Q: Why are some lakes I see full of algae and thick plants?

A: First of all, plants naturally grow in and around lakes. Maybe you're asking about a lake that is being choked off by too much algae. In many cases, humans are responsible. Actually, these lakes are being fed too much food for plants! There are certain chemicals we use that are nutrients (food) to plants. At our homes we fertilize our yards with nitrogen, potassium, and phosphorus. These chemicals wash off our lawns and eventually get into the water system, such as into creeks, rivers, and lakes. Once there, algae and plants have a feast on this "food." Things used to be worse for our water bodies. Phosphorus used to be an ingredient in our laundry detergent, but this has generally been phased out.