Three-quarters of the cities in the United States use groundwater as part of their water supply. Almost 350 municipalities throughout Michigan use groundwater for their public water supply system.
All citizens of Kalamazoo County rely upon groundwater for their drinking water. Whether or not your home is connected to a municipal water supply or to a small well located on your property, you are drinking groundwater.
So you might ask, where does groundwater come from? It comes from the rain! Each year in Kalamazoo County we get an average of 34-36 inches of rain. Approximately 65% of the rain is lost to evapotranspiration (evaporation and plant use), 25% infiltrates into the ground to become groundwater (water trapped between particles of sand and gravel underground) and 10% runs off to surface water.
Water moves through the environment in a continuous cycle called the hydrologic cycle. Water evaporates from lakes, streams, the Great Lakes and oceans. Water is also given off in large amounts by trees and other vegetation. This moisture returns to the earth as precipitation. As rain and snowmelt flow across the surface of the soil, some of the water flows into streams and lakes and becomes surface water. A large portion of the water however seeps into the ground. Water that seeps below the surface is groundwater, your source of drinking water. Below is a graphic depicting the hydrologic cycle.
The surface of Kalamazoo County includes 576 square miles (or 368,640 acres), thus the total amount of water recharged to the groundwater system is approximately 73-98 billion gallons per year. However, it doesn't just stay in the ground. It is constantly moving through the soils towards the nearest stream, lake or river. At any one time hydrogeologists estimate that we have in excess of about 270 million gallons of water per day. (Source: Groundwater Education in Michigan, Western Michigan University) Current county-wide usage is estimated at about 55 million gallons of water per day.