Water from the pond then entered into the aquifer and flowed across to Bore 1 where it was pumped into the reticulation, Mr Stevens said.
The inquiry found that several parties with responsibility for supplying water for Havelock North, in particular the Hastings District Council (HDC), Hawke's Bay Regional Council (HBRC) and Drinking Water Assessors (DWAs) failed in their duty to protect public health and prevent such outbreaks, and that a higher standard of care needed to be embraced.
The failings, most notably by the regional council and the district council, did not directly cause the outbreak, although a different outcome may have occurred in their absence.
"August's outbreak was not Havelock North's first experience of drinking water contamination and lessons that should have been learned from an earlier contamination had been forgotten," Mr Stevens said.
He was referring to an outbreak of campylobacteriosis in July 1998 in two Brookvale Rd bores, the same location as last year's event.
A report done at that time raised doubts about the confined status of the Te Mata aquifer beneath the bores and recommended testing the aquifer as well as introducing measures to ensure the security of both boreheads.
"Regrettably, while the two outbreaks share remarkable similarities, it appears nothing was learned from the July 1998 outbreak."
He also listed other failings on the part of the Hastings District Council, including the actions of its mid-level managers who delegated tasks but did not adequately supervise and ensure their implementation.
"This caused unacceptable delays to the preparation of a Water Safety Plan, which was fundamental in addressing the risks of an outbreak of this nature."
In addition the HDC failed to properly manage the maintenance of plant equipment or keep records of that work, and it carried out little supervision of necessary follow-up work.
Contingency planning was also lacking on the part of the HDC - such as draft boil water notices or communications plans at the ready.
Consultancy firm MWH New Zealand Ltd, a technical adviser to the district council, was also criticised for failing to competently assess and report on the security of the Brookvale 1 and 2 boreheads.
The HBRC did not escape censure, including what was called its "dysfunctional" relationship with the Hastings District Council.
"That strained relationship together with an absence of regular co-operation saw a number of missed opportunities that may have prevented the outbreak," Mr Stevens said.
He said the HBRC failings included it not meeting its responsibilities under the Resource Management Act to protect the Te Mata aquifer, which was the first and most critical step in a multi-barrier approach to ensuring safe drinking water.
He said the council's knowledge and awareness of the aquifer and the risks fell below the required standards, including knowledge of the state of numerous uncapped or disused bores in the area.
The inquiry found the regional council also failed to monitor compliance with the conditions of permits granted to Hastings District Council to use the bores.
The DWA's also came under the spotlight in the report for being too "hands-off" in applying the drinking water standards.
They should have been stricter in ensuring the HDC complied with its responsibilities, such as having an Emergency Response plan, and they failed to press the HDC sufficiently about the lack of risk assessment, analysis of key aquifer catchment risks and a meaningful relationship between the HDC and the HBRC.
Aside from these factors, the inquiry found all parties had generally handled the outbreak well, particularly the Hawke's Bay District Health Board.
None of the faults, omissions or breach of standards directly caused the campylobacter outbreak but they did contribute, Mr Stevens said.
"It's been accepted by those responsible for the failings that greater diligence and co-operation is needed for a higher standard of care and it needs to be in place soon."
Since the outbreak the Hastings and Havelock North water supplies have been chlorinated, including at Brookvale Bore 3 which was re-commissioned to augment water supply to the village during the summer months.
Mr Stevens said this Stage 1 report did not contain any recommendations, it was about ascertaining the relevant facts.
Stage 2, due to be reported back in November this year, would focus on lessons that could be learned and potential improvements for the future to prevent similar incidents happening again, he said.
The panel would take particular heed of information coming from the Joint Working Group that was set up last year, and would look at implications for other parts of New Zealand.
He said the inquiry would continue to monitor the Havelock North water supply despite the substantial improvements made when reactivating Brookvale Bore 3.
