The water we drink and use everyday might be called our most valuable resource. Agriculture, manufacturing, brewing, and other day-to-day activities depend on reliable, pure groundwater. In addition, Wisconsin's famous lakes, rivers, and streams support a large tourism economy attracting people from all over the world.
Groundwater is water that moves through the soil and rock and eventually reaches a saturated layer below the earth. Wisconsin receives an average of 30 to 32 inches of precipitation per year. About 75 percent of this precipitation evaporates or transpires through plants and never reaches our groundwater. The other 25 percent runs off the surface or soaks into the soil. The soil type directly impacts how much water runs off. Sandy soil allows for much more water to seep into it, whereas clay or hard packed soil allows more water to run off.
Marshfield's aquifers, or rock and soil that store and transmit water, range from 45 to 95 feet deep. All of the water serving the City of Marshfield is drawn from a series of 18 underground wells in and around the city. The common misconception that groundwater comes from Canada or Lake Superior in some mysterious underground stream is false. Almost all of the Marshfield groundwater pumped by Marshfield Utilities comes from a relatively small area, usually within a few miles.
It is estimated that there are over two quadrillion gallons of groundwater in Wisconsin, and this area of Wisconsin receives the most precipitation in the state. However, the Marshfield area is underlain by crystalline bedrock, a type of rock formation known for yielding only small amounts of water. Therefore, we still need to conserve water whenever possible. Per person we use an average of 63 gallons of water per day. Of this 63 gallons we use:
2.0 gallons - outdoors
6.5 gallons - washing dishes, cooking
7.5 gallons - laundry
9.5 gallons - drinking, washing hands
12.5 gallons - bathing and showering
25.0 gallons - flushing the toilet
Threats To Our Groundwater
Even though there may be plenty of surface water, finding locations in this area that hold enough groundwater to supply a large capacity of wells can be difficult. Even if there is a dependable supply of water, the water may not be drinkable due to contamination.
Gasoline, fertilizers, paint thinners, insecticides, herbicides, that are over used or abused can run into our lakes and streams or soak into the soil and contaminate our groundwater. Improperly stored agricultural and lawn products may leak from damaged or corroded containers and seep into the groundwater.
Exceeding the recommended proportion of lawn and agricultural products can soak into the groundwater or runoff into lakes and streams. Improperly disposing of empty containers can allow hazardous waste to soak into the water table.
Handling contaminants once they enter our groundwater is no small feat. If a specific source of contamination is found, there's no guarantee it can be removed economically. Contamination can often be the end result of normal day-to-day activities for all of us. Remember, what we do on top of the ground affects the water beneath it.
Poorly operated landfills and town dumps are another potential threat to our groundwater. Toxic substances in old landfills are continually being discovered to be contaminating groundwater. With properly sited, designed, constructed, and maintained landfills we can minimize contamination of groundwater. But what we dispose of in landfills can still affect groundwater and render them unusable. We must dispose of toxic and hazardous waste properly.
Sanitary sewers and septic systems leaking or malfunctioning, or the improper application of manure or fertilizer allows bacteria, nitrates, viruses, and household chemicals to contaminate groundwater. Excessive or improper application of manure and fertilizer to farm fields and urban lawns is the leading cause of nitrate contamination. Drinking water that is high in nitrates can be fatal to infants under the age of six months. We need to use common sense when applying manure and fertilizer to our fields and lawns. Do not over apply or apply on slopes of land that can create runoff.
Abandoned wells and mines are a direct channel to our groundwater. They allow water that collects surface pollutants and treatments to contaminate the groundwater in and around these areas. If not properly handled by sealing and capping, abandoned wells are very difficult to locate as a source of contamination and can pose a threat for many years.
Leaking underground storage tanks, most used to store gasoline, diesel fuel, and oils, slowly corrode and release their contents into the soils and rocks. These leaks may be discovered early, but some could leak for years. Spills and illegal dumping of chemicals pose a serious threat to clean drinking water. These groundwater contaminants are difficult and costly to clean up.
Natural threats to groundwater are the minerals occurring naturally in soils and rocks. These minerals dissolve in the groundwater, giving it a particular taste, odor, or color. Radium, manganese, and sulfur can be found in Wisconsin's wells at varying levels. Normally they are not a safety threat. Only very high levels of some of these elements such as radium or radon gas pose a health risk.
Your water utility continually tests drinking water to meet or exceed the state drinking water standards. The water department is required by law to test for bacteria, organic and inorganic compounds, and other contaminants. An elaborate treatment system makes Marshfield's water among the best in Wisconsin. If you have further questions about your city water, please contact Marshfield Utilities at 387-1195.
What Can Be Done To Preserve And Protect Our Groundwater?
Dispose of household toxic waste properly. Do not dump them down the drain, on your lawn, driveway or down a storm drain. Store toxic products in a safe manner and save them for a hazardous material Clean Sweep.
Reduce or eliminate the use of lawn pesticides and fertilizers. Water your lawn slowly and less often. Water at night to decrease evaporation.
Reduce, Reuse, and Recycle as much as possible. Less garbage in our landfills means less harmful materials that can leach into our groundwater.
Use less water. Install low flow shower heads, fix leaky faucets and fixtures, install aerators on faucets. Wash dishes by hand, using a dishwater for larger loads.
Fill and cap abandoned wells.
The above information researched and developed with the assistance of the Marshfield Area Chamber of Commerce's 1996 Leadership Marshfield groundwater education project group.