Lagoon water level still dropping

00:06, Apr 02 2014
COMPETITION: A canoe polo tournament in November last year, when water levels were higher. Jake Pain no.5 and no.7 is Ben Caldwell.

Organisers of a national canoe polo tournament in Palmerston North are pressing on with the event despite a continued dramatic loss of water from the Hokowhitu Lagoon.

The Palmerston North City Council said last month it suspected the water was draining through channels under the lagoon, opened up by the Eketahuna earthquake on January 20.

Council leisure assets manager Brian Way said yesterday that small stakes that engineers put in at the water's edge a week ago made it clear the water level was still dropping. "By six days later the water's edge had moved a further metre away from those pegs, so it's still losing water even though it's got water going in."

An artesian bore was supplying water at a rate of 15 litres a second.

"The data showed that up until the earthquake it was quite variable, the amount that was going in, because it's on a float system - if the level of water in the lagoon is high then less is flowing in, and if it's low then more is flowing in.

"From the day of the earthquake it has flatlined at 15 litres a second. Quite dramatic, actually."


Evaporation was not to blame, as that would lower the water level in the lagoon by, at most, 6mm a day.

"On a hot day, the maximum you would expect to lose in Palmerston North from 5 hectares of surface area is 300,000 litres of water per day - 1mm per square metre is 1 litre."

However, an inflow of 15 litres a second meant the bore was supplying 1.3 million litres a day.

"It's putting in four times as much as could possibly evaporate."

He had asked a geologist and geotechnical engineer to provide a report on what was happening, possible solutions and related costs.

"I'm just awaiting their proposal at this stage," he said.

There were fears last month that the A-grade national canoe polo league being hosted at the lagoon on April 12 and 13 would be scuppered because it was becoming too shallow to paddle.

Paddle Blacks captain and national competition chairman James Mitchell said he had contacted the city council yesterday to propose the canoe polo courts be shifted temporarily to the area on the other side of the Fitzherbert bridge, opposite the Kiwi Canoe Polo clubhouse.

"I did a survey last night with some other club members, and there's some really good deep water there," he said. Moving the courts there for two weeks would allow the championships and New Zealand men's training camp to go ahead.

Manawatu Standard