CASE STUDY
Holyoke Hydroelectric Project
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Holyoke Gas and Electric Company –
City of Holyoke and Town of South Hadley, Massachusetts
BACKGROUND
At river mile 86, the Holyoke Hydroelectric Project is the first dam on the Connecticut River encountered by endangered shortnose sturgeon moving upstream
from the estuary. An area of about 8,309 square miles is drained by the river at
the Holyoke Dam. The Project consists of a 30-foot
oot
high, 985-foot long dam topped by five 3.5-foot
ot
high inflatable rubber dam sections and a Bas-cule Gate at the south end of the dam; a threelevel canal system extending through the lower
areas of the City of Holyoke and providing water for industrial and hydropower generation; sixx
hydroelectric generating stations; and fish passage
age
shortnose sturgeon
facilities. Hadley Falls Station (30 MW), is the largest of the hydroelectric generating stations included in
the Project (43.8 MW total), and is located at the southwest end of the dam. The
project impounds a 2,290-acre reservoir with a normal maximum surface elevation
of 100.6 ft National Geodetic Vertical Datum (NGVD).
In the northern extent of their range, shortnose sturgeon exhibit three distinct migratory movement patterns associated with spawning, feeding, and overwintering
activities. In spring, pre-spawning shortnose sturgeon move from overwintering
grounds to spawning areas. The Connecticut River population of shortnose sturgeon spawn from late March to late May. Sturgeon spawn in upper, freshwater areas
and feed and overwinter in both fresh and saline habitats.
THE PROBLEM
The endangered shortnose sturgeon inhabit the Connecticut River from spawning grounds upstream of the Holyoke Project to foraging grounds below the project. Available information suggests there may be two spawning sub-populations of
shortnose sturgeon in the river, one isolated and self-sustaining group above Holyoke Dam and a separate group below the dam. NOAA Fisheries, the federal agency
NORMANDEAU ASSOCIATES
E N V I R O N M E N T A L
C O N S U L T A N T S
responsible for protecting the species, is concerned that the Holyoke Dam inhibits
the downstream population from accessing upstream spawning grounds, and the
upstream population from accessing downstream foraging grounds.
As a requirement of their FERC license to operate the Project, Holyoke Gas and
Electric Company (HG&E) is tasked with determining the approach and passage
route(s) of radio-tagged downstream migrating shortnose sturgeon. Knowing where
and how sturgeon pass the dam will give HG&E the data needed to design effective
downstream passage for sturgeon while minimizing cost.
THE SOLUTION
Normandeau set up 13 radio telemetry monitoring stations around the Holyoke
Project, as depicted below, to detect the approach and passage of radio tagged
shortnose sturgeon. Arial Yagi antennas were used, antenna type and size varied
depending on site-specific requirements. Receivers used for the study were datalogging Lotek SRX_400 receivers. Information recorded and stored in the receivers
included date, time of day, tag identification, average signal strength, and detection
location. Delineation of reception range
was achieved prior to commencement of
the sampling effort.
Three years into the five-year study, 40 fish
have been tagged with radio transmitters.
Though some problems with tag failure
and tag shedding have been encountered,
no tagged fish have entered the study area.
Schematic of area near Holyoke Dam with radio telemetry monitoring station detection areas.
Manual tracking was targeted for approximately 12 - 24 hours after tagging to locate
fish, and again approximately 7 - 10 days after tagging to verify tag function, identify post tagging locations, and monitor short-term movements. Most tagged fish
only made small movements and resided in discrete areas. The longest movements
observed were all downstream, by five fish that were all captured and tagged in midMay. Their downstream movement ranged from 8.3 to 25.0 river miles. Onset of
their movement was just after tagging and release. This, in addition to the fact that
nine other sturgeon were taken in the same net, suggests that perhaps these fish were
in the process of a post-spawning migration.
REFERENCES
Kynard, B. 1997. Life history, latitudinal
patterns, and status of the shortnose sturgeon, Acipenser brevirostrum. Environmental Biology of Fishes 48:319– 334.
Kynard, B., M. Kieffer, M. Burlingame, and
M. Horgan. 1999. Studies on shortnose
sturgeon. Final Report to Northeast Utilities
Service Company, Berlin, Connecticut, and
City of Holyoke, Holyoke, Massachusetts.
The habitat available to adult shortnose sturgeon for spawning, summer foraging,
and wintering has been described as capable of supporting an estimated 300–400
adult shortnose sturgeon; the population of adult fish in the collection area was
estimated at approximately 300 (Kynard 1997). Numbers of those that might pass
downstream of Holyoke Dam in any year is difficult to predict. In ten years of radio
telemetry studies, Kynard et al. (1999) estimated that 0 to 30% of tagged adults
passed in the same year as the spawning season in which they were tagged. These
percentages, along with the population estimate noted above, resulted in estimated
downstream passage numbers ranging from 0 to 90. Additional data generated over
the remaining two years of study will assist HG&G in moving forward toward minimizing the affect of the dam on the shortnose sturgeon’s downstream migration.
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