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Experimentally Determined Impacts of a Small, Suction Gold Dredge on a Montana Stream
Author(s) -
Thomas Virginia G.
Publication year - 1985
Publication title -
north american journal of fisheries management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.587
H-Index - 72
eISSN - 1548-8675
pISSN - 0275-5947
DOI - 10.1577/1548-8659(1985)5<480:edioas>2.0.co;2
Subject(s) - dredging , environmental science , sediment , hydrology (agriculture) , suction , outflow , fauna , upstream and downstream (dna) , ecology , geology , oceanography , upstream (networking) , geography , geotechnical engineering , biology , geomorphology , meteorology , computer network , computer science
A small suction dredge was operated experimentally on Gold Creek in Missoula County, Montana to determine the effects of dredging on aquatic insects and the bottom habitat. A 10‐m section was dredged from bank to bank. Sampling was conducted before dredging and at upstream and downstream stations for control. The experiments were replicated at an upstream site. Significant changes (P < 0.01) in aquatic insect abundance were restricted to the area dredged; downstream areas were not affected (P > 0.05). Recolonization was substantially complete 1 month after dredging. Intergravel permeability was not significantly changed by dredging (P > 0.05). Suspended sediment concentrations during dredging were highly variable. Suspended sediment discharge averaged a maximum of 340 mg/liter at the outflow and returned to background levels within 11 m. Impacts of suction dredging on the bottom fauna appeared to be highly localized. No immediate downstream impacts were recorded other than fine sediment deposition and movement of unstable gravel beds downstream during the next year's peak flows, filling a downstream pool.