The grassy field to the right is the site of a proposed gas-fired power plant in Brandywine, Md. (Evelyn Hockstein/For The Washington Post)

Mildred and Harry Kriemelmeyer moved to five green acres in southeastern Prince George’s County more than 40 years ago, after falling in love with the open spaces, pristine wetlands and untouched wilderness.

But a power plant opened two miles away in 1996, over the objections of the couple and like-minded neighbors. Another was already operating a few miles further away, and a third was recently built and will open in 2016.

Now a fourth plant is under construction, and a proposal for a fifth is being reviewed by the Maryland Public Service Commission. All five facilities would lie within a 15-mile radius in a rural area filled with farms and forests that is part of the Chesapeake Bay watershed.

“The area is being dumped on,” said Mildred Kriemelmeyer, whose property is four miles from the proposed Panda Mattawoman natural gas plant. “The people out here are just fed up.”

The Public Service Commission agreed this week to delay the approval process for the proposed facility to allow for more public comment and additional air quality analyses.

The electricity-generating plants are warmly welcomed by county governments because their owners pay considerable taxes, limit the need to import energy from out of state and hire local residents for construction and operations.

But to the Kriemelmeyers and other residents, many of whom are supportive of environmental causes, the plants are a potentially dangerous intrusion into a bucolic paradise, bringing noise, pollutants and other possible hazards.

The environmentalists have a powerful supporter in their state senator, Senate President Thomas V. Mike Miller Jr. (D-Calvert), who in a letter implored the commission to consider building the plants elsewhere. “It is clear the issue of environmental justice has not been addressed,” Miller wrote.

The power companies were drawn to the area by the open land and easy access to a natural gas pipeline and Pepco transmission lines. Their owners say they are following environmental requirements to keep pollution to a minimum.

The proposed Panda Mattawoman plant and the North Keys Energy Center, under construction a mile from the Panda site, will use the latest natural gas technology to generate hundreds of megawatts of power, the companies say.

“This plant will be the cleanest of the clean,” said Bill Pentak, vice president for investor relations and public affairs for Texas-based Panda Power Funds. “We are building a Rolls-Royce, not a Chevy.”

Both facilities would be among the five highest-assessed properties in Prince George’s, a fact not lost on local officials eager to fill tax coffers with dollars for schools, public safety and other services.

Kenny Barry, representing Local 77 of Operating Engineers, makes public comments in favor of a proposed gas-fired power plant to the Maryland Public Service Commission. (Evelyn Hockstein/For The Washington Post)

“They are very, very important,” said David S. Iannucci, economic development aide to County Executive Rushern L. Baker III (D). “This hits a home run” when it comes to the county’s need to expand its commercial tax base.

But opponents of the gas-fired plants say the concentration of emissions will compromise air quality and negatively affect the environment. They are skeptical of state environmental protections, which they say are too lax and use flawed models.

Critics wonder why there is a greater concentration of power plants in their area than in neighboring Montgomery and Howard counties. They oppose both the installation of gas pipelines under vulnerable watersheds and the use of those pipelines to transport fossil fuels extracted through hydraulic fracturing in other states.

“People are deeply invested,” said Fred Tutman, an environmentalist who lives in the area and works to protect the nearby Patuxent River. Tutman, whose family roots in the county date to the 1700s, said he and his neighbors are frustrated by the perception that, in Prince George’s, “every­thing is for sale.”

Sierra Club and Mattawoman Watershed Society members living in southern Prince George’s have scored victories in some other environmental battles.

They stopped development of a highway that they said would harm wildlife along the once-immaculate Mattawoman Creek. And they have lobbied the state legislature for more stringent regulations on coal-fired power facilities, which is one reason the Chalk Point power plant in Aquasco, Md., has decided to shift from coal-only operations to coal and natural gas.

Now activists are hoping to use new pollution-reducing rules ­issued by the Obama administration as a tool against the gas-powered plants.

But the power plants have rallied supporters, too.

At a packed hearing last week, union members, business owners and a few residents wearing “Yes to Panda” pins came out in force, touting the project’s economic merits and squaring off against detractors in an emotional volley of testimony.

“This will create jobs for locals like me who are out of work,” said Patrick Barrett of Brandywine, a unionized electrician who was laid off in January. “I’m not saying there won’t be consequences . . . but overall, the positive things outweigh the bad things.”

Panda Power officials said the project will create more than 700 temporary construction jobs and about 30 permanent ones. The company estimates that the plant will generate $45 million in tax revenue during its first 10 years of operation. It has hired a local firm to meet and build relationships with churches, affected homeowners and businesses.

“I am completely in favor of this power plant!!!” said a letter of support from resident Eugene Antonioli, who owns a business on the road where the plant would be built.

After listening to community concerns, Pentak said, Panda modified its project, agreeing to reduce the visibility of the proposed plant by adding more landscaping, to use reclaimed wastewater instead of potable water to cool the plant and to include emissions-monitoring systems that meet state standards.

But Henry Cole, a former Environmental Protection Agency air quality scientist who lives nearby, said the models used to estimate pollution omit critical sources, such as the diesel- and gas-powered vehicles needed during construction and methane leakage from gas pipelines.

State environmental officials said they reviewed Panda’s project and developed 58 pages of conditions, including measures to offset emissions of nitrogen oxide and other pollutants linked to respiratory problems and ozone formation.

“We’ve tried to be transparent and open, and we’ve listened and talked,” Pentak said. “We’ve tried to do this the right way . . . and [not] just try to cram something down someone’s throat.”