This effort was conducted as part of the Knife River TMDL (total maximum daily load) study for
turbidity, and includes data to compare invertebrate community composition, habitat structure,
and sediment deposition among Knife River sites. Macroinvertebrate, stream substrate, water
quality, and fish and invertebrate habitat data were collected from five sites along the Knife River
and its tributaries in August 2006. The study’s objectives were two-fold: first, to collect baseline
data from several locations within the Knife River watershed, which is currently listed as
impaired for turbidity; and second, to compare these data to historical data from the Knife River
watershed and other North Shore streams.
Turbidity and embeddedness affect stream invertebrates and fish by raising water temperature,
reducing search distances for visual predators, clogging or abrading delicate gill tissue, filling in
interstitial spaces among stream cobbles, and other detrimental effects. To put current data into
perspective, Knife River TMDL sample locations were compared to historical samples within the
Knife River watershed and other North Shore streams using macroinvertebrate assemblage
metrics and, for one set of samples, substrate and water physical parameters. Due to differences in
sampling methodology, macroinvertebrate metrics had to be calculated differently for comparison
with historical data.
Brady, Valerie; Breneman, Dan.
Knife River Macroinvertebrate and Sediment Survey.
University of Minnesota Duluth.
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