i.e., air breathing) snails that acquire oxygen through their mantles and can thus occupy calm, warm, and often stagnant water where dissolved oxygen concentrations are low. Attached to gravels and cobbles in shallow edgewaters. Fossaria obrussa Golden fossaria Attached to rocks or woody debris in shallow, warm edgewaters. Menetus opercularis Button spriteAttached to cobbles and boulders in shallow spring and tributary inflow areas. Physella gyrina Tadpole physaAttached to rocks or woody debris in warm, low-velocity areas. Juga (Oreobasis) nigrina Black juga or smooth river juga A prosobronch snail that has retained the ancestral gilled oxygen uptake and thus requires clean, well oxygenated waters. Attached to rocks or woody debris in flowing water or edgewaters receiving spring inflow.

7. 7 Key Findings Special-status Species Mollusk Species No live specimens or shells were found at any of the study sites Aquatic Mollusk and Incidental Species 4 bivalve species (Margaritifera falcata and 3 peaclams) and 5 gastropods were found in the study sites Most are common native species that occur throughout North America 5 native terrestrial gastropod species and the signal crayfish (not native) were found in the study sites Distribution Surveys for Aquatic Mollusk Species

8. 8 Distribution and Abundance of Aquatic Bivalves in the Study Sites

9. 9 Distribution and Abundance of Aquatic Gastropods in the Study Sites

10. 10 Distribution and Abundance of Aquatic Mollusks in the Study Sites

11. 11 Distribution and Abundance of Aquatic Mollusks in the Study Sites

12. 12 Distribution and Abundance of Aquatic Mollusks in the Study Sites