Some of the decisions and engineering behind Nelson’s Maitai Dam hit the headlines earlier this year when a 12 metre section of the main pipeline was destroyed by a slip during the August storm event.
The pipeline was successfully repaired three months later thanks to innovative engineering solutions, but the dam itself, which turned 35-years-old earlier this year, and some of the people behind it, also deserve some recognition.
Costing $9.7 million in 1987 (over $20 million today with inflation), the “state-of-the-art” dam took three years to build, but the discussions first started back in the 1930s.
At that time, the government funded the Roding Dam as this supplied water beyond Nelson to Richmond Borough and Waimea County council areas. In the 1950s the council of the day looked at the Maitai River again, and despite the pipeline part of the scheme being constructed in 1963, the dam was postponed due to financial concerns.
However, by the 1970s the town supply was at risk of contamination and running out in dry spells, so the debate ignited once again.
Former deputy mayor Seddon Marshall, a councillor of 33 years (1968 to 2001) was very much in the thick of things.
“We had some pretty irate people,” he says. People were concerned about environmental issues, water flows, costs, biodiversity, earthquakes and the dam bursting.
Despite this, he says that the severe water restrictions in the 1960s, whereby truckloads of galvanised watering cans needed to be transported to the city for watering gardens, were still front of mind for many people. A feasibility study was commissioned in 1981, and despite some vocal concerns he says that “the community as a whole appreciated the need for the dam.”
And in 1984 the council gave the go-ahead for the dam ... but not after many reports and even more fierce debates!
Former councillor Kerry Neal says that one of the big debates centred around the location of the dam.
“Originally it was meant to be downstream of the Forks, taking in both the South and North branches. So the current location was a compromise to ensure that the Southern branch remained untouched” as it was considered an important spawning and rearing area for trout.
Unfortunately, Seddon says, it “became a lot more complex” due to that decision.
Works Engineer David Faulkner finalised the designs for the new Maitai Water Supply Scheme in 1984 – a 36-metre-high earth-fill dam with the capacity to hold four million cubic metres of water that spans 32 hectares.
And with the mayor out of town, Seddon was given the unenviable task of signing the 600-page contract.
“I had to read and initial every single page,” he says.
Under the careful oversight of the Chair of Works committee Ian Gourdie, construction started later that year and the work was completed in 1987.
“Ian was a great strategist and a great guy as a councillor,” says Kerry. “It wasn’t a simple task, but he had the unique ability to be able to take stress and overcome obstacles.”
And while the Maitai Dam holds lots of water, it isn’t the source of the city’s water supply. Instead, the dam was designed to hold water that could be released at times of need to maintain the flows in the river, but is still there as a back-up in times of peak summer demand.
