A stream may seem like something small when thinking about what’s going on with Lake Michigan but those streams are important. Understanding what a watershed is, exactly, helps us understand that what we do impacts more than just our immediate location. A watershed is ALL the land, above and below the surface, where water that runs off/out of it ends up at one point. We all live in a watershed. You’ve probably seen the signs along highways saying that such and such and area is part of a watershed. What that means is that whatever we put onto the ground in that area or into the water ends up in our larger bodies of water, including Lake Michigan. When we hear about a body of water that’s polluted we tend to think of industry or perhaps farms causing that pollution but we need to remember that we contribute as well. In fact pollution directly from something such as a factory discharging into water is only 25% of the pollution (point source pollution). The remaining 75% is from the land use in a watershed.
How do we contribute? One way is what we put on our lawns or gardens. Nitrogen and phosphorous are ingredients in chemical fertilizers. They are also something that the Riverwatch group tests for in waterways. Just like these chemicals promote the growth of plants and grasses, they increase the growth of algae in water. This algae grows too fast, causing plant death. As the plants die and decompose, the oxygen in the water decreases and fish can die. (One extreme example is the dead zone in the Gulf of Mexico)
The picture at the right from NOAA shows this area and it's dissolved oxygen (DO) level (something else Riverwatch tests). For aquatic life to be happy the DO needs to be at least 5 ppm. On the picture that doesn't start until the lightest shade of green.
People can help to reduce their impact on the water in their area by avoiding chemical fertilizers. If possible, using native plants in your yard is a good idea. Check out Clear Choices Clean Water for details on ways to do this. To find environmentally friendly lawn care products, I recommend Clean Air Gardening.
Some of the other sources of phosphorous include manure from farm field run off or human waste from failing septic tanks or from municipal treatment discharge. A further source of phosphorous is detergents, so much so that many states are enacting bans on phosphates in detergents. This is good for the environment but many people complain their dishes aren't as clean. I've found that a product called Lemi Shine works WONDERS for cleaning dishes and removing hard water stains.
As far as nitrogen, the ways to reduce phosphorous help but the main source of nitrates in Indiana water is sewage. Unfortunately the only way to reduce that source is infrastructure investment and improvements, something I am not going to address at this time but if you want to understand some of the issues with it check out the movie "The Crumbling of America" from the History Channel. I don't see it on Netflix but it still comes on the History Channel occasionally.
I hope this post gives you some things to think about. Remember, no matter what size, we all have an impact on the environment and every little bit we can do to lessen that helps.
I live in NW Indiana. Indiana probably brings to mind corn and flat land but there is more than that here. Southeastern Indiana has the beautiful Clifty Falls State Park while northwestern Indiana in on the shore of Lake Michigan. Lake Michigan, for those who don't know, is on the of the five Great Lakes. These lakes hold 1/5th of the entire world's fresh water and provide drinking water to tens of millions of people in the US and Canada. They also provide recreation and tourism to people around the world. Unfortunately, the health and beauty of these natural wonders is being threatened
PCBs and mercury are contaminants that collect in soil, water, and microscopic animals. Mercury goes up the food chain as the these microscopic animals are eaten by larger animals and those animals eaten by larger ones and so on. PCBs mainly reside in the fat of a fish but mercury is bound to the muscle, the part of the fish we eat. This is a definite concern for those who fish in Lake Michigan. One tributary to the lake, the Grand Calumet River, is so polluted that the state of Indiana says not to eat any fish from it. Period. Lake Michigan itself has many other fish that are so full of mercury or PCBs that pregnant women and children under the age of 15 are told not to eat them and the rest of the population is told to only eat once every month or two. (2010 Indiana Fish Consumption Advisory Complete Report)
The pollution of Lake Michigan is a concern for the surrounding states. The water in it is retained for 99 years. What was dumped years ago is still there. What we dump now will be there long after we are gone. So what can one do? There are some groups, including the Sierra Club, who offer ways we can help. Here are some links to them:
Sierra Club Great Lakes Program
Alliance for the Great Lakes
National Wildlife Federation