Work on identifying the source of the odour problem in Waipukurau, and efforts to resolve it, are now well under way after complaints from residents about the smell that has strengthened in recent weeks.
The Hawke's Bay Regional Council confirmed on Thursday that it had received 43 calls to its pollution hotline since December last year, peaking in the last six weeks with 13 calls in May and 16 this month so far.
The CHB District Council informally discussed the matter last week in order to get an update on the problem that is centred around the Waipukurau wastewater treatment plant's anaerobic pond, but had also been experienced on the other side of town, as far as Thornton Lodge Motel on Takapau Rd.
Councillors Gerard Minehan, who lives on the same road as the treatment plant, and Shelley Burne-Field said they had received multiple calls from residents over the last week, complaining about the issue and asking what was causing it.
Mr Minehan said he had experienced the sulphuric smell that "goes down your throat".
"This situation is like a pressure cooker and we need to get on to it."
Asked to give an update, chief executive Monique Davidson said feedback had indicated the problem was widespread, and cautioned it was still not entirely certain the pond was the only source.
"There are some strange things happening, and there could be a lot of things contributing, so we have to keep an open mind about that."
In the meantime, work on covering the outlet structure of the pond was already under way, and a sleeve for the pipe outlet was currently being manufactured, due to be installed by the end of the week.
Contractors were also gathering CCTV footage inside the piping network to check that everything was in order, and investigations to source a suitable flare to burn off the gas from the pond were ongoing.
Mrs Davidson again acknowledged that council communications up until this week had not been at the "level of excellence" the council strived for and said council staff were dropping leaflets off with residents and businesses to explain the situation.
In addition, an online survey had been created asking people for information as to when and where, and in what conditions the odour was experienced.
Councillors also discussed holding a public meeting, as there had been talk that residents themselves were thinking of such action.
"My advice is we wait to test whether the actions we have under way make a difference and further isolate the issue," Mrs Davidson said.
"If this continues over the next two weeks we may need to consider a public meeting."
CHB mayor Alex Walker said the message from the community was that the problem needed to be resolved, and noted the dedication of all council staff involved in trying to identify and fix the issue.