At least 15 lakes and ponds are under advisories or warnings for potentially dangerous cyanobacteria blooms, including Silver Lake in Belmar.
Restrictions at the advisory level include bans on swimming, kayaking, wading and eating fish caught. People are asked to keep their children and pets away from the water as well.
More commonly known as blue-green algae, potential impacts to humans include skin rashes and respiratory and gastrointestinal problems.
These blooms happen usually in the summer when the water is warm, stagnant, and rich in nutrients Runoff containing fertilizers after a heavy rain can help enhance the bloom.
The advisory will remain in place until a new round of testing yields results in the acceptable levels.