Local Runoff Leads to River Deadzones
At the local level, the effect can be hard to see. We do not generally apply too much fertilizer to our small yard, especially when compared to the acerage of a large farm. But there are many lawns. And each lawn, after each rain, will lose some of its soil and any chemical in the soil to the small streams that surround us. The contaminated rainwater finds its way into larger streams, then rivers, and eventually into the Mississippi river.
We have just moved from the local effect of fertilizers and pesticides--a beautiful lawn, to the global effect. When hundreds of thousands of acres of fertilized lawns and farms converge on the largest watershed in the USA, the watershed will contain the accumulated fertilizer and pesticides.
You can see how beautiful the Mississippi river looks from far away. But when we take a closer look we see the real effect of the chemicals on the water and the life that should be found in it.
The fertilizers and pesticides greatly increase the amount of nitrogen and phosphorous in the water. Algie thrives on these elements. But a large bloom of algea will create a spike in the amount of oxygen in the water reaching levels that do not sustain other life. This creates what is called the "Dead Zone" at the mouth of the Mississippi.
The effect is not as great in the winter months. Most people do not fertilize in the fall as heavily and much of the rain water water is stored in snow and the mountains. When spring comes, homeowners and farmers begin to fertilize again, and by the time summer roles around, the rain has washed the chemicals to the mouth of the Mississippi. The blooms, represented as red in the images, increases.
Our actions upstream effect the environment downstream. One simple option people have to act locally and help the global environment is to let their grass grow longer. 3 and 1/2 to 4 inches is recommended. Your lawn will be more healthy, if this is all you do. Also, there are a veriety of organic and less-harmfull alternatives to fertilizers and pesticides. Corn Gluten Meal is one example.
Good luck with your lawns, and now you know what you do may affect people living down stream.