MENDOCINO CO., 8/28/2026 — A regional water quality control board has issued a health advisory for several North Coast rivers where toxic algal mats that can make people and animals sick have been found.
The North Coast Regional Water Quality Control Board — a state agency responsible for protecting water quality in the region — cautions people to keep themselves and their animals away from toxic algal mats in North Coast rivers such as the Klamath, Trinity, Salmon, Scott, Mad, Eel, South Fork Eel, Van Duzen, Navarro, Russian and East Fork Russian.
The agency urges people to pay special attention to keeping children and pets away from contact with algae or suspect river water since the toxic algae poses the strongest health risk to them.
The agency also advises North Coast river visitors to wash people and pets with clean water following contact with any river water and practice other healthy water habits such as properly cleaning caught fish and not using the water for cooking.
If signs of illness develop in people or animals after potential contact with toxic algae, state water board officials encourage people to immediately contact their healthcare provider or a local veterinarian.
Though the algal mats grow below the rivers’ surfaces on their riverbeds, state water board officials say the mats can break loose and float at the water’s surface along the shoreline, which can increase its probability of contact with people and animals.
The North Coast water board is working with regional partners to post signs alerting people of the toxic algal mats at locations where they have been found. The algae-infested locations can also be viewed online here.
However, state water board officials say that they encourage river-goers to keep their eyes peeled for algae — which typically ranges in color from dark green to brown or black — in areas without posted signs because algae conditions can change rapidly.
The board also advises people to continue to use caution at other North Coast bodies of water with preexisting algae advisories, such as Lewiston, Trinity, Ruth, Mendocino and Pillsbury lakes and Big and Stone lagoons.
