On a tiny island smack in the middle of Brookdale Drive in suburban Upper St. Clair sprouts a 90-year-old natural gas wellhead that looks like a rusty Rube Goldberg drinking fountain gone to weed.

There's another gas well shielded from view by 14 newly planted yews in a manicured front yard on Rocklynn Place in Mt. Lebanon; a couple of others near the Castle Shannon Light Rail Transit stop; a handful in back yards in Bridgeville, and hundreds of oil and gas wells sprinkled through Penn Hills, North Fayette, South Fayette and Plum.

There's one in a commercial business parking lot along the Allegheny River in Oakmont. A dozen wells are scattered out of sight like errant tee shots around the Oakmont Country Club where the women's U.S. Open golf tournament will be played next year and most likely the men's U.S. Open in 2016.

Allegheny County will never be confused with the Texas and Oklahoma gas and oil fields for production volume, and to date there has been only one drilling operation in the county aimed at the deep Marcellus Shale formation.

But surprisingly, its suburban and exurban landscapes contain more than 1,400 relatively low production "marginal wells," also known in the industry as "stripper wells." By definition, gas stripper wells produce less than 60,000 cubic feet of gas a day.

A number of those relatively shallow, 1,700- to 2,500-foot-deep wells were developed in Allegheny County over the last 30 years, but many others are much older. They were drilled in the early 1900s to supply booming glass and steel industries before the construction of the housing developments, commercial districts, parking lots and yards that have grown up around them.

Those older wells have had a long if unspectacular lifespan because Pennsylvania's unique, densely packed sand and rock formations release gas and oil deposits slowly.

"It was said that owning Pennsylvania gas wells was like owning bonds because they guaranteed income to the owners for decades and decades," said J. Scott Roberts, deputy secretary for the state Department of Environmental Protection's Office of Mineral Resources. "So I'm not surprised there are all those old wells that are still producing."

Mr. Roberts said the state's marginal oil and gas wells are part of a significant national resource. According to a study in 2008 by the Interstate Oil and Gas Compact Commission, stripper wells supplied almost 8 percent of the 23 trillion cubic feet of natural gas used in the U.S. in 2007 and 4 percent of its daily 20.7 million barrel crude oil supply.

Pennsylvania has more than 70,000 active oil and gas stripper wells, second most in the nation behind Texas, according to the study. It has 52,700 marginal gas wells, more than any other state. But its production rate of just under 8,000 cubic feet a day per well ranks 25th among the 28 states with stripper well production, further evidence of the state's "tight" geology.

The state ranks eighth in the nation for oil wells, with 18,200 -- all classified as stripper wells. Again, the average daily production rate of half a barrel per well ranks 27th among 30 states where such wells operate.

Stephen Rhoads, president of the Pennsylvania Oil & Gas Association, the state independent oil and gas producers' trade group, said low productivity per well is why there has been so much drilling in Pennsylvania. He said income earned from the old marginal well production is essential to new oil and gas development in the state.

"The entire oil and gas industry in Pennsylvania is essentially a stripper well industry because of the geology," Mr. Rhoads said. "The wells can remain marginally productive for many years because the cost of operating is relatively low. But companies that wish to grow must use the cash flow from flush production times to recapitalize and keep drilling."

Mostly the wells go unrecognized and unnoticed by their neighbors except for rare instances when something goes wrong. In 2007, gas seeping from old, improperly plugged abandoned wells caused precautionary evacuations of homes in Versailles, a town where 660 gas wells were drilled in 1919.

But even when the wells don't present safety problems, they're not always welcomed by their neighbors, even though the wells often were there first.

Raymond Langer is a third-generation oil and gas man from Coraopolis who owns two gas wells and 13 oil wells, including an oil well drilled by his grandfather in 1927 that's still producing two barrels a day. He said the residents are the biggest impediment to the local industry.

"This is a good, clean life, and the old wells that produced maybe 400 barrels a day when they were drilled just hang on, producing a barrel or two a day, and can stay right there if you take care of them," said Mr. Langer, 69, who recently sold four producing wells to a developer who capped them so he could build housing.

"The public is our biggest problem. They all want the gasoline for their cars but they don't want to see a well in their back yard. We're getting crowded out."

Terry Jacobs, president of Penneco Oil Co. Inc., said the Delmont-based company has hundreds of wells in seven Western Pennsylvania counties and more than 150 wells in Allegheny County, but tries to avoid drilling in residential areas. He said the majority of the company's wells in Allegheny County were drilled in the last 15 years, although some date to the 1920s.

"We have a few wells right up next to houses but very few," Mr. Jacobs said. "We don't like to do that, drill close to houses, and the homeowner doesn't either, even though most wells don't make any noise or smell. But there are a number of people who don't want things like that in their back yards."

Or their front streets.

Geralyn Sneath has been asking the state Department of Environmental Protection to order the removal of the rusty, nonproducing "shut in" gas well in the middle of Brookdale Drive near her home for several years, since neighbors smelled gas.

That problem was fixed when a supply line was capped. But she maintains that the well should be plugged and dismantled because its owner, Pete Broge, has failed to comply with the state's time limits for getting it into production.

The state DEP issued two notices of violation to Mr. Broge because the well hasn't been producing, but hasn't seized and capped the well under its Orphan Well Plugging Program.

"The well hasn't produced in over five years but the owner has on several occasions sent reports describing his efforts to produce and sell the gas," said DEP spokeswoman Helen Humphreys. "He's been unsuccessful to date but this is a property rights issue."

She said 8,000 to 10,000 abandoned wells across the state have been identified as possibly eligible for the Orphan Well Plugging Program. Action to plug those wells is taken based on public safety concerns.

"We have to prioritize," Ms. Humphreys said. "We look at the public health and safety risk and that's not the case for this well."

Mr. Broge, who owns nine wells in Allegheny County, all but two of which are producing gas, said he would have plugged the well on Brookdale Drive if there was a safety issue. He said he's had problems securing a right-of-way route to a nearby gas pipeline and hopes to come up with a solution soon that could involve removal of the well.

Mr. Broge has had no such problems at the well he owns on Rocklynn Place in Mt. Lebanon, which is 22 feet from the front door of Randy Torcasi.

Mr. Torcasi said the previous well owner allowed it to "erupt and make a sound like a tornado" but Mr. Broge has installed new equipment that has eliminated that problem.

"The well has been there since the 1920s. Our house was built in 1977. Pete has been receptive to our needs and I don't have a problem with it in my front yard," said Mr. Torcasi, 59. "I just want to paint the wellhead so it blends in better with the ivy out front."