Southland water enthusiasts are urged to be vigilant about keeping their equipment clean, in an effort to prevent freshwater pests, like lake snow from spreading to more of the region’s waterways.
Recent samples from one of Meridian’s Manapouri Power Station cooling water units tested positive for the slimy algae, which is already present in a number of lakes around the country including Lakes Wanaka, Wakatipu and Hawea.
Environment Southland senior biosecurity officer Randall Milne said council monitoring has been carried out in Te Anau and so far hasn’t picked up the presence of lake snow, but it’s likely to be present.
The origins of the lake snow are unknown, however research suggests it is a recent introduction to New Zealand, with no evidence to suggest that it was present before 2001.
“At this stage there is no silver bullet for getting rid of lake snow,” Randall said.
Although lake snow is not toxic and poses no known human health risk, it is creating costly problems for water users. If it gets into the residential water supply, lake snow causes blockages, clogs filters and household appliances connected to the system.
On the lake, fishermen may find the algae accumulates on their fishing lines and lures. It can also stick to boat hulls and equipment, wetsuits and your skin or hair if you come in contact with it.
“It’s important that we protect our waterways from all freshwater pests by being very careful when moving from one waterway to another. People need to follow the Check, Clean, Dry actions for all boats and equipment being transferred from one area to another, to ensure they are not carrying anything unwanted.”
What is lake snow?
Lake snow is a sticky, biological material made up of diatoms – these are single cells of algae that form colonies. Lindavia intermedia are the algae species responsible for creating lake snow.
The lake snow algae secretes large amounts of polysaccharide, a glue-like substance, which cause the algae cells and other microscopic organisms to clump together on the water surface.
When present in high quantities, frothy white flocs appear on the surface, giving rise to its snow-like appearance.