Environmental Impact Assessment(EIA) Registration for the ...

REVISED PROJECT DESCRIPTION AND ENVIRONMENTAL IMPACT ASSESSMENT (EIA) REGISTRATION
FOR THE NEPISIGUIT FALLS GENERATING STATION MODIFICATION AND REHABILITATION PROJECT
The river reach impounded by the NFGS (i.e., the headpond) is approximately 4 km long and
90 m to 160 m wide. The headpond has a surface area, at full supply level, of approximately
56 ha. Below the falls, a river width of 70 m to 110 m is common, although narrower sections of
25 m to 50 m width are found in areas where river grades are steeper. River widths of 70 m to
100 m are also common in the reach above the headpond. The river is for the most part
bedrock controlled, and quite shallow, except near the generating station where the forebay has
been artificially deepened in order to provide a small amount of water storage, as well as
hydraulic head for power generation. The spillway dam has a sill at approximately 96.0 m
(315 ft) elevation in relation to the NFGS site datum.
Normal operating range of the headpond during the summer months is approximately 104.1 m
to 104.2 m (341.5 ft to 342 ft), with the minimum operating level of 103.9 m (341 ft) and a
maximum headpond elevation of approximately 105.5 m (346 ft)—with all measurements in
relation to the NFGS site datum. The headpond elevation with the main rubber dam deflated
would be approximately 100.9 m (331 ft), which would be similar to the natural the run-of-theriver
elevation.
This indicates a normal (operating) water depth of at approximately 3.4 m (11 ft) at the face of
the spillway dam. Assuming that the river bed in some areas may be as much as 2 m below the
sill at the spillway, the normal water depth in the deepest parts of the headpond is not likely to
be greater than about 6 m.
In 1969, a spill of waste from the former Bathurst Iron Mine into the Nepisiguit River just
upstream from the NFGS resulted in a large kill of juvenile salmon in the lower portion of the
river. Salmon catches between 1970 and 1975 appear to have been substantially depressed;
however, the river appears to have recovered by 1980 (based on data presented in Locke et
al. 1997).
Research of existing documentation, and consultation with DFO as well as local fisheries
groups, was undertaken to confirm the fish community present in the Nepisiguit River. The
Nepisiguit River is Atlantic salmon (Salmo salar) bearing downstream of the falls; however, the
falls present a natural barrier to fish passage and no anadromous species are found upstream
of the falls or the NFGS. The species assemblage above the NFGS consists of brook trout
(Salvelinus fontinalis), white sucker (Catostomus commersonii) and various other coarse fish
species such as dace and minnow (R. Baker, pers. comm. 2010; DFO 2010; Scott and
Crossman 1998). Additionally, American eel (Anguilla rostrata) are likely able to navigate the
dam and falls as elvers and are known to be upstream of the facilities (R. Baker, pers. comm.
2010; DFO 2010; Scott and Crossman 1998). There is no known presence of smallmouth bass
in this reservoir, unlike other larger reservoirs in the province (Hatch 2008; R. Baker, pers.
comm. 2010).
Brook trout are reported to overwinter in the headpond, but move upstream in May-June to
occupy better habitat during the summer, and in preparation for spawning in the fall (R. Baker,
pers. comm. 2010). There is a brook trout fishery in and upstream of the headpond during May-
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