The allocation of new water from the Heretaunga aquifer could be coming to an end, the Hawke's Bay Regional Council has warned.
New scientific advice from the council has indicated the volume of water being taken from the Heretaunga aquifer is at its "maximum acceptable level", with all takes having an effect on surface water bodies.
This means granting new consents for further water allocation is "no longer acceptable".
Council chairman Rex Graham said at the height of summer, people were collectively pulling more water out of the aquifer than its streams and rivers could cope with.
"What we are saying now is that the evidence demonstrates we should not allow increased volumes to be taken from groundwater, let alone issue new water consents from the Heretaunga aquifer," he said.
"We are all in this together no matter where we are on the Heretaunga plains.
"Everyone on the [plains] has an impact on the aquifer."
Previous modelling done by the council has shown the aquifer is 460sq km in size, and 300m deep in some places. There are 1687 resources consents to take this water, and the total groundwater use is about 161 million cubic metres per year.
The council was satisfied that, at current usage levels, the groundwater was not being used unsustainably, he said, because there was still more water entering the aquifer every year than is taken for use.
However - the current volumes being taken out were having a significant effect on the Ngaruroro River, spring-fed streams, and a detrimental effect on in-stream ecology.
"It's not a situation where we need to panic, it's a situation where we need to be proactive.
"It's not a panic situation, we're not taking peoples consents off them ... we're just saying until we find out a lot more about this, we will not be issuing any new consents."
Council staff would be recommending any new consents for groundwater takes be declined, unless it could be shown they would not have adverse effects on surface water bodies.
Mr Graham did not think this would affect those with existing consents, as typically, people did not use the entire amount of water their consent allowed.
When asked whether restricting new consents might affect growth in Hawke's Bay industry, he said "it could but I doubt it".
"I think most [primary sector users] on the Heretaunga plains have wells already and have existing consents, there's not many people that don't. It won't affect consents in the pipeline, it's just from now on."
There were options for future water allocation being explored by the TANK Group - from augmenting stream flows, through greater water-use efficiency, or through a storage scheme.
The TANK Group is reviewing the way land and water resources are managed in the Greater Heretaunga and Ahuriri area.
By law, the council still has to receive, and consider new consent applications.
"But we are giving notice that our internal science advice is that the environmental effects of further takes must be avoided, remedied or mitigated before we can allow any more allocations for water takes.
"We hope this signal will result in a halt to further consent applications until the new TANK water management framework has been established."
The TANK Group will soon be developing rules to manage existing takes to ensure environmental effects are appropriately managed or mitigated, and existing investment in water use is accounted for.
Mr Graham said it was important people did not try to "game the system" unfairly for other water users. They would be looking at recommending a mechanism to the TANK Group that allocated water in the future based on historic use prior to this winter.