HYDROLOGY

Water is an abundant but unevenly distributed resource. Without water industry cannot exist and without expandable water resources industry cannot grow. These are inescapable facts which will shape the development of the country in the future as they have in the past.  Michigan is no exception in this regard. More fortunate than most states in its ground and surface water supply, it must still resolve a number of problems before its full potential can be realized.
    Michigan receives about 30 inches of precipitation each year. Nearly 22 inches are transpired by plants or evaporated from ground and water surfaces: the remainder, 8 inches of depth annually, are our primary water supply. Michigan has a primary supply estimated to equal 10 inches of depth over its entire area.
    Water, essential for human life, is abundant in Michigan both on the surface and as groundwater contained in the glacial mantle and the sedimentary bedrock of the state. As the population has grown, so has the demand on the available water. Many cities, industries, and homes rely on the four Great Lakes that border Michigan. It is estimated that Michigan’s future need for water from the bordering Great Lakes may increase fivefold in the next fifty years. Such an increase would have ramifications for industry, tourism, agriculture, and almost all other economic sectors of the state.
    Michigan is justly called a "hard water" state. "Hard" water contains a lot of calcium carbonate. Hard water requires more soap than does soft water, to get the same amount of bubbles and cleaning. Most it Michigan’s waters, whether taken from ground water supplies or from rivers, are "softened" for domestic use and usually require treatment for industrial processing or boiler use. For cooling or air conditioning "raw" water is usually suitable with treatment.

Sources of Water
Michigan has three main sources of freshwater: (1) precipitation, of which there is a fair amount; (2) the Great Lakes, and (3) the water found in the pore of rocks and sediment that form the landforms of the state and in the underground rock formations. Michigan as a state averages about 31 inches (78.7 cm) of precipitation a year, which would total about 325 million cubic meters of water a day. Some of the precipitation seeps into the ground to become a part of the groundwater supply, some is almost immediately returned to the atmosphere by evaporation, and most runs into lakes and rivers that, in turn, drain into the Great Lakes.
    Whether water becomes surface runoff or groundwater depends upon a number of factors. Sandy soils, gravels and some rock types contribute to groundwater flows, whereas clays and impermeable rocks contribute to surface runoff. Water falling on sloped areas tends to run off rapidly, while water falling on flat areas tends to be absorbed or stored on the surface. Vegetation also tends to decrease surface runoff; root systems hold moisture-laden soil readily, and water remains on plants.
    Taken together, Michigan’s streams and groundwater give it a potential more favorable than is indicated by the tabulation of primary water supply alone, and yet fail to state the case in full. For Michigan is embraced on both sides by the largest fresh water bodies in the country. Water from the Great Lakes may readily be carried inland long distances as they are in Detroit and Grand Rapids. The supply of fresh water from the Great lakes is relatively unaffected by seasonal changes and is, with proper treatment, at all times potable and chemically suited for processing. Impediments to the use of Great Lakes water are economical and political rather than physical.
    The amount of freshwater in the Great Lakes is almost staggering. This water in utilized by coastal communities, and some is piped a considerable distance inland. The Great Lakes bordering Michigan represent part of the largest inland supply of freshwater in the world. All five Great Lakes account for 95% of the surface freshwater in the United States.
    Water supply needs vary considerably over the state, and in some areas the drain is larger than the supply, requiring, the importation of water such as from the Great Lakes. Water is the resource Michigan’s industry needs the most of , whether by weight or by volume. More people in the state mean greater requirements for food, industry, and services, which means a greater demand for water. The daily per capita need for water increases with the growth of population and technology. Modern, irrigated farming, paper processing, and the production of automobiles also demand large amounts of water.
    There are water shortages from time to time in parts of the state, not only because of increased demand on the existing supply, but also because of pollution or because water is drawn more rapidly than nature replaces it. Occasional summer droughts cause a rationing of water or a reduction in the amount used for less essential purposes like watering lawns. Potential solutions to such shortages are water conservation measures, building more pipelines from the Great Lakes to interior cities, and keeping the rivers and lakes clean in all parts of the state.

Parts of the text on this page have been modified from L.M. Sommers' book entitled, "Michigan: A Geography", and from the NOAA Publication, "The Great Lakes An Environmental Atlas and Resource Book" (1995).

This material has been compiled for educational use only, and may not be reproduced without permission.  One copy may be printed for personal use.  Please contact Randall Schaetzl (soils@msu.edu) for more information or permissions.