WASHINGTON — Electric utilities in Nebraska and Iowa will be watching closely this morning when the Environmental Protection Agency releases groundbreaking new rules aimed at cutting the carbon pollution of existing power plants.

While not disclosing details ahead of its announcement, the EPA has said its proposal represents a “common sense and flexible approach” that cuts pollution and protects public health while furthering economic growth and innovation.

Still, there is plenty of anxiety in the country’s coal-dependent heartland, where Nebraskans and Iowans are accustomed to relying on coal-fired power plants for about two-thirds of their electricity and railroads such as Union Pacific and Burlington Northern make money hauling load after load of coal out of Wyoming and across the states.

Businesses and households in both states enjoy some of the nation’s lowest power bills, in part because coal is such a cheap way to produce electricity.

A recent University of Nebraska-Lincoln report prepared on behalf of the Nebraska Public Power District highlighted coal’s impact on the state’s economy.

There are 839 workers employed at Nebraska’s seven coal-fired power plants or at other locations directly tied to coal-fired electricity generation, with annual wages and benefits of approximately $87 million.

Factoring in railroad transportation boosts coal-related economic activity into the billions of dollars, the report said.

The Nebraska Legislature passed a resolution in April calling on the EPA to allow states to take the lead in tackling carbon emissions and to set less stringent standards or longer timeframes for requiring coal-fired plants to comply.

State Sen. Jim Smith of Papillion, a former Omaha Public Power District manager, traveled to Washington, D.C., last week along with lawmakers from Georgia and Kentucky to represent states that have passed such resolutions.

Smith told The World-Herald that if the EPA pushes industry to make unrealistic reductions in carbon emissions quickly, the result will be significantly higher electricity rates that Nebraskans can’t afford.

He also said changes could mean less reliable power.

“If they prematurely shut down power plants, then something’s going to have to be there to replace it,” he said. “And wind will not replace a baseload generation like coal, because it’s not reliable. You can’t count on it from moment to moment.”

Troy Bredenkamp, general manager of the Nebraska Rural Electric Association, said his members are concerned that the new rules could result in expensive overhauls and possibly even force them to shutter their oldest facilities.

“That’s the part of our fleet that does keep everyone’s lights on 100 percent of the time,” Bredenkamp said of their coal-fired plants.

Their customers are mainly farmers who need a steady, reliable supply of electricity to pump irrigation water, dry corn and do other agricultural tasks that are concentrated in a few months of each year.

Proponents of the regulations say that fears are overblown — and that something has to be done about changes in the global climate fueled by the buildup of the greenhouse gases pouring out of those coal-fired plants.

In Nebraska and Iowa, for example, winters have gotten warmer, spring has been coming earlier, and temperature records for warm weather have begun outpacing those for cold weather.

The year 2012 was Nebraska’s hottest, driest year on record, which led to the state’s worst year for wildfires. That summer, McCook set a temperature record that exceeded those of the Dust Bowl years and Omaha had its driest July on record.

In Iowa, rainfall patterns have changed, with deluges accounting for a greater share of rainfall — resulting in greater soil erosion and problems with flooding. Iowa farmers have also found themselves contending with wetter spring weather, reducing the number of days available for planting.

Warmer weather also has public health consequences. In Omaha, from 1995 through 2009, the allergy season has grown by an average of 11 days.

Those who support tougher EPA rules have studies indicating that lower emissions would ultimately boost economic activity.

The Natural Resources Defense Council, for example, says energy-efficiency programs would create jobs and ultimately save consumers money while cutting down on emissions.

But Bredenkamp said his members already have done a lot on the efficiency front.

For example, one program allows rural public power districts to manage farmers’ irrigation wells and shut them off during peak hours so they don’t overload the system.

“I’m not sure how much more efficient the system can get and still maintain reliability and affordability,” Bredenkamp said.

Regi Goodale, director of regulatory affairs for the Iowa Association of Electric Cooperatives, said his group already has started the process of working with state officials and power plants on what an Iowa compliance plan might look like.

His members expect rates to go up.

“It’s not a question of if they will, it’s a question of how much,” he said.

Iowa has made big strides with wind and solar energy, but Goodale said there still is a need for a consistent source of power.

“The reality is that we need some firm generation to help back that up when the wind’s not blowing and the sun’s not shining,” he said.

The Omaha Public Power District could be well positioned to comply with the new rules, said Tim Burke, OPPD’s vice president of customer service and public affairs.

It is adding 600 megawatts of wind-generated electricity to its portfolio, reducing its reliance on coal and nuclear power — partly because the utility expected that more stringent rules were on the way.

By 2018, OPPD estimates, 33 percent of the electricity it provides customers will come from renewable sources.

Even before details of the plan are clear, Republicans on Capitol Hill already have been denouncing the administration’s plans as a war on coal.

Rep. Lee Terry, R-Neb., said it appears that the administration wants to force the power industry to move away from coal. That will mean higher costs that will be passed along to customers, he said.

“There’s no doubt NPPD is going to have to raise rates,” Terry said.

While Terry is a proponent of using more natural gas, he said the transition needs to happen through the natural phasing out of old plants.

“This is just a guillotine coming down,” he said.

Lawmakers on both sides of the aisle have been pushing the EPA to allow more than the standard 60 days of public comment on the agency’s proposal.

All four senators from Nebraska and Iowa signed a letter asking for an extended comment period.

Terry had one prediction about today’s announcement.

“There will be a great deal of energy expended in criticizing the rule and complimenting the rule on Monday afternoon,” Terry said. “That’s the only (certainty). If we could harness that, we could power a lot of buildings.”

World-Herald staff writer Nancy Gaarder contributed to this report.