This is the Four Corners Power Plant and the lake with which it cools its machinery. This coal-burning plant, along with one just 20 miles north, are two of 20 such plants in the US, and these two are among the worst in terms of emmissions control. They are dumping thousands of tons of harmful chemicals into the air every year, including mercury that causes severe health problems for the inhabitants for dozens of miles around. This is a national sacrifice area. All of the wildlife is dead or gone.
Morgan Lake is warm year-round, and can be too hot to swim in during the summer. When the sun is on it, it is a sickly green.