Environment Southland's latest assessments have found Elevated levels of toxic algae in the Waiau River near the Excelsior Creek inflow. The algae can be harmful to people and animals if swallowed, or through contact with skin. People and animals –dogs in particular – should avoid contact with the water until health warnings are removed. For more information and to see our frequently asked questions on toxic algae, go to www.es.govt.nz/toxic-algae.