Pressure on the use of the controversial hydraulic fracturing, or 'fracking',to extract gas from underground, is growing as the technique and its environmental implications come under increasing scrutiny.
Regional and district councils have taken stances for and against, the Parliamentary Commissioner for the Environment (PCE) is investigating, political parties are at loggerheads, and community protest groups are springing up to stand alongside hardened activists such as Greenpeace.
Like it or not, it could be the councils who will have to make the inaugural front-line decisions on whether fracking can take place in their patches.
That scenario could change, however, as a result of the PCE's investigation, which could recommend a moratorium on the technique until more is known. What is incensing environmentalists and raising alarm in communities about fracking is the potential for toxic fluids, which make up about 3 per cent of the high pressure injection fluids, contaminating water aquifers.
The Government wants to increase New Zealand's oil and gas exploration by 50 per cent and has decided not to impose a moratorium on fracking, instead waiting for the PCE's report.
France, Quebec, New South Wales and the European Union have moratoriums in place, and earlier this month the Christchurch City Council unanimously voted to impose the first moratorium in New Zealand.
With 17 oil basins, ranging from the relatively low-investment-risk Taranaki to the high risk of the deep-water Great South Basin, the Government is targeting an annual sector-value increase from $3 billion to $12 billion a year.
Fracking has been used successfully dozens of times in Taranaki in recent decades, Apache Corporation is considering using it on the East Coast, and though it is understood to have never been used in the South Island, listed oil and coal seam gas explorer L&M Energy has shown interest in southern "shale" oil deposits, under its "unconventional" prospects guidelines.
Shale, a clay-based rock, has natural gas and oil trapped in it, but this can flow if the rock is fissured and high pressure liquids displace them, pushing hydrocarbons to the surface through the well casing.
In mid-February, before the Christchurch Council's moratorium, the Taranaki Regional Council released its risk assessment on fracking, based on data over 18 years from 60 fracking events at 33 oil and gas wells up to 4km deep but at an average 2.4km.
The report said that "If hydraulic fracturing operations are carried out properly, it is unlikely that contaminants will reach overlying freshwater aquifers in the Taranaki region. However, although unlikely it is not impossible."
The report said fracking at "relatively shallow depths" under aquifers, which generally lie no deeper than 1000m, did pose a greater level of risk, and it called for a "more stringent regulatory oversight".
Leakage of fracking contaminants to the surface would have to pass through "hundreds to thousands of metres in most cases" of low permeability "geological seals"; natural barriers to hydrocarbon leakage, the report said.
Energy and Resources Minister Phil Heatley told TVNZ recently he had "no concerns" over fracking, given the "reality" that it had been happening in Taranaki for 20 years with no incidences of water quality issues or earthquakes.
"In New Zealand, where it's practised very deeply in the earth, well away from aquifers, it appears to be safe.
"The Parliamentary Commissioner will have the last word," Heatley said on Q&A.
Green Party mining spokesman Gareth Hughes is calling for a moratorium until the commissioner's report is released, probably toward the end of the year.
"Heatley is digging his heels in and, yes, we are up against it [getting a moratorium]," says Hughes.
"But six months ago no one had heard of fracking and more than 6000 have signed the petition and several councils are investigating moratoria."
He rejected a suggestion that he wants New Zealand to stop all oil and gas exploration and production, but instead promotes differentiating between higher-risk deep-sea and fracking work, and continuing with the relatively shallow-depth exploration and production work, such as that in Taranaki.
He was critical of the Taranaki council's report, noting its data was self-admittedly based on industry-provided data.
He said he had tabled two separate oil company reports in Parliament claiming breach of consents, including water contamination.
He said diesel had been used in an early fracking process, and traces of highly toxic benzene, ethylene and zyalene had been found at a Taranaki well, although the latter three could have been naturally occurring.
"The [Taranaki Regional Council] report was not as comprehensive as it should have been. It's not well regulated by the Government at the moment because regional councils, who have limited resources and expertise, are charged with granting resource consents."
He said Heatley was overstating the economic benefits of expanded oil and gas exploration in New Zealand because expanded profits from the industry would go offshore to the foreign-owned companies.
Energy and resource sector lobby group Petroleum Exploration and Production Association of New Zealand (PEPANZ) supports the PCE investigation. Chief executive David Robinson said that in 28 fracking operations in Taranaki there were no incidents of drinking water or land contamination or earthquakes linked to fracking.
"We're confident that this inquiry will dispel misinformation about the environmental impacts of hydraulic fracturing and will show what great lengths the industry goes to ensure the practice is done safely with proper caution taken."
He said fracking in New Zealand does not include the use of toxic BTEX chemicals, highly carcinogenic chemicals, which are still used in some places overseas.
It's clear that if the Government cannot get the public onside sooner rather than later, the fracking issue threatens to tumble into an snowballing election issue, spurred on by images of environmental disasters. Until then, councils could face a morass of objections, litigation, and potential liabilities when resource consents for fracking are sought.
To prepare for the fracking process, a drill hole is lined with steel casing and explosive charges are detonated in the pipe to induce hairline fractures in the rock.
A mixture of about 97 per cent water and sand and 3 per cent chemicals is injected at high pressure into the fissures, allowing gas or oil to flow more freely. Shale oil and gas is generally deeper, and in less porous rock, than earlier traditional reservoirs which were closer to the surface.
However, there is growing concern worldwide that the toxic chemicals used in fracking fluid can potentially get into underground aquifers and contaminate water sources; as could some of the hydrocarbons released.
What's in the mix
Example of a chemical mix which could be used in NZ
* 98 per cent-99 per cent - Water and quartz sand.
* 1 per cent-2 per cent - Chemical additives of which about 50 per cent is a natural gel.
* Bactericide - glutaraldehyde, also used in sterilising medical equipment, soap and disinfectant.
* Gel - guar gum, also used in ice cream, toothpaste, baked goods, sauces, salad dressings.
* Cross-linker - borate salts, also used in detergents, hand soaps, cosmetics.
* Clay stabiliser - choline chloride, also used as a poultry food additive.
* Gel breaker - hemicellulose enzyme, used in washing powders, and in the food industry.
* Acidity adjuster - sodium, potassium, chlorine compounds, also used in laundry detergents.
* Surfactant - a soap chemical, found in soaps and detergents. (Source: Straterra)