The Saskatchewan government says there is a growing problem with oil wells in the province releasing levels of hydrogen sulphide (H2S), or sour gas, many times higher than what would kill a person.
At 1,000 parts per million (ppm), sour gas is instantly fatal.
The Ministry of the Economy said it tested 43 facilities in southeast Saskatchewan that were leaking sour gas "with average concentrations at 30,000 ppm." That's 30 times higher than the level that is fatal to humans.
In one case, a well emitted 150,000 ppm.
Provincial rules say facilities should not emit any gas or vapour containing H2S at levels any higher than 1,000 ppm.
"This is a big and serious problem," said Ed Dancsok, the assistant deputy minister for the petroleum and natural gas division of the Ministry of the Economy.
Dancsok said it's been caused, in part, by a lack of focus by the industry and the ministry, which is the regulator.
"There's been sites that have not received the attention they should," Dancsok told CBC's iTeam. "So our stepped-up enforcement actions are starting to correct that."
Dancsok said Saskatchewan's sour gas problem is now his "No. 1 priority."
Dead calves got ministry's attention
He said this issue came to the ministry's attention in a stark way in early 2013 when it learned of the death of six calves near Manor, Sask.
They belonged to Lester and Cecilia Englot, who have been raising cattle in the area for 17 years.
In 2010, Sure Energy Inc. drilled wells and built a battery site right across the road from the Englots.
They said they noticed the "rotten egg" smell of sour gas right away.
"But we thought it was normal to live like that," Cecilia Englot told CBC's iTeam, "we didn't know any better."
But in early 2013, they were alarmed when some of their calves became ill.
"The yearlings would start coughing and they'd get sick and we'd treat them," she said.
"And the next day they'd die. There was no indications of anything. We couldn't save any of them that got sick."
They called Phil Murray, who has been a vet in the area for about 40 years.
He said H2S doesn't leave any telltale signs in a carcass.
After examining the animals, however, he could see no other reason for their demise.
"It's my belief that a cloud of H2S moved from the battery to the corrals where the cattle were kept and couldn't move from them, and some of them got enough H2S, it killed them," Murray said.
On March 19, 2013, Sure Energy paid the Englots $8,330, which the Englots said was the cost of the calves that died.
A document provided to CBC's iTeam by the Englots shows the payment was for "inconvenience and discomfort as a result of the unexpected release of solution gas from the battery site … which resulted in a noticeable and unpleasant odour for an extended period of time."
The document makes no mention of dead cattle. It goes on to say, "the payment herein referred to shall not in any way be construed as an admission of liability, either in fact or in law, on the part of Sure Energy Inc."
The Englots said the ministry contacted them to report it had detected H2S from the nearby site at levels many times higher than would kill a person.
On May 17, 2013, it ordered Sure Energy Inc. to decommission and abandon the site.
Later that year, Sure Energy Inc. was bought out by another firm. The new owner didn't respond to CBC's request for comment.
Dancsok said the incident with the dead calves "got our attention." But it wasn't the only reason for alarm.
Growing complaints about H2S
He said over the past few years, the ministry has received 60 complaints about odour and nose and eye irritation. Most of them came from southeast Saskatchewan, many of those from the Oxbow area.
According to an email from the ministry, in 2012 a health-care professional complained of "headaches, nausea and vomiting," as one example.
On March 1, 2013, then minister Tim McMillan wrote a letter to every oil and gas operator in the province, reminding them "to actively monitor and take measures to prevent H2S emissions and ensure compliance obligations under the applicable regulations are adhered to."
Dancsok said that in the past, most Saskatchewan oilfields were considered "sweet" and didn't emit sour gas. But he said as they age they're becoming sour and producing hydrogen sulphide at an increasing rate.
He explained that even with the increased volume of sour gas, the industry ordinarily has a simple solution; to flare the gas or have it treated at a facility.
But he said a booming oil industry has strained the resources of many companies, which are having a difficult time attracting enough qualified staff in order to ensure facilities are well-maintained and don't leak.
"When you're growing you just don't have enough boots on the ground to get this work done or proper training, proper education of people to know that this is a problem," Dancsok said.
The association that represents many oil companies in Saskatchewan, the Canadian Association of Petroleum Producers, disagrees with that assessment.
Brad Herald, vice-president of western Canadian operations, said there may have been temporary shortages.
But he said "industry overcomes that [labour shortage] by temporary accommodation, bringing in workers from other areas."
Ministry audits the industry
In response to these growing concerns, the ministry audited 22 random wells in southeast Saskatchewan in the summer of 2013.
"And 21 of them failed," Dancsok said.
He explained that failure doesn't necessarily mean that the wells were emitting sour gas. In some cases spills were not properly cleaned up. In other cases there was inadequate signage. But in six instances the wells were emitting sour gas.
"So that was telling us we need to do more work, of course."
Dancsok said a test commissioned by the ministry shows that six per cent of the 80,000 wells in Saskatchewan are sour.
He said that in the summer of 2014, the ministry audited 84 "critically sour" sites located near where people live.
Of those, 59 facilities, or 70 per cent, failed. The ministry issued 24 orders to correct the problems and it suspended operations of another 35 wells.
Dancsok said the next step will be a sweep of 10,000 wells across Saskatchewan this year. He said that in addition to his 16 full-time inspectors, he's assigning four or five others to help with the work.
Herald said the industry supports the province's audit blitzes and its increased enforcement.
"We have been foursquare behind those efforts," Herald said.
Despite all the problems that have been identified, Dancsok said "we have no serious human health issues that have been reported to us from the general public."
However, there may be one notable exception.
Kara Bunz from Wawota said her husband died of sour gas poisoning while testing a well last May.
Bunz said she knew something was wrong, on the morning of May 22 last year. Her husband didn't answer her texts or phone calls. Read more about that day here.