Algae in Atascadero Lake
Algae growth is a natural and expected part of the ecosystem in Atascadero Lake, especially during the dry, hot summer months. While it can’t be fully eliminated, the City continues to take environmentally responsible steps to help manage it.
The City does not use pesticides or herbicides to treat algae in the lake. Instead, a natural and non-toxic pond dye is applied to reduce sunlight penetration and limit photosynthesis, preventing excessive vegetation growth. In shallow areas of the lake, a probiotic treatment that releases nitrogen and binds up phosphorus is used to naturally starve out algae before they start and reduce blooms once they begin.
Although the lake is not tested routinely, when an algae bloom does occur, it is reported to the California Department of Fish and Wildlife (DFW). DFW biologists conduct sampling, and results are shared with the Regional Water Quality Control Board (RWQCB).
We remain committed to preserving the health and beauty of Atascadero Lake while following all guidance and requirements from State and local regulatory agencies.
Where does algae come from?
Our beautiful and very scenic Atascadero Lake contains numerous aquatic plants and naturally occurring algae, which provide filtration and shade and are an essential ingredient in providing a balanced aquatic environment. Unfortunately, hot summer days combined with direct sun and reduced water circulation, can create conditions which trigger certain varieties of algae to grow at an extremely rapid rate. Following periods of hot weather, Atascadero Lake routinely experiences very normal cycles of extreme algae growth, also known as algae blooms.