MONTANA — State health officials warned people heading to the water this weekend to watch for harmful algal blooms reported across Montana during the past week.

Officials said some of the blooms could produce toxins that were dangerous to people and pets. They reported new blooms at Canyon Ferry Lake, Cooney Reservoir, Hebgen Lake, Tongue River Reservoir, Hauser Reservoir and Elk Grove Pond.

Officials described harmful algal blooms as blue, green or gold. They said the blooms could look like pea soup, grass clippings or spilled paint.

They also explained that hot weather, strong sunshine, slow-moving water and other environmental conditions had helped fuel the blooms.

"When in doubt, stay out," officials said.