Answer:
runoff from a nearby hog farm
Step-by-step explanation:
Hog farming or pig farming is becoming common place today. Animal droppings are known to be rich in nitrates, phosphates as well as bacteria.
Nitrates and phosphates are essential nutrients required by algae in lake water. Hence, runoff from a hog farm supplies a lot of nutrients to lake water.
Similarly, the run off introduces enormous bacterial content that is contained in the droppings of these animals.