Clutha District Council (CDC) is warning pet owners to be vigilant along the district's waterways after the death of a dog which drank water by the riverside.
Toxic algae blooms often form in waterways in the area at this time of year and it can be deadly to dogs.
While Otago Regional Council monitors swimming spots, algal blooms are a risk anywhere along rivers. Warm conditions also provide ideal conditions for potentially toxic algae or bacteria.
CDC service delivery group manager Jules Witt said they were aware of a local dog which had died after drinking water by the river side.
CDC said dogs needed to be kept on a lead near waterways and well clear of washed-up mats of algae or stagnant water on the riverside.
Any person - or dog - who may have had contact with toxic algae, should rinse off with fresh water as soon as possible.
Anyone experiencing a reaction from contact with it should seek urgent medical attention, and any signs a dog has been poisoned (lethargy, muscle tremors, fast breathing, twitching, paralysis and convulsion) should be treated as an emergency and referred to a vet immediately.