Hastings District Council has apologised after flood protection work caused dirty brown water to run from the taps of some of the hardest cyclone-hit communities in the region.

It is now immediately pressing go on a plan for a replacement water source for Esk Valley and Whirinaki which, when complete, will be double the size of an existing but deteriorating reservoir in nearby Pan Pac Forest.

The council had received about 50 calls in the past 12 months from 24 residents regarding water discolouration, with two-thirds linked to three significant discolouration events, a council spokesperson said. “We know discolouration has been an ongoing and frustrating issue for the community, and we are committed to keeping you informed.”

The spokesperson said discolouration issues were caused by elevated levels of manganese, a naturally occurring mineral.

“Contractors carried out a weekly flushing programme to reduce the build-up of manganese in the system. This should help prevent larger accumulations that can cause significant discolouration. The water treatment facility for this supply does not include treatment for the removal of manganese, as it wasn’t present in the supply at the time of construction.”

The spokesperson said council had first noticed higher levels of manganese in the source water after Cyclone Gabrielle, and they had continued to rise to a level that was now noticeable to residents.

The spokesperson said the new reservoir would improve the resilience of the water supply at Whirinaki and help meet demand during peak use periods.

The Haumoana and Te Awanga and Napier water supplies had all had similar issues in the past until a new source was established.

The old reservoir was now offline and demolition was under way, with the new reservoir expected to be operational by mid-2026.

The council was also looking at an even longer-term solution. This included a connection to Napier’s municipal water supply or a new water source and treatment plan. The spokesperson said its preferred option was a connection to Napier’s water supply. Modelling is under way using a recently developed water supply model to determine whether the Napier network can provide enough pressure and flow to service the Whirinaki and Esk Valley communities.

The second option involves developing a new water source and drilling a new bore or bores to supply a new treatment plant outside the flood hazard zone, connected to the existing reticulation network.

The council was working with a landowner and, subject to final agreements, planned to proceed with investigative drilling in March. Parallel, modelling is underway to assess the impacts of supplying the network from this location.

Funding for the project has been approved through council’s Long-Term Plan.

Temporary water storage has been installed to ensure a continued water supply while the reservoir is being replaced. This is expected to be finished by mid-2026.

LDR is local body journalism co-funded by RNZ and NZ On Air.