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Water Quality in the Middle Great Lakes: Results of the 1985 U.S.
EPA Survey of Lake Erie, Huron and Michigan
EPA-905/6-89-001
April 1989
David C. Rockwell- U.S. Environmental Protection Agency
Douglas K. Salisbury - Computer Sciences Corporation
Barry M. Lesht - Argonne National Laboratory
Great Lakes National Program Office
United States Environmental Protection Agency
230 South Dearborn Street
Chicago, Illinois 60604
DW89931897-01-0
Final 1985
Abstract
Continuing a limited annual program begun in 1983, the Great
Lakes National Program Office survey was completed during January
and February, and the three ship surveys were conducted in spring,
summer, and fall. The samples were analyzed for traditional
limnological parameters and nutrients. Although many measurements of
water quality were unchanged from 1983 to 1985, the physical
conditions, notably temperature, were much different; 1983 was a
mild year, while 1984 and 1985 were much colder. In 1985, the
stratification for each lake spanned a longer period than in 1983
and 1984. All lakes exhibited a pattern of nutrient depletion from
the epilimnion and concurrent enrichment of the hypolimnion during
the summer. The magnitude of the depletion for some parameters was
greater in 1985 than observed in 1983 and 1984. During the fall
survey before and after Afall
overturn@ measurements
were obtained. Total phosphorus concentration continues to be low in
Lakes Michigan and Huron, and seems to declining in Lake Erie.
Nitrate + nitrite nitrogen concentrations and consistently
increasing in all lakes. Chloride decrease in Lake Erie. Chloride
concentration in southern Lake Michigan was unchanged between 1984
and 1985 which may be a significant change from the previous years
of constant increases. In response to recent historical changes in
phosphorus loading, in Lakes Michigan, Huron and Erie predicted
concentrations of total phosphorus decreased over the modeled period
using the Great Lakes Mass Balance Model.
Descriptors
Lake Michigan, Lake Huron, Lake Erie, Phosphorus, Water Quality,
Chloride, Eutrophication, Great Lakes, Models, Limnology, Nutrients
Nitrogen, Silica.
Document is available to public through the National Technical
Information Service
Springfield, VA 22161
No. of Pages - 272.
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