We’re getting a better idea of what Gov. Jay Inslee envisioned when he announced last month he would use his executive authority to impose a binding cap on carbon emissions in Washington.

And the bottom line is that by next summer many Washington businesses could face new limits with which they must comply.

Inslee sent a letter Thursday to the director of the Department of Ecology offering “some guidance and my expectations about how this program needs to work.”

Inslee doesn’t specify what industries he wants covered by the rule but he does note greenhouse gas emissions in Washington are generated mostly from energy production and use, manufacturing, and transportation. The latter he says is the largest contributor.

“I ask that you carefully assess what sectors and facilities should be covered by the rule in order to regulate the state’s largest contributors of carbon pollution to achieve the greatest emission reductions in an efficient and effective manner,” he wrote to director Maia Bellon.

Of critical importance to him is the cap must decline over time in order to help the state meet reduction targets set by the Legislature in 2007. And he said those entities covered by the rule must “have a variety of compliance options available to them in order to keep compliance costs low.”

He also expressed his desire to see a draft rule out in January and adoption next summer.

“I believe a disciplined and focused effort can result in a final rule adoption by summer 2016 and ask that you do everything possible to achieve that timeline,” he wrote.

That is an aggressive timetable.

The state spent nearly three years drafting and debating new water quality rules tied to the amount fish people consume before Inslee decided last month to not enact the changes.