Planktonic Algae

The green color of many lakes in Lake County is the result of planktonic algae, a type of microscopic algae that floats in the warm, upper layer of the water column where it can receive adequate light. This surface “scum” can also be brown or red in color.

Algae Bloom
Planktonic algae are a normal part of every natural lake, but can reach nuisance levels if nutrients, especially phosphorus, become elevated in the water column. When this happens as a result of nutrient-laden runoff or nutrient release from lake sediment, an algae bloom can occur. The bloom causes the water to turn green and significantly reduces water clarity.

Reducing Nutrient Concentration
The most effective way to reduce algae blooms is to reduce the nutrient concentration in the water. This may be as easy as addressing the nutrients directly entering the lake through a creek, but typically, the nutrients are entering the lake via overland flow (non-point runoff) or via the sediment, which are much harder to control.

Reducing Non-Point Sources of Nutrients
However, there are ways to help reduce non-point sources of nutrients. These include reducing the amount of fertilizer applied to manicured lawns or using a low phosphorus fertilizer, and establishing buffer strips between manicured lawns and the lake shore.

Maintaining Healthy Aquatic Plant Community
An additional way to reduce the frequency and severity of algae blooms is to maintain a healthy aquatic plant community in the lake. Aquatic plants compete with algae for light and other resources, while stabilizing bottom sediment to prevent nutrients from entering the water during sediment re-suspension. So if you keep your plants, you can reduce your algae.