Drinking Water in Michigan -- Where do we get it?

Where does your drinking water come from? f you live in some of Michigan's largest metropolitan areas, your drinking water probably comes from the lakes or rivers that make this state a water wonderland. But, if you live in rural areas, or in cities such as Lansing, Kalamazoo, Battle Creek and even some burgeoning Oakland County suburbs outside of Detroit, you get your water from the ground beneath your feet -- from groundwater that flows through layers of sand and gravel deposited by glaciers or siphoned from even more ancient craggy limestone and sandstone bedrock. The current quality of our groundwater -- the water held by layers of sand and gravel or rock beneath the ground like a sponge -- is very good in Michigan. In many rural areas, public and private groundwater wells provide water that is consumed and enjoyed with little or no treatment. But groundwater quality is at risk because of contamination threats from many common urban, industrial and farm practices. More than 1,300 sites of groundwater contamination have been documented so far in Michigan. Those sites were the primary drinking water source for area residents, who were left to find alternate sources of clean, safe drinking water. That's why the Groundwater Education in Michigan (GEM) project, funded by the W.K. Kellogg Foundation, is educating schoolchildren, public officials, homeowners, farmers, businesses and developers about the importance of protecting our groundwater, to insure safe drinking water. But keeping our groundwater free from pollutants also helps rivers, lakes and streams stay cleaner. Groundwater and surface water are intricately connected. Groundwater supplies the base flow for rivers and streams and, in turn, aquifers that hold groundwater like a sponge are recharged by rain and snow percolating into the earth. The amount of water on the planet earth has remained fairly constant over the eons. The water that surrounds us or that trickles underground essentially has been recycled over and over again from prehistoric times. Dinosaurs drank the same water we are drinking today. Sand and gravel deposited by glaciers can retain and transmit groundwater and are a good source for groundwater wells. Areas of the state with heavy clay deposits, usually the bottoms of extinct glacial lakes, do not readily supply groundwater for drinking. If you live in an area thick with clay deposits, such as Detroit and its suburbs, the Saginaw Valley or the "tip of the mitt," groundwater is not easily accessible. The water that clay retains moves at an exceptionally slow rate. Some communities in the eastern U.P. also sit atop thick deposits of clay left behind by glacial lakes. However, in some of these areas wells can be dug to tap sandstone aquifers located beneath the clay deposits. Water flows more quickly through a sandstone or gravel aquifer than through shale or clay. In a coarse sand aquifer, groundwater may move as quickly as three to five feet per day -- movement that helps filter the water and readily replenish a well. But a clay layer, on the other hand, may slow groundwater flow to less than one inch per day -- far from enough to sustain a well. Much of southeastern Michigan around Detroit drinks water harnessed and treated from the Detroit River and Lake Huron. This area has thick deposits of clay underneath the surface, which don't readily transmit groundwater.

Even so, 25 percent of Oakland County residents, many of them in fast-growing Detroit suburbs, receive their water from groundwater. Oakland County sits atop sand and gravel hills that are ideal porous containers for groundwater, which in turn supply the springs and wetlands that have become the sources of the Clinton, Huron, Shiawassee, Flint and Rouge rivers. But the very porous nature that makes Oakland County's aquifers such ideal groundwater suppliers also leaves them highly vulnerable to contaminants and pollution. Much of the lower peninsula is covered by sand and gravel deposits beneath the earth's surface, and their sponge-like qualities contribute to a plentiful supply of groundwater aquifers for many communities. In the northern half of the lower peninsula, these layers of sand and gravel measure 400 to 800 feet deep. In the lower peninsula's southern half, the sand and gravel accumulations generally are less than 400 feet thick. Areas in Michigan with layered deposits of sand and gravel, which can sustain many groundwater aquifers at varying depths, are the northern part of the lower peninsula near Cadillac, Houghton Lake and Higgins Lake; and in southwestern Michigan around the Kalamazoo and Battle Creek areas, and a swath of land from Hillsdale County through Washtenaw County to north-central Oakland County. But in areas where groundwater recharges easily, it also can be contaminated easily. That has happened in Plainfield as well as in the village of Comstock in southwestern Michigan near Kalamazoo, where residents were forced to use bottled water to drink and brush their teeth when industrial contaminants leaked into their groundwater supply. In the Huron River Valley, the cities of Ann Arbor and Brighton, and the Villages of Chelsea, Dexter, Pinckney, Milford and South Lyon draw their drinking water supplies from wells. But this vital resource is threatened. Leaking underground storage tanks, transportation spills, improper pesticide and fertilizer applications, and poorly-managed residential and commercial developments all have potential adverse impacts on groundwater quantity and quality. In Ypsilanti, for example, a municipal well was closed in 1996 because of contamination from a nearby dump. Another Ypsilanti well field, abandoned earlier this decade because of contamination, is surrounded by 18 underground storage tanks, two junkyards, and other facilities that leach contaminants. In the 1980s, inspections of drinking water supplies for Pleasant Plains Township in northwest Michigan revealed significant amounts of perchloroethylene and trichloroethylene in the groundwater. According to the Environmental Services Division of the State Departments of Commerce and Natural Resources, investigators found that the solvents were coming from leaking storage lagoons used by a local laundromat. In some areas of Michigan, water wells are drilled into limestone or sandstone bedrock that sits beneath deposits of sand, gravel or clay. If the bedrock is porous, with cracks and crevices, then it can be a good conduit for fresh groundwater. Bedrock aquifers are tapped for drinking water in the Keweenaw area of the western Upper Peninsula, many areas of the eastern Upper Peninsula, the tip of Michigan's Thumb region, areas of Monroe County in the southeastern most part of the lower peninsula, and throughout many counties in south central Michigan. Not all contamination is caused by humans. Bedrock aquifers in central Michigan contain groundwater which is unfit for human consumption because it's many times saltier than the oceans. Some other natural contaminants, particularly iron, calcium and magnesium, can make water unpalatable, though safe to drink.

Institute of Water Research - MSU
Design by Alex Morese