Sonoma County health officials are warning people to be careful after blue-green algae was found near a beach in the lower Russian River. The algae, also known as cyanobacterium, was found in the water off Patterson Point in Villa Grande on Thursday. The North Coast Regional Water Quality Board has taken samples, but has not yet released test results, so we don’t know if the algae is toxic. People are advised to prevent their children and pets from touching and drinking water when blue-green algae is present. On Wednesday, another bloom of blue-green algae was discovered near the Howarth Park boathouse at Lake Ralphine, preventing boat rentals from docking.