Although some people like to look down to the bottom of the lake and exclaim at how clear and clean it is, that is not always the sign of a healthy lake. A certain amount of weed and algae growth provides habitat and food for fish. It is a balancing act to keep the environment suited for fish, yet not overgrown.
Lawn and garden fertilizers can cause an overgrowth of vegetation in the lake. That occasional foam you see gathering on the lake shore during storms is composed of phosphates contained in fertilizer and detergents. Here again we need some help from the residents who surround the lake. It is important to be prudent in the use of lawn fertilizers. Because your yards slope to the water, fertilizers can end up in the lake. In general, liquid fertilizers are the best idea if you must fertilize. Because they are absorbed rapidly, there is less chance of runoff. Granular fertilizers, on the other hand, take much longer to be absorbed, and can be washed into the lake very easily by watering or rainfall.
And, if you own a dog, make sure you pick up dog droppings daily. In the same way as fertilizer wash-down, rain and watering will carry contamination from dogs into the lake.