Table of Contents
In 1991, the U.S. Geological Survey (USGS) began to implement a full-scale National Water-Quality
Assessment (NAWQA) program. The long-term goals of the NAWQA program are to describe the status
and trends in the quality of a large, representative part of the Nation's surface- and ground-water
resources and to identify the major natural and human factors that affect the quality of these resources.
In meeting these goals, the program will produce a wealth of water-quality information that will be useful
to policy makers and managers at the National, State, and local levels.
Studies of 60 hydrologic systems that include parts of most major river basins and aquifer systems
(study-unit investigations) are the building blocks of the national assessment. The 60 study units range
in size from 1,000 to more than 60,000 mi ²(square miles) and represent 60 to 70 percent of the Nation's
water use and population served by public water supplies. Twenty study-unit investigations were started
in 1991, 20 additional are starting in 1994, and 20 more are planned to start in 1997. The Lake Erie--Lake
St. Clair Basin was selected as one of the 20 study units to begin assessment activities in 1994.
The Lake Erie-Lake St. Clair Basin study unit
(see figure) drains a 22,300-mi ² area of northern Ohio (62
percent of the study unit), southeastern Michigan (27 percent), northeastern Indiana (6 percent), the
northern tip of Pennsylvania, and southwestern New York (5 percent). The study unit represents all of the
Lake Erie Basin in the United States and is about two-thirds of the total 30,140-mi ² area of the Lake
Erie Basin in the United States and Canada. The study unit drains to the St. Clair River (starting at the
outflow of Lake Huron) and to Lake St. Clair, the Detroit River, and Lake Erie, which is the 11th-largest
freshwater lake in the world. The study unit ends at the Niagara River, the outflow of Lake Erie. Principal
streams in the study unit include the Maumee River in Ohio and Indiana, the Sandusky River in Ohio, the
River Raisin in Michigan, and Cattaraugus Creek in New York.
Population density and growth in the Lake Erie Basin are among the highest in the Great Lakes Basin.
About 40 percent of the total population of the Great Lakes Basin lives in the Lake Erie Basin in 17 urban
areas having populations of 50,000 or more. The population of the study unit in 1990 was 9.76 million; 3.93
million reside in Ohio, 4.64 million reside in Michigan, 0.34 million reside in Indiana, 0.23 million reside in
Pennsylvania, and 0.62 million reside in New York.
Water resources in the study unit are central to the economy and culture of the region. The value of Lake
Erie and its tributaries with respect to sport fishing and related commerce was estimated to exceed $850
million in 1988. The study unit contains about 300 public recreational areas and about 90,000 acres of
inland waters for public use. Lake Erie supports the largest fresh-water fishery in the Great Lakes (an
estimated 50 million to 60 million pounds of fish are caught per year), and it is widely considered to be the
best walleye fishery in the world. Lake Erie, Lake St. Clair, and the St. Clair, Detroit, and Niagara Rivers
are vital shipping links that connect the upper Great Lakes to Lake Ontario and the St. Lawrence Seaway.
Major commodities that are shipped are coal, iron ore, limestone, metal products, sand and gravel, and
grains and soybeans.
Most of the study unit (northwestern and north-central Ohio, southeastern Michigan, and northwestern
Indiana) is in the Central Lowlands Physiographic Province (see figure).
The surficial deposits of this area
consist primarily of ground moraine and end moraine of glacial origin; valleys are filled with glacial
outwash. The area is characterized by broad, low ridges with smooth, gentle slopes separated by flat,
gently undulating plains. The Eastern Lake Section and the Till Plains Section within the province consist
of wide expanses of flat land underlain by clayey till or lake deposits; this flat land is interspersed with
sandy ridges that are remnants of glacial-lake beaches. Wetlands dominated the landscape in the
western part of the study unit before settlement. About 90 percent of the wetlands were drained for
agricultural and urban development. The only sizable remnants are the shoreline wetlands of the Ottawa
National Wildlife Refuge and Crane Creek State Park along Lake Erie and the freshwater delta marshes
of the St. Clair Flats State Wildlife Area at the mouth of the St. Clair River. Because soils are fertile and
the climate is temperate, the primary land use in this part of the study unit is agricultural, ranging from
orchards and vineyards near the Lake Erie shoreline to cropland in corn and soybeans further inland.
The easternmost part of the study unit (northeastern Ohio, Pennsylvania, and New York) is within the
Appalachian Plateaus Physiographic Province. Here, successive glaciations have subdued the relief and
buried many pre-glacial valleys. The topographic relief in this province is greater than that of the Central
Lowland Province and consists of irregular plains dissected by stream valleys. Land use is a mix of
agriculture, forest, and urban areas. Orchards and vineyards are located along the Lake Erie shoreline in
this part of the study unit because of the moderating effect of the Lake on the local climate.
From west to east, average annual temperature in the study unit is 48 to 51 degrees Fahrenheit, average
annual precipitation is 31 to 40 in. (inches), average annual surface runoff is 8 in. to 22 in., and average
water loss from evaporation and evapotranspiration is 22 to 25 in. Recharge of the ground-water reservoir
in most of the study unit is limited by overlying fine-grained soils and is only about 2 in. annually.
