Chapter Title

Effectiveness of two different surface bypass facilities on the Connecticut River to pass emigrating Atlantic salmon (Salmo salar) juvenile salmonids


B N. Hanson

Publication Date



Atlantic salmon, bypass, Connecticut River, juvenile, salmon, surface bypass, fish passage, New England Power, Bellows Falls, hydroelectric, smolt, bypass systems, Vernon Station, forebay, downstream fish passage, efficiency, upstream, canal, diversion, entrance, skimmer, tailrace

Start Page


End Page


Book Title

Innovations in Fish Passage Technology


Odeh M;

Publication Place

Bethesda, MD


American Fisheries Society


New England Power Company constructed downstream passage facilities at theVernon and Bellows Falls Hydroelectric Stations on the Connecticut River as part of a 1990agreement with the Connecticut River Atlantic Salmon Commission to provide safe, and timelydownstream passage for emigrating Atlantic Salmon (Salmo salar) smolts. These passagewaysare very different in terms of hydraulic and structural characteristics and they offer a strikingcontrast in the success of their respective surface bypass systems.Vernon Station is run-of-the-river with nominal generating capacity of 27 MW. Total discharge isup to 325.64 m3/s at normal operating head of 10.4 m. A log/ice boom forms an inner forebayand diverts floating debris and ice to a sluice at the eastern end of the powerhouse. Initially, thisboom and sluice was the only downstream fish passage facility, other than spill gates. Over the course of six years, 1990-1996, studies of radio-tagged emigrating salmon smolts wereconducted at the Station. Resultant data were used to facilitate modifications and additions to theStation to provide safe, expeditious downstream passage. A 25 m long, surface fed fishpipebypass was installed through the powerhouse in late 1990 and studied for two years. A louversystem to guide smolts to the fishpipe and an alternate surface bypass was constructed in 1993and studied in 1994, 1995, and 1996. Bypass efficiency was improved and the agenciesapproved Vernon's downstream facilities for current Station configuration.Bellows Falls Hydroelectric Station is 51.5 km upstream of Vernon. A 196 m long by 13 m highdam diverts the river down a 470 m long canal to the powerhouse. Total turbine discharge isapproximately 287.3 m3/s. An existing wooded log/ice boom was replaced in 1994 with a fixedconcrete diversion boom that extends at a 45o angle from one side of the power canal to theentrance of a sluice. The boom is 62.8 m long and extends 4.6 m underwater at normalimpoundment elevation. Water passes through the sluice over a regulated skimmer gate througha 76 m straight-walled concrete tunnel. Elevation drops approximately 9 m along the sluice andat the end, water falls from a height of 9 m into the tailrace. This diversion boom systemsuccessfully bypassed 94.4% of all radio-tagged salmon. After only one year of study, in 1995,(at least three years were initially required), the agencies approved the Bellows Falls downstreamfacility.

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