Shallow ground-water flow, water levels, and quality of water, 1980-84, Cowles Unit, Indiana Dunes National Lakeshore

Water-Resources Investigations Report 85-4340

National Park Service



The Cowles Unit of Indiana Dunes National Lakeshore in Porter County, northwest Indiana, contains a broad dune-beach complex along the southern shoreline of Lake Michigan and a large wetland, called the Great Marsh, that occupies the lowland between the shoreline dunes and an older dune-beach complex farther inland. These lacustrine sediments form a surficial aquifer that extends from the Lake Michigan shoreline to the northern edge of the Lake Border moraine.

Water levels and water quality in the surficial aquifer were monitored from 1977 to 1984 near settling ponds on adjacent industrial property at the western end of the Cowles Unit, Seepage from the settling ponds from 1967 to 1980 created a water-table mound that extended north into the shoreline dune complex and caused perennial flooding of several intradunal lowlands on National Lakeshore property. Since 1980, when the settling-pond bottoms were sealed, these intradunal lowlands contained standing water only during periods of high snowmelt or rainfall.

Water-level declines following the cessation of seepage ranged from 6 feet at the easternmost settling pond to nearly 14 feet at the westernmost pond. No general pattern of water table decline was observed in the Great Marsh or in the shoreline dune complex at distances greater than approximately 3,000 feet east or north of the settling ponds.

Since the settling ponds were sealed, the concentration of boron has decreased while concentrations of cadmium, arsenic, zinc, and molybdenum in shallow ground water downgradient of the ponds show no definite trends in time. Arsenic, boron and molybdenum have remained at concentrations above those of shallow ground water in areas unaffected by settling-pond seepage.

Study Area

Additional publication details

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Publication Subtype:
USGS Numbered Series
Shallow ground-water flow, water levels, and quality of water, 1980-84, Cowles Unit, Indiana Dunes National Lakeshore
Series title:
Water-Resources Investigations Report
Series number:
Year Published:
U.S. Geological Survey
Publisher location:
Indianapolis. IN
Contributing office(s):
Indiana Water Science Center
iv, 25 p. :ill., maps ;28 cm.
United States
Other Geospatial:
Indiana Dunes National Lakeshore
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