The chairman of a regional council has hit out at his own council, saying it needs to "keep their nose out" of the lake he manages after it issued swim warnings due to high levels of algae.

Horizons Regional Council chairman Bruce Gordon said signs were keeping people away and Horizons "don't contribute anything except for putting out warnings that are doing a lot of damage".

But the council's water spokesman Barry Gilliland issued a warning saying the blue green algae density in the lake exceeded recreational guideline criteria again this week.

"Warning signage was posted last week and needs to remain so. It is best to stay away until this bloom burns itself out," his email said.

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And the children of Dudding Lake caretaker Quentin Salepau suffered a red, stinging rash that lasted two days after swimming in the lake three weeks ago before warning signs were put up.

But Gordon said the council's message was making people cancel their bookings.

He is both the operations manager for Dudding Lake Motor Camp and Picnic Park, near Marton, and the chairman of the regional council charged with maintaining and monitoring the water there.

Gordon saw no conflict of interest between his two roles.

Gilliland later clarified he meant to tell people to stay out of the water, not out of the whole reserve.

But the lake is the reserve's main drawcard, Salepau said, and the algal bloom is putting off campers.

"Ever since the notices have been up no one has been here except a jetboat. Last weekend it was dead."

It's been a struggle to keep the facility going and money from campers is needed. Gordon said messages from the council he chairs have been a problem.

"We would like Horizons to keep their nose out of the place, to be quite honest. They don't contribute anything except for putting out warnings that are doing a lot of damage."

Horizons had assumed responsibility without being asked, he said, and didn't monitor other coastal lakes as closely.

"They stick their nose in sometimes where they're not wanted."

Horizons chairman Bruce Gordon sees no conflict in his role as operations manager for Dudding Lake Motor Camp and Picnic Park. Photo / File
Horizons chairman Bruce Gordon sees no conflict in his role as operations manager for Dudding Lake Motor Camp and Picnic Park. Photo / File

It's too cold to swim at the moment and waterskiers in wetsuits will not be harmed by the algae, he said.

People just needed to avoid their skin contacting the shallow water around the lake edge.

Dudding Lake near Marton is experiencing a pre-Christmas algal bloom. Photo / Stuart Munro
Dudding Lake near Marton is experiencing a pre-Christmas algal bloom. Photo / Stuart Munro

Yesterday Horizons staff were testing the water again.

A close look showed it was full of tiny particles.

Gordon said the lake often has algal blooms early in the season, which die down later.

Algal blooms happen when water is warm and has plenty nutrients - such as nitrogen and phosphorous from farming run-off - to feed the algae.

Dudding Lake has farmland, including some crops, on one side, and forestry on the other.

It is Horizons' job to set rules that limit nutrient run-off, and last year two environmental groups took it to court for failing to regulate. It lost the case.

The council is now seeking to change the maximum nitrogen leaching figures allowed by its One Plan.

Dudding Lake has a few freshwater mussels (kakahi), and more may be added to filter the water.

Gordon said nonbreeding carp could also be introduced, to eat lake weed, and stock still have access at times when the water is high.

He doesn't doubt the results Horizons scientists come up with, but says Rangitīkei District Council's Blair Jamieson has better solutions to the algae problem.

"I'm going to tell Michael [McCartney, Horizons' CEO], let's just let Rangitīkei do it."