Harmful algal blooms, or HABs, have made news statewide and throughout the nation with reports of dogs falling ill or even dying shortly after swimming in waters with suspected blooms, the State Water Board said in a press release.

After performing testing on nearly 60 state waterways with a history of harmful algal blooms, the State Water Board last week put out a “danger” advisory for Iron Gate Reservoir and Copco Reservoir.

Harmful algal blooms, or HABs, have made news statewide and throughout the nation with reports of dogs falling ill or even dying shortly after swimming in waters with suspected blooms, the State Water Board said in a press release.

The Klamath River downstream from Iron Gate was put under a “caution” advisory, while the Klamath above Copco has been given a green “no advisory” designation.

Best identified by its blue-green, streaky appearance in water but sometimes not readily detected visually, HABs can be a danger to humans and animals, according to the release. Cyanotoxins in the algal blooms can trigger a range of health concerns, including irritation to the respiratory system, as well as skin, nose, eye, and throat discomfort.

Dogs and children are most vulnerable, as they tend to spend more time playing in the water and are more likely to swallow it.

Last week, the water boards gathered testing samples at many of the state’s most visited lakes and streams with a history of HABs, part of an annual collaborative effort with state and local agencies to gather data and share it with the public.

In 2018, 190 reports of potential blooms were received, and state and local agencies posted approximately 145 public health alerts at waterbodies throughout California, according to the press release. The interagency HAB-related Illness Working Group received 44 reports of potential HAB-related human and animal illnesses in 2018. Following further evaluation of the available environmental and health related information, the California Department of Public Health reported 19 cases to the Centers for Disease Control’s One Health Harmful Algal Bloom System as suspected, probable, or confirmed link to HAB exposure. These reported cases included eight human, four domestic animal, and seven fish or wildlife incidents.

The water boards, the California Department of Fish and Wildlife, Office of Environmental Health Hazard Assessment, and California Department of Public Health, along with water managers and county and state health officials, have teamed up to investigate reported cases of health impacts linked to freshwater blooms.

The results of the targeted sampling for about 40 waterbodies are summarized in an interactive map showing which sites were tested at each waterbody. The map also indicates the specific public advisory level – Caution, Warning or Danger –based on cyanotoxin testing results and/or visual indicators confirming the presence of a HAB. The map can be found here: https://mywaterquality.ca.gov/habs/data_viewer/

Red and orange dots indicate waterbodies with limited water recreation (i.e., no swimming) due to elevated levels of cyanotoxins, though it is important to understand that HAB location and toxicity can change quickly and, as a result, the data in the map is subject to revisions as new information becomes available.

“While harmful algal blooms may be a new health hazard to many in the general public, algae and cyanobacteria have existed for billions of years as essential components of freshwater ecosystems,” the release states. “Only when certain conditions trigger their growth – hot weather, slow-moving or stagnant water and excessive nutrient input – do they multiple rapidly and become a health threat.”

The release states that it is important to distinguish cyanobacteria/HABs from green algae and other non-toxic water plants. HABs can be a variety of colors such as green, white, red or brown and may look like thick paint floating on the water. Cyanobacteria blooms have a grainy, sawdust-like appearance of individual colonies, according to the release.