Warning over waterway pests

SOUTHERNERS wading into waterways are being urged to clean equipment this summer to avoid spreading freshwater pests.

The Otago Regional Council and Ministry of Primary Industries are reminding those living in or visiting Otago and the Southern Lakes of the importance of cleaning equipment between waterways to avoid spreading pests including invasive algae didymo.

Freshwater pests such as didymo, lake snow and hornwort posed a serious threat to rivers, streams and lakes, it said.

Council acting environmental monitoring and operations director Peter Winder said once they were in a waterway, they could disperse rapidly and destroy environmental, recreational and aesthetic values.

‘‘We ask people going between waterways to check, clean, dry any equipment that has come into contact with river or lake water.

‘‘Some freshwater pests, like didymo, are microscopic and can be spread by a single drop of water. Even if you can’t see the danger, you could be spreading it.’’

Before leaving a waterway, people should check their items for any weeds or debris and leave it at the waterway they found it in, he said.

All items including swimsuits, fishing lines, jandals, boats and anything else that has made contact with water should be cleaned for at least one minute with a 5% solution of biodegradable dish washing solution, or about one tablespoon of detergent per 250ml.

Waterabsorbent materials such as lifejackets, wetsuits and boots require longer soaking times.

Drying will kill didymo, but even slightly moist items can harbour didymo and other microscopic pests.

To ensure didymo cells are dead, the item must be completely dry to the touch inside and then left to dry for at least another 48 hours before use.