However, recharge can be as high as 6 in. annually in some areas.
The principal stream in the study unit, the Maumee River, drains an area of 6,608 mi², or roughly
one-third of the total drainage area of the study unit. The average daily discharge of the Maumee River is
4,990 ft ³ /s (cubic feet per second) at Waterville, Ohio. Between 1930 and 1993, the maximum streamflow
recorded was 113,000 ft³/s on March 14, 1982, and the minimum streamflow recorded was 17 ft³/s on June
30, 1988. Other principal streams and their drainage areas in Ohio are the Sandusky River (1,420 mi ², the
Cuyahoga River (809 mi ²), and the Grand River (705 mi²). Principal streams in Michigan are the River
Raisin (1,070 mi ²), the Huron River (909 mi ²), and the Clinton River (742 mi ²).
The principal stream in
New York is the Cattaraugus Creek (554 mi ²).
Principal aquifers in the study unit consist of glacial or alluvial deposits and bedrock. The glacial and
alluvial deposits are fine- to coarse-grained. The coarse-grained deposits generally consist of highly
permeable sands and gravels of glaciofluvial origin commonly found along the courses of present-day
streams. The coarse-grained deposits in the northwestern corner of the study unit underlie glacial till or
lake deposits, contain ground water that is locally confined under artesian pressure, and form aquifers
that can be highly productive. Extensive kame-terrace or other permeable glacial deposits of gravel and
sand are widely tapped as sources of ground water throughout northeastern Ohio. Bedrock aquifers
commonly consist of limestone and dolomite in the northwestern and extreme northeastern parts of the
study unit, and sandstone and fractured shale in the central part of the study unit. The U.S.
Environmental Protection Agency has designated three sole-source aquifers in the study unit: the
Catawba Island/Bass Island aquifer and the Allen County area-combined aquifer system in Ohio, and the
Cattaraugus Creek Basin aquifer system in New York.
In 1987, surface-water withdrawals in the study unit averaged about 8,250 million gallons per day. About
99 percent of the withdrawals were from Lake Erie, Lake St. Clair, the St. Clair and Detroit Rivers, and
other principal tributaries. The St. Clair--Detroit River system supplies water to 50 percent of Michigan's
population. Approximately 12 percent of the water withdrawn from the Lake Erie--Lake St. Clair Basin
study unit is used for public supply; only 6 percent of the public supply is ground water. Power generation
and industrial uses constitute 88 percent of the withdrawals, less than 2 percent of which is from ground
water. Water users inland from the lakes rely to a greater degree on ground water for domestic, industrial,
and agricultural supply than do water users near the lakes.
Recent and historical water-quality initiatives are an outgrowth of public concern about water quality.
Among these initiatives are the Great Lakes Water Quality Agreement (1976, 1984, and 1987) between
the United States and Canada, and the Great Lakes Water Quality Initiative to control toxic substances
released to the Great Lakes. Impairments to use of the water resource have been identified in 43 Areas of
Concern (AOC), and Remedial Action Plans to clean up these areas are being prepared. Eleven AOC's are
in the study unit.
Improvements in scientific knowledge are needed to improve our understanding of processes that
influence the occurrence, distribution, transport, fate, and effects of many of the contaminants of concern
in the study unit. Although much progress has been made in the Lake Erie Basin to control and mitigate
contamination and improve water quality since the early 1970's, water-quality managers must often
implement best-management practices and regulate certain contaminants on the basis of incomplete or
conflicting information. The following major water-quality issues have been identified in the Lake
Erie-Lake St. Clair Basin study unit:
Communication and coordination between the USGS and other scientific and water-management
organizations are critical components of the NAWQA program. Each study-unit investigation has a local
liaison committee consisting of a manager, who represents Federal, State, and local agencies; universities;
and the private sector. Each liaison committee will exchange information on water-quality issues of
regional and local interest, identify sources of data and information, assist in the design and scope of
project elements, and review project-planning documents and reports.
- Reproductive impairment in fish and wildlife as a result of exposure to and bioaccumulation of
contaminants such as PCB's, pesticides, methyl mercury, and other trace-element and trace-organic
- The suitability of commercial and sport fish for human consumption as a result of elevated
concentrations of PCB's and other substances in fish tissue.
- Impairment of the use of water resources for consumption and recreation and for aquatic life as a result
of the discharge of nutrients, pesticides, trace elements, synthetic organic compounds, and pathogens to
streams and lakes by way of storm runoff.
- Declines in biological diversity of aquatic communities as a result of habitat disturbance and alteration.
- Problems related to water-supply management and ecosystem management as a result of the
proliferation of nonnative species.
--- Donna N. Myers and Dennis P. Finnegan
Information on technical reports and hydrologic data related to the NAWQA program
can be obtained from
U.S. Geological Survey
6480 Doubletree Avenue, Columbus, OH 43229-1111
(614) 430-7700, or email firstname.lastname@example.org
Fact Sheet 94-056
USGS National Water-Quality Assessment (NAWQA) Program