The City of Seattle may have just seriously impeded Shell's ability to moor its Arctic drilling fleet in Elliott Bay—for now.

At the Climate Solutions annual breakfast this morning, Mayor Ed Murray announced that the city's Department of Planning and Development reviewed the 20-year-old permit allowing Shell to use Terminal 5, and found that hosting Arctic drilling equipment is not in compliance with it.

Mayor Murray said that the city has instructed the port to reapply for the permit to allow Shell's fleet on the Seattle waterfront.

"I have also urged the port this morning, as I did last week, that this is an opportunity to reconsider their decision, versus bringing in a huge symbol of everything that's wrong with our energy policy into our port," Mayor Murray told The Stranger.

"We haven't seen the [DPD's] interpretation yet," Port of Seattle spokesperson Peter McGraw said. "All I've gotten here is the press release from Ed and on [DPD Director Diane Sugimura's] letterhead here. We just have to take the appropriate amount of time to review it, and we'll go from there."

Paul Queary, spokesperson for Foss Maritime, the lessee shipping company working with Shell, said that the Port of Seattle told Foss that the activity the company was considering for Terminal 5 was consistent with the permit. Foss would proceed as planned, he said. "At this point, this is a dispute between the city and the port."

In March, the mayor and the city council expressed concern that the Port of Seattle's decision to host Shell might conflict with something called the Shoreline Substantial Development Permit, which was issued to the port over the use of Terminal 5 in 1996. The mayor instructed the DPD to review the port's new leasing decision.

"The current permit, called a Shoreline Substantial Development Permit, designated Terminal 5 as a 'cargo terminal'—usually meaning goods are stored and ultimately transferred from this terminal to other carriers or locations," the original press release read. "But if the Arctic drilling fleet is actually being moored and repaired at Terminal 5, there could be significant and adverse impacts on the surrounding environment."

So what happens now? The port could vote to reapply for a new permit, or challenge the city's decision in court. (The port commission could also vote to rescind the lease.) "And I suppose the port could also choose to ignore us and we would look at what actions we could take," Murray said.

But if the port chooses to reapply for the permit, it'd take weeks or months, Murray added.

And delayed timing could threaten Shell's plans if the company doesn't find an alternative. According to the exploration plan Shell submitted to the Bureau of Ocean Energy Management, its vessels are meant to be in the Chukchi Sea off Alaska's North Slope by July 1.

"I think oil rigs and using our ports for oil rig equipment is sort of like the old Rust Belt in the Northeast and the Midwest," Murray said. "The industry changed, and I think we should be using that port to build the industry of the future. It's time to turn the page."

UPDATE: You can read the DPD's interpretation (if you really like that kind of thing) here.