In an interview with STB Wednesday, Snohomish County Executive and Sound Transit board chair Dave Somers said that West Seattle and Ballard stakeholders have to rein in their ambitions for the new line unless they can come up with more funding.

“We are going to be ever vigilant that costs are kept in control,” Somers said. “Those of us that are out in the distant future for delivery, and at the end of the system, are going to bear all the risk of cost overruns or overspending.”

Planning for the new segments of the Link system can be understood as a competition for limited resources. Projects are designed to meet a budget, rather than the other way around: Sound Transit’s mandate is to deliver a system within monetary constraints, rather than designing the system and figuring out how to pay for it later.

Somers and other Snohomish County representatives are worried that Seattle might overdraw the accounts. The agency has, so far, successfully argued to the board (and voters) that spending at the center of the system, in Seattle, carries benefits for the rest of the region.

That might be changing. Snohomish County board members are worried that they might not ever see benefits from the money they’ve put into the system if the region suffers a recession, or existing projects cost more than they should. The Everett segment of Link isn’t projected to open until 2036.

“Those of us that are out in the distant future for delivery, and at the end of the system, are going to bear all the risk of cost overruns or overspending,” Somers says. “I know people are very excited about the system, but I’ve been very clear—and I think the other board members from Snohomish County and the Eastside have been very clear—that we’ve got to stay within the budget. If you want to add some things on, you’re going to have to find some additional funding for them.”

Seattle stakeholders have generally expressed preferences for the most expensive alignments presented by ST. In West Seattle, for example, residents prefer a tunneled line near the junction. An elevated line would be much cheaper to construct, and would offer the same quality of service.

“If they want a tunnel, they’ve got to figure out how to pay for it,” Somers says. “I’ve said this before: we could easily spend the entire $54 billion Sound Transit 3 package going to West Seattle and Ballard. But we’re not going to let that happen, because we’ve got a commitment to finish the darn system. I’m not against a tunnel, but the rest of us are not going to sacrifice our portions of the system for a tunnel.”

As Somers suggests, third party funding could resolve the conflict. Rumors suggest that either or both of the City of Seattle and the Port of Seattle could kick in extra money. Somers says he and his Snohomish County colleagues would welcome Seattle-specific additional spending—as long as it’s payed for by Seattle.

“I have nothing against Ballard and West Seattle,” Somers says. “I’m excited for them. I want them to have a good system. But the costs have to be realistic.”

This post has been edited to reflect the actual time of the interview with Dave Somers.