During summers, small neighborhood ponds can get a little green. But that green doesn't mean the pond has poor water quality. Naturally, most people assume green on a lake or pond is algae, but often the green on top of your water is actually duckweed. Also known as duck’s meat or water lentil, duckweed is actually tiny, free floating native plants. The plants are found in clusters of leaves, each with small roots that hang down into the water. It can form thick green blankets on the water’s surface which is why it is often mistaken for algae. Duckweed is found in quiet waters of ponds, lakes and streams and will rarely become abundant on waters with frequent wind or lots of wave action.
Other sources of green color include blue-green algae, or cyanobacteria, which can be harmful with prolonged or frequent exposure. Algae blooms are caused by heat and excessive amounts of nutrients such as nitrogen and phosphorus. Some of the most common sources of nutrients include fertilizers, grass clippings, and animal waste.