The warning was issued on June 22 after the state collected water samples at the head of the Ossipee River dam. Cyanobacteria are natural components of water bodies worldwide, but blooms and surface scums may form when excess nutrients are available to the water. Potential acute health effects include irritation of skin and mucous membranes, tingling, numbness, nausea, vomiting, seizures and diarrhea. No further blooms have been observed in this area at this time, according to the state.