The Wairarapa Waka Ama Canoe Club says it has been "set back" because of the toxic algae in Henley Lake, describing this year's bloom as the worst it has seen.
Club coach Paddy Rimene said, in the nine years he has been training on the lake, he has never seen the algae so thick, "especially around the edges".
"Every year it's the same story, but I've never seen it as bad as it's been this year."
Mr Rimene has been running the Wairarapa Waka Ama Canoe Club for four years, and each summer, due to algal bloom in the lake, "the club just shuts down".
"It's been a bit of a shame for the club because this is the prime time to train," he said.
"It's a big setback because it stops us from taking young children to the secondary school nationals because you just can't get in the water."
He said the children could still train on land, but "you've got to be on the water if you want to be competitive".
Mr Rimene trains at the Whareama River when the lake is unusable, but he said it was too problematic to take his club members there.
"It's too hard logistically to take the kids and the canoes to keep training.
"It's only a 35-minute drive but there and back it's over an hour for travel and, if you get the tide wrong, the water is quite shallow and if it's windy it's a bad place to be."
Mr Rimene said Henley Lake was a great venue for training, saying "you can't really ask for more".
"When it's windy, it's still flat and it's a perfect training ground if you're coaching because you are right next to the shoreline.
"It's not the deepest but when you deal with kids, the youngest being five, that's a bonus, at most they're only probably 20 metres away from the shoreline."
He said it was an issue out of everyone's control "because you can't control the weather".
With temperatures starting to cool down, Mr Rimene hopes to have his club back on the lake soon.
The Cancer Society Wairarapa champion dragonboat crews are hoping the same as well, as their season gets under way.
CSW chairwoman Kay Wilton told the Times Age on Sunday that their performance had "suffered" due to not being able to use the lake for training for six weeks.
The team came second in the women's grand final in the Wellington Dragonboat Festival on Saturday.
Masterton District Council spokesman Sam Rossiter-Stead said the hot, dry summer and low flows in the Ruamahanga River had been "perfect conditions" for growing algal bloom.
He said flow restrictions on the Ruamahanga River had prevented any new water from entering Henley Lake, allowing its water temperature to rise.
"The flow restrictions are in place to ensure that water is only taken from the river when it's above a certain level, so that sufficient water remains in the river for the fish and other aquatic life that rely on it."
Mr Rossiter-Stead said the bloom in the lake in 2016 had been no worse than previous years.
"The lake closed for recreational water activities seven weeks ago, which is a relatively short period of time so far.
"In 2013, for example, it was closed for 17 weeks until mid-May."
He said the growth of algal bloom in recreational lakes was something that affected bodies of water in many places around New Zealand.
"Henley Lake is wholly reliant on the Ruamahanga River to flush it through, keep the water moving and keep it cool.
"Following considerable research, there is no cost-effective or environmentally appropriate solution to this annual issue that we are aware of.
"History shows us, once average water levels return to the Ruamahanga River and the air temperature begins to fall, the problem clears up relatively quickly as the bloom die away."
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