People and pets should stay out of the water behind Little Goose Dam because of a bloom of toxin-producing algae, according to the Columbia County Health Department.
In addition, fish caught behind the dam on the Snake River near Starbuck should not be eaten, according to the health department.
The algae is producing high levels of the toxin microcystin, which can be harmful to people or animals who come in contact with it, drink it or eat fish with toxin buildups.
Warning signs are posted at the dam, boat launch and along the south shore of the lake. Tests will be done weekly until the algae toxin levels have dropped to levels considered safe.
The microcycstin toxins can cause breathing problems, stomach upset, rashes and, in large amounts, liver damage.