The Department of Environment and local veterinarians are pointing to blue-green algae as one of the most likely causes of contamination at Grand Lake, N.S., that led to the death of two dogs and one person being hospitalized this week. An alert was issued early Thursday morning warning all residents who take water directly from Grand Lake to stop using the water immediately. Residents near Grand Lake who don't receive water from a municipal utility are advised not to consume their water, or use it for cooking, bathing, swimming or boating, until told otherwise.