Huron, Ontario, Michigan, Erie and Superior: the North American Great Lakes cover 151,278 km2. An expanse of water whose horizon cannot be seen, and because of their vastness they are known as "freshwater seas." Their importance becomes clear if you take a quick look at the data: 97 percent of the Planet's water is salty.
Of about 3% of the freshwater on Earth, most is trapped in Arctic ice caps or underground and, therefore, inaccessible. Of what remains, 20 percent is found in the Great Lakes and provides drinking water for about 48 million people. Yet this vital resource is contaminated by a toxin produced by a massive algal bloom caused by nitrogen and phosphorus from sewage, industrial effluent and agricultural residues being released into their crystal clear waters. To make matters worse, climate change: increasingly frequent and heavy rainfall saturates sewer systems increasing the amount of contaminated water discharged into the Great Lakes, and increasing water temperatures increase toxic algal blooms.
All this we find out while, in Italy, the Po River salt wedge has risen 40 km due to extreme drought. Newspapers headline "The Great River is no more." I wonder if it will be the same thing they will write, in a few decades, about that ocean of fresh water that are the Great Lakes and which, today, are devastated by pollution and the invasion of alien species introduced by large ships.
To know more on the topic, we suggest you to read Life and Death of the Great Lakes, by Dan Egan
I'm pleased you've made good use of the book. It has done more good in your hands than it ever would have had I kept it. We enjoyed visiting with you at Sleeping Giant Provincial Park. I've been following the two of you online, you're doing a great job of raising awareness regarding environmental issues. Keep up the great work!
Darin