Officials have lifted the caution advisory for Lake Oroville’s Middle Fork, as the algal bloom that prompted the advisory has dissipated. The California Department of Water Resources initially issued the advisory on July 3 after staff observed the bloom. Testing revealed no toxins present in the samples collected. Blue-green algae, or cyanobacteria, naturally occur in ecosystems but can grow rapidly under certain conditions, such as warmer temperatures and increased nutrient loads. Such blooms sometimes produce toxins harmful to humans and animals.

Other Lake Oroville news:

• KRCR (Redding, Calif.): Caution advisory lifted for Lake Oroville’s Middle Fork
• California Department of Water Resources: News release: Lake Oroville update – August 1, 2025