Otago Regional Council is closely monitoring rivers and lakes in Otago for the invasive exotic algae Didymosphenia geminata, and urges people to take care not to spread it from one waterway to another.

"We are very concerned about the discovery of didymo in our region, and will work closely with other agencies such as Biosecurity New Zealand, Fish & Game and the Department of Conservation to help curb its spread," said Chairperson Stephen Cairns following the confirmation of the pest in the Hawea River and the Upper Clutha River this week.

"Since the pest was first found in New Zealand late last year, the Council has had staff surveying all the most likely sites, based on what's known about didymo. It's only this week that the first visible blooms have been identified in Otago.  We have also identified the waterways where we especially don't want the pest, such as our high country streams and rivers."

Cr Cairns said that the algae seemed to favour cold and clear shallow running water with stable flows and substrate.

Many South Island rivers are at high risk.  With the fishing season about to open tomorrow, we are relying on river users to take precautions so as not to spread the pest.

It's best not to move from one river to another. It's also critical that people remember to disinfect all their gear, with a solution of bleach, salt or detergent, every time they leave a waterway. Not just rod and reel but anything that's been in the water including footwear. Boat owners need to also take care, and wash down their boats and equipment prior to entering any new waterway.

Cr Cairns said people should report any suspicious suspected sightings of the algae in Otago to the Council on 0800 800 033 or Ministry of Agriculture and Fisheries on 0800 809 966.

Commonly known as 'rock snot', Didymosphenia geminata (Didymo) was found in Southland rivers in October 2004, and has also been confirmed this week in the upper reaches of the Buller River in the Tasman District.

By: Tamah