1. Connecticut River Habitat Restoration: A Significant Population of Rare Mussel Species? and Paul. Boison Northeast Utilities Service Company James W. Athey Jr., Nathan Henderson, Jennifer Doyle-Breen Metcalf & Eddy Inc.

2. 2 Northeast Utilities Service Company Acting as agent for Holyoke Water Power Company Project Support

3. 3 Presentation Outline Holyoke Coal Tar Project Background Coal Tar Excavation Methods Project Mitigation Measures Methods Results Rare Mussel Species Conclusions

4. 4 Project Background 1990: coal tar leachate was observed discharging into the Hadley Falls tailrace Suspected source: Holyoke Gas Works, an historic manufactured gas plant (1852 -1951) Habitat for federally endangered shortnose sturgeon and protected mussel species

5. 5 Coal Tar Remediation 9 coal tar patch locations in Site Portion 1 (north) 2 coal tar patch locations in Site Portion 2 (south) NOAA, MA DEP mandated remediation Remediation plan developed by Metcalf & Eddy in 2001 Removal work conducted in 2002, 2003, and 2005 Dry and wet excavation methods

6. 6 Wet Excavation Excavator transported to site on a barge Containment area enclosed with siltation boom Excavated material loaded onto skiff and transported to shore for off-site disposal

7. 7 Dry Excavation Containment area enclosed with portable cofferdam Work area dewatered Excavated material transported off site for disposal

8. 8 Limited time frame for construction Silt curtains and portable cofferdam structures Water quality sampling program Removal of fish and mussels within containment areas Construction Mitigation Measures

9. 9 Methods Subsurface exploration for juvenile rare mussels Mark mussels prior to relocation Relocate mussels to relocation areas Recapture surveys Establish relocation areas (outside of work areas) Mussel removal by SCUBA diving and snorkeling

10. 10 Buffers and Mussel Relocation Areas Establish buffer areas –2002: 100 feet on all sides –2003: 100 feet downstream / 20 feet elsewhere –2005: 50 feet downstream / 20 feet elsewhere Establish relocation areas –Surveyed opposite side of river for suitable habitat –Six relocation areas identified

11. 11 Mussel Removal After work areas were identified (60 feet from coal tar edge), buffer areas marked with anchored buoys Mussel removal between weighted transect lines –2002-2003: All mussels –2005: All rare species and common 1.5” and greater (NHESP requested) Collected, counted and identified all mussel species

12. 12 Subsurface Exploration Additional requirement by NHESP Attempt to collect juvenile rare mussels 6 mm screen Dedicated areas Randomly selected areas

13. 13 Mark-Recapture Survey 2002-2003 - All Mussels –Krylon paint mark –2-part epoxy –One/two year recapture survey Goal: Determine the general success of the relocation effort 2005 Only Rare Mussels –Numbered tags –One week and one month recapture surveys

14. 14 Mussel Relocation Results Four species collected in study area (From left to right) –Tidewater mucket (Ligumia ochracea)- MA Species of Special Concern –Yellow lampmussel (Lampsilis cariosa)- MA Endangered –Eastern Elliptio (Elliptio complanata)- Common –Alewife floater (Anodonta implicata) (bottom)

15. 15 Mussel Relocation Results (Cont.) 2005 subsurface exploration: -No juvenile rare mussel species collected -1 Adult Tidewater mucket -415 Adult Elliptio/526 Juvenile Elliptio

16. 16 Example of Rare Mussel Distribution

17. 17 Mark-Recapture Survey 2002 – 2003 Results: Over 15,000 mussels marked 868 recaptured in 2004 Up to 88% survival for Elliptio No rare mussels recaptured 2005 Results: One week survey – approx 38% mussels found One month survey – approx 10% mussels found Two mortalities discovered (one tidewater mucket and one yellow lampmussel) – cause undetermined

18. 18 Rare Mussel Species Well-established populations of yellow lampmussels and tidewater muckets Density of rare mussel species is encouraging –Sandy bottom habitat (0.09/100m 2 ) –Cobble bottom habitat (0.02/100m 2 ) Extrapolated population over 4-mile stretch of river 87 to 4,000 lampmussels Previously only two known sighting of lampmussels below Holyoke Dam

19. 19 Rare Mussel Species Populations are reproducing Documented reproductive behavior Water quality and habitat improving in Connecticut River Due to immense size of Connecticut River and potential available habitat, likely substantial populations along other sections of the river Recently documented populations above the Holyoke Dam and further downriver

20. 20 Conclusions Mussel relocation was successful at removing 26,000 mussels from 2002 to 2005 Documented significant populations of rare mussel species Mussel densities are variable but rare mussel densities generally higher in coarse sandy substrate Despite short-term disruption from coal tar excavation, mitigation measures successful, which furthers the overall project goal of long-term aquatic habitat restoration

21. 21 Comments and Questions