Pesticides and the Environment
What is non-point source pollution?
Non-point source (NPS) pollution, also called polluted runoff, occurs when water (from rain, snow, or even watering your lawn) runs off land, taking with it pollutants like lawn chemicals, deposits from car exhaust, and animal wastes, and carries these pollutants to bodies of water. According to the EPA, NPS pollution is the current leading cause of water quality degradation in the U.S.
Runoff from urban areas is especially problematic because of impervious surfaces, such as streets and rooftops, and manicured lawns, which absorb less rainwater than other types of vegetation. In many parts of Greater Milwaukee, this runoff enters the storm sewer system. Although many people believe that water from the storm sewers goes to a water treatment plant, it is important to note that in most parts of Greater Milwaukee, the storm sewers deliver this polluted water directly into Lake Michigan and its tributaries, like the Milwaukee River.
NPS pollutants contribute to beach closings and degradation of our drinking water. Besides the direct effects of polluted runoff on Lake Michigan water quality, high levels of stormwater runoff also overtax the sanitary sewer system, contributing to combined sewer overflows that further pollute Lake Michigan. To learn more about sewer overflows click here: MMSD on Sewer Overflows.
You can learn more about storm water and urban runoff in Wisconsin from the University of Wisconsin-Extension: Polluted Urban Runoff - a source of concern.
How do lawn care practices affect our waterways?
Improper watering can lead to runoff that carries pollutants into rivers and lakes. Watering an established lawn is often unnecessary. During the hottest part of summer, most grasses in this region naturally go dormant, and will recover in the fall. During this time, watering sporadically or too lightly can do more harm than good. When you must water, do so slowly to avoid runoff. (Clay soils may require watering in two or more cycles to increase absorption.) Learn more about proper lawn irrigation from the following UW-Extension publication:
Spreading fertilizer on impervious surfaces or bare soil greatly increases the likelihood of it being carried into waterways. When phosphorus from lawn fertilizers reaches a waterway, it stimulates algae overgrowth, which deprives aquatic wildlife of oxygen, leading to fish kills. When you use fertilizer, always keep it off of sidewalks, driveways, streets, and bare soil. For information on how to properly fertilize, click on the following UW-Extension Lawn and Garden Fertilization publication:
Pesticides can be washed off lawns by rain or irrigation, and can percolate through the soil to groundwater. The risk of pesticides entering the water supply is increased when a given chemical is persistent (resists breaking down) or water soluble. Many people are surprised to learn that some pesticides linger in the soil for weeks or even months. (We are often given a false sense of security by the state-mandated pesticide warning signs, which can be removed after less than 48 hours.)
Learn more about the movement of pesticides in the environment, including persistence of these chemicals in soil, by reading this article from the Extension Toxicology Network at Cornell University:
What can I do to protect Wisconsin Rivers and Lakes?
There are plenty of steps we can all take to protect our Wisconsin rivers, lakes and our great Lake Michigan. If you have read the above information, you already know the negative impact poor yard care choices can have on our waterways, and what changes you can make. Your changes can have a great impact as you set an example of safer, healthier yard care practices in your neighborhood. Our Lawn Care Calendar and Tips for safe watering, fertilizing, and weed control methods will help you care for your lawn in an environmentally friendly way.
Avoid directing downspouts onto impervious surfaces. If your downspouts are connected to the sanitary sewer system, contact your municipality to learn about options for them, so that the rainwater from your roof can be filtered by the soil instead of entering the water treatment system, where it can overtax the system and contribute to basement backups and sewer overflows. In Milwaukee, visit this MMSD link for information:
Finally, consider installing a rain garden and rain barrels to capture your rainwater before it becomes polluted runoff.
