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Title: Fish resources and water quality of an in-stream gravel excavation pit in the Naugatuck River, Connecticut
Authors: Kasul, Richard L. (Richard Lawrence)
Killgore, K. Jack
Baker, John A.
Keywords: Salmonidae--Connecticut--Naugatuck River
Fishes--Effect of habitat modification on
Sand and gravel industry--Environmental aspects
Naugatuck River (Conn.)
Publisher: Environmental Laboratory (U.S.)
U.S. Army Engineer Waterways Experiment Station.
Series/Report no.: Technical Report;EL-90-1
Abstract: The fish assemblage and various water quality parameters were sampled during 18-22 July 1988, at a 1,550-m-long in-stream gravel excavation pit and three adjacent riffles located on the Naugatuck River about 6 km south of Thomaston, CT. The purposes of the study were to determine the quality of fish resources in the pit and to evaluate the potential of this habitat for supporting trout and Atlantic salmon. Sampling took place during a low-water period when water quality was expected to most greatly stress the fish community. On 21 July, upstream water flowed into the pit with a temperature of 21.2 °C, a dissolved oxygen concentration of 8.5 mg/l, and an ammonia concentration of 0.70 mg/l. Water quality conditions in the surf ace waters of the pit were similar to upstream water, but hypolimnetic water occurring in areas of the pit deeper than 5 m was found to have reduced dissolved oxygen (1.3 to 2.3 mg/l) and elevated ammonia (to 3.00 mg/l) concentrations. High levels of total copper (0.02 to 0.04 mg/l) were detected in water samples analyzed for heavy metals. Eighteen species of fish were collected from the excavation pit and nearby riffles. The pit supported large numbers of yellow perch, largemouth bass, and white sucker. The adjacent riffles supported juvenile white sucker, juvenile largemouth bass, and small riverine taxa such as tessellated darter, longnose dace, blacknose dace, and fallfish. No trout were collected in the excavation pit or nearby riffle areas, but one specimen of a migratory species, the American eel, was collected in the pit. Fish collected for comparison from a headwater reach of the Naugatuck River approximately 30 km upstream from the excavation site included two additional species, brook trout and chain pickerel. Benthic invertebrates collected from riffles above and below the pit included 23 and 24 taxa, respectively. Samples from both riffles were dominated by hydrophyschid caddis fly larvae. Next most abundant were mayflies in the upper riffle and midge larvae in the lower riffle. Hilsenhoff Biotic Index values of 5.1 in the upper riffle and 5.3 in the lower riffle were indicative of generally good water quality with some organic pollution. During the low-flow summer period, water quality in the excavation pit appears to be marginal for trout and other coldwater species requiring relatively high dissolved oxygen concentrations and low water temperatures. While wastewater treatment has improved water quality conditions in the river, high levels of ammonia and copper persist. Current conditions are adequate to support piscivorous fishes such as yellow perch and largemouth bass. Introduced trout and salmon would probably experience high predation levels near the excavation site. The pits could probably be managed most successfully for lacustrine species in an overall management plan that included salmonid introductions in more suitable reaches of the river.
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