Fish-friendly pump installed
Milestone towards safe passage to sea
Anew fish-friendly screw pump near Waiuku is helping fish get safely to sea for spawning. The Archimedes screw pump, installed by the Waikato Regional Council in Aka Aka, north Waikato, marks a massive milestone towards managing fish passage in New Zealand waterways as required by the National Policy Statement for Freshwater 2020.
Pathways to the Sea Project manager Michelle White says the installation of the pump at the Mangawhero pump station “is the start of our mission to provide native fish with safe passage to the sea for spawning”.
When the regional council recently tested the new pump, tuna (eels) were seen going through the enclosed screw pump and pump station outlet, making it to the other side safely.
The pump is 10m long and has a 1.6m diameter. It is the first of its kind in New Zealand and was built by Fishflow Innovation in the Netherlands. When it arrived last year, regional council project manager Richard Dodera described it as “an impressive piece of kit”.
“This pump will push out up to 520 litres per second during a flood and we expect it will provide safe passage for long and short-fin eels. It’s so big you could probably put a small shark through one if we had them in our catchments.”
White says the council will test the
enclosed Archimedes to see how successfully it passes New Zealand native fish species as part of its research into minimising fish mortality through pump stations.
In Europe, enclosed Archimedes screw pumps have proven to be 100
per cent fish friendly.
“We’ll be looking at whether tuna avoid the pump, what size tuna are passing through and assessing to see if there is any injury or mortality as a result of tuna passing through.”
The monitoring will take place during the 2023 migration season.
The council’s Integrated Catchment Management chairman, north councillor Stu Husband, says the pump has benefits other than safe fish passage.
“It operates to support drainage in the catchment, and to transfer water during high rainfall events,” he says.
“It rotates very slowly and delivers high efficiency so is cheaper to run, and it’s a simple design that won’t require much maintenance.”
An enclosed Archimedes screw pump will also be installed at Churchill East pump station, near Te Kauwhata.
Waikato Regional Council received $4.48 million from the government’s regional economic development unit, Kanoa, to help upgrade up to five pump stations in the Waikato to enable safe fish passage. Other sites are still being assessed for suitability.
A blessing will be held at the Mangawhero pump station in the coming weeks, the council says.
The regional council has about 182 pump stations in the Waikato, which help protect communities’ lives and livelihoods. It is developing a regional infrastructure fish passage strategy that will identify priority pumped catchments for fish passage and the appropriate measures to do so, such as fish-friendly pumps.
The council has also partnered with Macewans Pumping Systems to develop fish-friendly impellers for retrofitting older pumps.