More than 700 of Wisconsin’s lakes, streams and rivers are polluted to a greater or lesser extent, leading to damaged ecosystems, fish kills and cases of people falling ill every year (see Reference 1). One of the main causes of the fish kills is not a surge of toxic chemicals — although dangerously high levels of toxins such as mercury are found in some of Wisconsin’s water bodies — it is nutrient pollution. Beneficial as nutrients might be in the right place, in the wrong place and at high levels, they can be deadly.
Phosphorus and nitrogen are essential nutrients for plants, and for algae. When large amounts of either nutrient wash into lakes, rivers and seas, there is an immediate response, usually in the form of algal blooms. Some forms of algae are toxic – people fall ill in Wisconsin from blue-green algae poisoning every year – but the main problem is not the algae themselves, it is what happens when they die. Bacteria break down the dead algae, removing oxygen from the water in the process. The result is deoxygenated water, which is lethal to fish and other forms of aquatic life.
Runoff, whereby pollutants and silt from surrounding agriculture, industry and domestic residences washes into lakes and rivers, produces much of Wisconsin’s water pollution. In the case of livestock farms, high levels of nutrients are produced in the waste. Arable farming uses fertilizers and pesticides, sometimes to excess. Industrial activities release pollutants ranging from heavy metals to nitrogen. Bass Lake is an example of an affected lake. Until recently it had very high levels of phosphorus, which led to algal blooms, oxygen depletion and fish kills, mainly in winter, when ice prevents any transfer of fresh oxygen from the atmosphere. Controls on pollution, mainly nutrient pollution, in and around the lake have allowed it to recover in the last few years (see Reference 2).
Although agriculture and industry might be the main sources of water pollution, they are not the only ones. Runoff also carries pollutants from the most mundane activities. Your day-to-day chores could contribute anti-freeze, pet waste, spilt motor oil and a range of other pollutants (see Reference 3). Stormwater drains in Wisconsin do not lead to water treatment facilities; they lead directly to lakes and rivers (see Reference 4). Air pollution from motor vehicles adds to water pollution because the pollutants don’t all stay in the atmosphere.
How to Help
To lessen your own impact, simple lifestyle changes make a difference. In the garden, minimize your use of pesticides and fertilizers or avoid them altogether. In the house, reduce use of toxic cleaning chemicals or choose milder alternatives such as vinegar. Driving less also helps; driving adds to air pollution, which in turn exacerbates water pollution. If you want to play a more active part in improving your local waterways, consider volunteering. For example, the Wisconsin Department of Natural Resources (see Resource 1) needs volunteers to monitor pollution levels in lakes.
Judith Willson has been writing since 2009, specializing in environmental and scientific topics. She has written content for school websites and worked for a Glasgow newspaper. Willson has a Master of Arts in English from the University of Aberdeen, Scotland.
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