An ugly algae bloom called lake snow is biting Queenstown Bay boaties, and even stopped the iconic Earnslaw tourist steamer in her tracks.
TSS Earnslaw chief engineer Peter Dorrington calls it “horrendous” and says it surfaced “almost overnight”.
“We found it in the generator cooling water filters in early January,” he says.
“It basically stopped one of our sailings because the generator stopped working so there was no power on board the vessel.
“They’re the same filters we’ve been using for the last 20 years – we used to clean them every couple of months, now we have to clean them daily.”
Phil Novis, who’s leading the lake snow toolbox project for Manaaki Whenua-Landcare Research, confirms “we haven’t found anything that can be done to eliminate or at least mitigate its effects”.
However, data will be collected during the 2019/20 season which “may shed light on the cause of lake snow”.
“When the cause is known, the feasibility of various solutions can more easily be evaluated.”
Novis adds that the problem’s worse in Lake Wanaka than lakes Wakatipu and Hawea.
It’s a pest that veteran fishing guide Stu Dever is reeling in on every line cast from his boat.
“Chinese [visitors] have actually said to me, ‘gee, this is pretty bad, it’s worse than it is in China’,” he says.
Dever says the problem’s got progressively worse over the past few years.
He struck lake snow for the first 328 days last year before getting some respite, but says it’s back now.
“It clogs up the lines and it looks really, really ugly, it’s really thick.
“It’s a shocker, really.”
While stressing you can still catch fish, it can ruin the experience.
Dever says lake snow starts off small, then coagulates.
“As it gets bigger, it starts descending.
“It might start at, say, 10 metres, then it goes down to, say, 20m, then 30m, then 40m, then it might just disappear so it must go to the bottom.”
It’s thought local lake snow can be traced back to Lake Youngs in Washington State in the United States.
Dever says he’s not aware there’s a solution to the problem.
“You can’t just empty the lake and start again.”
Queenstown Paraflights director Quinn Wilson adds: “It blocks the water pick-up filters so you’ve got to clean them out every day.”
Mountain Scene’s previously reported that the algae has also affected Queenstown’s water supply, in particular clogging up some accommodation providers’ water filters.