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-BreenMetcalf & Eddy Inc.

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Northeast Utilities Service CompanyActing as agent for Holyoke Water Power Company

Project Support

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Presentation Outline

• Holyoke Coal Tar Project Background

• Coal Tar Excavation Methods

• Project Mitigation Measures

• Methods

• Results

• Rare Mussel Species

• Conclusions

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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

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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

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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

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Dry Excavation

• Containment area enclosed with portable cofferdam

• Work area dewatered

• Excavated material transported off site for disposal

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• 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

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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

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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

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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

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Subsurface Exploration

• Additional requirement by NHESP

• Attempt to collect juvenile rare mussels

• 6 mm screen• Dedicated areas• Randomly selected areas

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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

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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)

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Mussel Relocation Results (Cont.)2002 2003 2005

Area Surveyed

4.2 acres

10.6 acres

20.4 acres

Alewife floater 0 3 11 14

Tidewater mucket

0 2 8 10

10,455

TOTALS

25,955

53Yellow lampmussel

0 13 40

Eastern Eliptio

454 15,046

• 2005 subsurface exploration:- No juvenile rare mussel species collected

- 1 Adult Tidewater mucket

- 415 Adult Elliptio/526 Juvenile Elliptio

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Example of Rare Mussel Distribution

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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

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Rare Mussel Species

• Well-established populations of yellow lampmussels and tidewater muckets

• Density of rare mussel species is encouraging– Sandy bottom habitat (0.09/100m2)– Cobble bottom habitat (0.02/100m2)

• Extrapolated population over 4-mile stretch of river 87 to 4,000 lampmussels

• Previously only two known sighting of lampmussels below Holyoke Dam

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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

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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

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Comments and Questions