By George D. Casey, Donna N. Myers, Dennis P. Finnegan, and Michael E. Wieczorek
The Lake Erie-Lake St. Clair Basin covers approximately 22,300 mi ²(square miles) in parts of Indiana, Michigan, Ohio, Pennsylvania, and New York. Situated in two major physiographic provinces, the Appalachian Plateaus and the Central Lowland, the basin includes varied topographic and geomorphic features that affect the hydrology. As of 1990, the basin was inhabited by approximately 10.4 million people.
Lake effect has a large influence on the temperature and precipitation of the basin, especially along the leeward southeast shore of Lake Erie. Mean annual precipitation generally increases from west to east, ranging from 31.8 inches at Detroit, Mich., to 43.8 inches at Erie, Pa.
The rocks that underlie the Lake Erie-Lake St. Clair Basin range in age from Cambrian through Pennsylvanian, but only Silurian through Pennsylvanian rocks are part of the shallow ground-water flow system. The position of the basin on the edge of the Michigan and Appalachian Basins is responsible for the large range in geologic time of the exposed rocks. Rock types range from shales, siltstones, and mudstones to coarse-grained sandstones and conglomerates. Carbonate rocks consisting of limestones, dolomites, and calcareous shales also underlie the basin. All the basin is overlain by Pleistocene deposits- till, fine-grained stratified sediments, and coarse-grained stratified sediments-most of Wisconsinan age. A system of buried river valleys filled with various lacustrine, alluvial, and coarse glacial deposits is present in the basin.
The soils of the Lake Erie-Lake St. Clair Basin consist of two dominant soil orders: Alfisols and Inceptisols. Four other soil orders in the basin (Mollisols, Histisols, Entisols, and Spodosols) are of minor significance, making up less than 8 percent of the total area.
The estimated water use for the Lake Erie-Lake St. Clair Basin for 1990 was 10,649 Mgal/d (million gallons per day). Power generation accounted for about 77 percent of total water withdrawals for the basin, whereas agriculture accounted for the least water-use withdrawals, at an estimated 38 Mgal/d. About 98 percent of the total water used in the basin was drawn from surface water; the remaining 2 percent was from ground water.
Agricultural and urban land are the predominant land covers in the basin. Agriculture makes up approximately 74.7 percent of the total basin area; urban land use accounts for 11.2 percent; forested areas constitute 10.5 percent; and water, wetlands, rangeland, and barren land constitute less than 4.0 percent.
The eight principal streams in the basin are the Clinton, Huron, and Raisin Rivers in Michigan, the Maumee, Sandusky, Cuyahoga, and Grand Rivers in Ohio, and Cattaraugus Creek in New York. The Maumee River, the largest stream in the basin, drains 6,609 mi² and discharges just under 24 percent of the streamflow from the basin into Lake Erie. Combined, the eight principal streams discharge approximately 54 percent of the surface water from the basin to the Lake Erie system per year. Average runoff increases from west to east in the basin.
The glacial and recent deposits comprise the unconsolidated aquifers and confining units within the basin. Yields of wells completed in tills range from 0 to 20 gal/min (gallon per minute), but yields generally are near the lower part of this range. Fine-grained stratified deposits can be expected to yield from 0 to 3 gal/ min, and coarse-grained stratified deposits can yield 0.3 to 2,050 gal/min. Pennsylvanian sandstones can yield more than 25 gal/min, but they generally yield 10 to 25 gal/min. Mississippian sandstones in the basin generally yield 2 to 100 gal/min. The Mississippian and Devonian shales are considered to be confining units; in places, they produce small quantities of water from fractures at or near the bedrock surface. Wells completed in the Devonian and Silurian carbonates yield 25 to 500 gal/min, but higher yields have been reported in several zones.
Most streamwater in the Lake Erie-Lake St. Clair Basin is moderately hard to very hard as a result of contact with carbonate-containing materials. The softest water is found in small streams in far northeastern Ohio and in western New York. The hardest water is found in streams in southeastern Michigan and certain streams in western New York, near Buffalo.
The amounts of nitrogen and phosphorus fertilizers, herbicides and insecticides, and sediment discharged to Lake Erie from its basin are higher than the amounts discharged from any other basin of the Great Lakes. Although trends in phosphorus concentrations over the combined period 197590 for the Raisin, Maumee, Sandusky, Cuyahoga, and Grand Rivers have been downward, trends in nitrate-N concentrations for the Raisin, Maumee, and Sandusky Rivers have been upward. Pesticides have been detected in streams draining row-cropped areas after application and runoff in the spring and early summer. Peak concentrations of atrazine can range from much less than 1.0 µg/L (microgram per liter) in samples collected during preapplication runoff to 35 µg/L or more in samples collected during postapplication runoff.
Most ground water in the Lake Erie-Lake St. Clair Basin is moderately hard to very hard as a result of contact with carbonate bedrock and surficial materials of similar origin. The softest ground water is found in relatively shallow, unconsolidated aquifers in western New York, and the hardest water is found in carbonate and sandstone aquifers of the basin. Although water contained in glacial deposits is typically lower in concentrations of dissolved solids and major ions than water contained in bedrock, ground water and surface water are both dominated by calcium, bicarbonate, and sulfate ions.
Concentrations of nitrate plus nitrite-N in ground water greater than or equal to 3 milligrams per liter have been detected in a small percentage of wells sampled in certain areas of the Lake Erie-Lake St. Clair Basin. Currently used pesticides have been detected, but only rarely, generally at concentrations less than 0.1 µg/L.
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