12    THE HYDROLOGIC FRAMEWORK OF
NORTHWESTERN INDIANA: A BACKGROUND FOR
PLANNING REMEDIATION
Richard F. Duwelius, Hydrologist
U.S. Geological Survey, Water Resources Division
Indianapolis, Indiana 46278-1996
INTRODUCTION
Northern Lake County and northwestern Porter County in northwestern Indiana have undergone extensive changes during the past 150 years. This region at the southern end of Lake Michigan was, in large part, a wilderness of dunes, lakes, and marshes. By 1840, however, this began
to change when railroads pushed through the dunes and marshes, and settlements grew in their
wake. By 1900, the advantage of bulk transport by ship on Lake Michigan and the construction
of harbors contributed to the creation of one of the largest industrialized and urbanized regions in
the United States.
For more than 100 years, steel making and petroleum refining and storing have been major industries in this region. Other industries, past and present, include meat packing, metal forging,
scrap processing, chemical manufacturing and recycling, and rail-car manufacturing. The industrialization and consequent urbanization of northwestern Indiana resulted in destruction or alteration of many of the dunes, lakes, and marshes to make land for expansion. Waste materials from
industrial and municipal sources are buried throughout the region. Disposal of waste was unregulated during much of the period of industrial and urban expansion. Although some types of liquid
wastes may have been treated prior to discharge or disposal as early as the late 1920's,1 a systematic and comprehensive approach to waste disposal was not initiated until the Resource Conservation and Recovery Act of 1976.
Much of this region is underlain by a surficial sand and silt aquifer. The U.S. Environmental
Protection Agency (USEPA) and the Indiana Department of Environmental Management
(IDEM) have identified more than 100 sites that require cleanup, including seven Superfund sites
within this region. As a result of the large potential for contamination, the number of contaminated sites, and the potential for groundwater contaminants to discharge to Lake Michigan, the
USEPA in 1991 designated Lake and Porter Counties as part of a Geographic Enforcement Initiative Area. By this designation, the USEPA acknowledged the importance of understanding the
regional hydrologic framework of this area.
In 1991, the U.S. Geological Survey (USGS) and the USEPA began investigations to provide
hydrogeologic information to assess regional groundwater flow and quality. Three investigations
have been completed: (I) a synoptic survey of water levels that included measurement of water
levels in 284 wells and at 22 surface-water sites; (2) an assessment of regional groundwater quality based on analyses of water from 69 wells; and (3) a study to map and characterize human-em-
placed fill materials within the region.
Purpose and Scope
This chapter describes three regional investigations done to characterize the hydrogeology.
groundwater quality, and fill deposits in northwestern Indiana. Results are summarized and presented in the text and figures. The chapter is divided into three sections—the first section describes the physical and hydrogeologic setting of northwestern Indiana; the second section sum-
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