Dry rural land in the Bay of Plenty. Photo / Andrew Warner
There is enough water to sustain the city's normal winter use despite water restrictions remaining in place in Tauranga for longer than normal, according to the Tauranga City Council.
Stephen Burton, council director of city waters, said yesterday that due to "unprecedented dry conditions," stream flow rates that supplied the city's drinking water were down.
"Stream flows are at an all-time low, which we attribute to the very low rainfall over the past two years, estimated to be more than 30 per cent below the average rainfall."
A sprinkler and irrigation system ban was still in place for Tauranga and was necessary to manage water usage and ensure there was enough to sustain regular winter demands.
In the interim, the council was looking at opportunities for water sources to support existing supplies, but none of these would be quick fixes, Burton said.
"We are focused on bringing the next water supply scheme, Waiāri, online by late 2022. This scheme would significantly improve the city's water supply."
The Bay of Plenty Regional Council said the region had experienced three consecutive dry summers, and a lower than average rainfall in winter and spring.
Steve Pickles, water shortage event manager and regulatory compliance specialist, said this rainfall deficit paired with warm, dry conditions had caused a reduction of water flowing into the region's streams and springs.
"[This] is the likely cause of the lower stream flows being experienced in Tauranga City Council's water supply streams."
The Western Bay of Plenty District Council said their council's water supply is from bore fields rather than streams like the Tauranga City Council's supply. It was therefore not subject to the same problems caused by dry weather spells.
"Currently this is a bigger problem for Tauranga City Council," said the council's infrastructure engineer of water, Paul van den Berg.
"Western Bay of Plenty District Council is currently focusing on exploring new underground water sources to develop bores in the district to meet increases in demand due to growth in our district."
President of Federated Farmers Bay of Plenty, Darryl Jensen, experienced the consequences of lower rainfall on his farm, with a water source he has used since 1958 having "virtually run dry".
"That's because of the shallow wells or bores – the water is not there anymore because of our consecutive dry summers. Those water levels have not charged up.
"There is certainly this pressure on the water resources we've got. The Western Bay is going through a huge growth phase at the moment, and where there's growth there is an increasing demand on water.
"Councils and farmers need to look at the big picture and think long-term. We need to be smarter about how we're using our water."
Te Puke farmer Rick Powdrell had not encountered problems from reduced rainfall on his farm because he had a good bore system, but knew of people who had.
"It has been an issue for a number of farmers. A lot of people down in the lower country have had wells drying up.
"Industry and population growth uses a lot of water. Extensive kiwifruit and avocado development – all those things are putting more pressure on supplies of water."
Chris Brandolino, meteorologist at the National Institute of Water and Atmospheric Research, said that from a climate change perspective, events of reduced rainfall would only become more extreme.
Brandolino explained the ground is like a sponge, which needs to be saturated to release excess water. Due to extended periods of reduced rainfall between January and May 2021, this has meant the ground is dry and not releasing water into rivers and streams.
"There needs to be sustained rainfall for several months for the ground to be sufficiently wet. But it will take a long time for the improvements to trickle down into the rivers and streams because they are last to respond."
He said now was a critical time of year for water supplies to recharge.
"[Between] mid-autumn and early spring is the time where we want to replenish the soil, streams and rivers. In October it is warmer, we get stronger sun, and that strips moisture from the ground."