Each year the Minnesota Department of Natural Resources (MNDNR), Division of
Fisheries, assesses the walleye population in Mille Lacs Lake to provide a forecast for the
upcoming fishing season. Water temperature is a controlling factor in the estimate.
Because water temperature measurements in Mille Lacs Lake are only available for
recent years, the MNDNR requested simulations of daily water temperatures for Mille
Lacs Lake from 1983 - 2002. Temperatures in September and October were of particular
MINLAKE 96, a one dimensional, unsteady water quality model was employed to
simulate the water temperatures. Weather data from Brainerd and Duluth, were used as
input. Water temperature measurements from 2000 to 2002 were used to validate the
It was detennined that the weather data from Brainerd provided the best simulation for
the summer, fall and winter. However, the Duluth data offered a better estimate for the
Since the walleye assessment takes place in September of each year, the Brainerd
simulation should provide the best water temperature estimates. For the years when the
Brainerd data is not available, the Duluth measurements can be used with a correction
Minnesota Department of Natural Resources, Division of Fisheries
Fang, Xing; Matzek, William; Stefan, Heinz G..
Daily Water Temperature Simulations for Lake Mille Lacs (1983-2002).
St. Anthony Falls Laboratory.
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