Nova Scotia's Department of Environment is investigating a suspected blue-green algae bloom in Grand Lake, north of Fall River, after two dogs died and one person was sent to hospital Wednesday. The province issued an emergency alert early Thursday morning, warning all residents who take water directly from Grand Lake to stop using the water immediately. "What we do know is there's obviously a toxin," Julie Towers, the department's deputy minister, said Thursday afternoon. "Whether it's human-caused or a natural source is to be determined."