OLYMPIA — It may take Gov. Jay Inslee longer to circumvent lawmakers and impose a cap on carbon emissions than he’s expecting.

The governor directed the Department of Ecology last week to begin developing a hard limit on emissions using his rule-making power under existing state laws.

He pledged the process would be open with plenty of opportunity for interested parties to weigh in — and he expected to be finished in about a year.

But the man leading the effort says it could take twice as long because of the complexity and controversy enveloping the issue.

Stu Clark, the air quality program manager for the Department of Ecology, said his team must craft the rule essentially from scratch as there’s no template for such a regulatory feat.

“A complex rule like this can typically take us 18 months to 24 months to do,” he said. “It must be built from the bottom up. Everybody will get their say.”

While air emissions are regulated for a handful of industries, such as pulp and paper mills, for the most part the state must figure out who will be covered by the new regulations and then what is practical and possible for them to achieve in terms of reductions, Clark said.

It is likely the eventual rule will not apply to all emitters which will add a degree of complication to the regulatory calibrations, he said. Cars, for example, are the single largest source of pollution-causing emissions but aren’t likely to be placed under any cap, he said.

Procedurally, once all that work is done and a draft rule is completed, it would be formally released. The state would then have 180 days to gather public comments at the end of which Inslee would have to decide whether to make it final.

A spokeswoman for the governor didn’t dispute Clark’s assessment of the challenge ahead though she emphasized the governor is resolved for the process to be carried out with deliberative speed.

This cap would be the centerpiece of Inslee’s efforts to combat climate change in the wake of his failed attempt to pass a cap-and-trade policy earlier this year.

“This is not his preferred approach,” said Inslee spokeswoman Jaime Smith. “I think the incentive all along has been the acknowledgement that we need to do something about this issue.”

Meanwhile Monday, President Barack Obama announced new federal rules to limit emissions from the nation’s power plants. Inslee praised the president and issued a statement saying the policy complements his approach in the state to fighting climate change.

“Here in Washington we’ll go further,” Inslee said. “We will cap carbon pollution using our state’s own Clean Air Act, we will continue to invest in clean technologies and we will promote a smarter grid and cleaner transportation alternatives.”

The cap sought by Inslee is intended to help the state meet emission limits contained in a 2007 law.

Under that law, the state must reduce its overall greenhouse gas emissions to 1990 levels by 2020 and be 50 percent below that benchmark by 2050.

Washington is making headway toward attaining the first target. In 1990, its greenhouse gas emissions totaled 88.4 million metric tons. It rose to 101.6 million metric tons in 2007 but had declined to 92 million metric tons in 2012, according to ecology department figures.

The problem with the 2007 law is it didn’t spell out how the state should meet the standards.

Earlier this year, Inslee proposed a cap-and-trade approach that lawmakers rejected. That plan targeted roughly 130 of the state’s largest polluters and would have required them to buy credits for emissions through an annual auction. Money from sales of the credits would go into the state budget.

The rule now getting developed would not charge emitters so it would not raise revenue for the budget, according to the governor’s office

Environmentalists, who cheered Inslee’s announcement as bold and decisive, said the one-year timetable is ambitious and possible.

“That is the expectation and I will hold him to that,” said Becky Kelley, president of the Washington Environmental Council. “The nature of the tool the governor has largely been forced to use is a tool he needs to use decisively.”

The state isn’t starting totally from scratch because there’s ample knowledge on sources of emissions, options for reduction and positions of the stakeholders in this debate, said Ross Macfarlane, senior ad visor at Climate Solutions in Seattle, a nonprofit that promotes clean energy and climate change policies.

“This is aggressive but not impossible,” he said. “Will it require the governor continuing to put pressure on the administration of the Department of Ecology? Absolutely.”

Business leaders are concerned that some firms will be harmed by the results if the process is too hurried.

“Without having any details, how do you go from scratch to a rule in a year?” asked Brandon Housekeeper, director of governmental affairs on environmental issues for the Association of Washington Business. “One year just seems aggressive on his part.”

Housekeeper said he’d prefer the governor use the type of collaborative approach that he did for drafting a rule for new water quality standards tied to the consumption of fish. That allowed for the full input of affected parties.

“I would argue it is going to be equally as complex, maybe more, than the water quality rule,” Housekeeper said.

That took much longer than a year to complete and the governor on Friday announced he wasn’t going to press ahead with the clean water rule.

That was “quite a different situation,” Kelley said noting adoption of the clean water rule was tied to a toxics control bill that lawmakers did not pass.

“He had constructed a grand bargain with legislators and didn’t get it,” she said. “With this, he is in control of the situation.”

Jerry Cornfield: 360-352-8623; jcornfield@heraldnet.com