On Sept. 14, 2009, natural gas operators finished drilling the 3H well on the Lbros farm in southwest Pennsylvania. Just over four months later, they "fracked" it by injecting more than 6 million gallons of chemical-laced water into the 2-mile-plus-deep well.

It wasn't until nearly a month after that, on Feb. 22, 2010, according to public records, that Pennsylvania's Department of Environmental Protection received paperwork showing that drilling and fracking on the Range Resources well were completed. Before that, it's not clear what the department knew about the well's evolution, other than that drilling had begun the previous June.

That reporting delay appears to violate a Pennsylvania law that requires drilling companies to submit a "well record" to the DEP no more than 30 days after drilling is completed. Those records report the depth of the well and the geological formations the drillers encountered. They also contain details of the cement and casing that surround the well and prevent gas and fluids from leaking and polluting aquifers.

DEP spokeswoman Jamie Legenos said some of the department's regional offices haven't enforced the law. But she said the reporting delay doesn't present a danger because in most cases the department relies on inspections, rather than the reports, to ensure that wells are drilled to code. When inspectors can't make it to a site, she said, they keep in touch with drillers by phone and e-mail.

The 3H well on the Lbros farm has never been inspected, according to the DEP's online reporting system, which was last updated in August. Neither have three other wells drilled on the farm.

Legenos said the reporting discrepancy stems from the fact that the well record is on the same piece of paper as a form that companies must file after wells are hydraulically fractured, the process that injects them with millions of gallons of water mixed with sand and chemicals to release gas from the earth. The two processes are often separated by several months, and some DEP offices have allowed companies to submit both records at once.

Matt Pitzarella, a spokesman for Range Resources, one of the state's largest drillers, said Range has followed that procedure with all its well records and was unaware it may have been violating state law. Pitzarella said the company will be "fine with either format, but it probably warrants further discussion with the incoming administration." Pennsylvania's new governor, Tom Corbett, appointed a new DEP secretary in January.

In an e-mail, Legenos said the DEP plans to address the reporting discrepancy, but she didn't say when. "With our increasing enforcement personnel reporting compliance will be more rigorously enforced."

The DEP's enforcement staff has increased nearly four-fold in the past two years, to about 130 people, 65 of whom are inspectors, Legenos said. But the state is still struggling to keep up with the natural gas boom in the Marcellus Shale, the gas-bearing rock formation that stretches under large parts of New York, Pennsylvania, West Virginia and Ohio.

More than 21,000 oil and gas wells have been drilled in Pennsylvania since 2005, including some 2,700 last year. The DEP inspected about 9,000 wells in 2010, but Legenos could not say how many of those were newly drilled and how many were older wells still in operation.

Deborah Goldberg, an attorney with the environmental group Earthjustice, said Pennsylvania needs to keep increasing its inspection staff.

"I just don't think they have anywhere near the number of inspectors they need so they can be doing timely inspections of all the wells they've been permitting," she said. The department issued more than 6,100 well permits last year.

Other states have also had trouble keeping pace with the rapid growth of gas drilling, as ProPublica reported in 2009. Colorado and Wyoming both updated their regulations in recent years, and each state requires drillers to submit some type of report within 30 days of drilling. But in Colorado, too, there aren't enough inspectors to cover the state's wells, said David Neslin, director of the state's Oil and Gas Conservation Commission.

Legenos said most of Pennsylvania's wells are inspected during drilling operations. But that leaves unanswered what happens when they aren't. State law says the department's "intent" is to have inspectors present at each of a number of points in a well's lifespan, including drilling and fracking. Legenos did not say how often that intent is met.

ProPublica submitted a public records request for a small selection of Well Record and Completion reports for Range Resources. The request covered about six months of drilling and initially produced reports for 42 wells, including Lbros 3H. When we told the DEP in December that some reports seemed to be missing from our request, the department produced six more. This week the department said it was still looking to see if more requests may be missing.

Using those records, along with the DEP's online reporting system, we determined that most of the wells were inspected at least once during drilling. However, none were inspected during fracking. And six had not been inspected at all as of August 2010. Those numbers do not necessarily represent the inspection rates of gas wells across Pennsylvania.

Details contained in the Well Record and Completion reports are critical to determining the integrity of a well, said Susan Harvey, a petroleum engineer who has consulted for environmental groups. The highly pressurized fracking fluids tend to follow the path of least resistance, she said, and a faulty cement job can provide an easy exit. Bad cementing can also contribute to a blowout, as is suspected in the BP Deepwater Horizon disaster.

Cementing problems are believed to have led to the 2009 explosion of a water well and the contamination of drinking water near the town of Dimock, Pa. In that case, the DEP cited drillers for faulty cementing and casing and also for turning in late Well Record and Completion reports.