Opponents of Newport Beach's residential dock-fee increases reiterated their plans this week to sue the city if the recently passed increases aren't reconsidered.

Attorney and state Republican Party Vice Chairman Steve Baric, acting on behalf of the Stop the Dock Tax group, alleged in a letter sent Thursday that an ad hoc City Council committee met and discussed the dock fees in violation of California's open meetings law, the Ralph M. Brown Act.

The council, in voting to increase fees for residential dock owners on public tidelands Dec. 11, acted based on recommendations from that committee, according to the letter.

"We ask that this council put this matter back on its agenda for reconsideration after a meeting of the committee has [been] conducted that respects the Brown Act, the council's own rules and the fundamental principles of open government...." Baric wrote.

The city has argued that the committee was a "working group," of three council members, which is not a quorum of the seven-member council, and is therefore not subject to the Brown Act.

Furthermore, said Assistant City Attorney Michael Torres, the resolution to increase fees was actually voted on in a publicly noticed open meeting.

Baric said the city must respond to the letter, which echoed arguments Baric made in early December before the vote, within 30 days.

If the city denies the claims made in the letter, the group has 15 days to initiate litigation.

"First and foremost, we would just like to meet with the city, lay out what our grievances are, and find a solution," Baric said. "If not, we'll just have to pursue whatever remedies we have."

That could mean pursuing a court order rescinding "any action taken in violation of the Brown Act," he said.

Torres said the city is reviewing the letter.

"Our first impression is that it's completely without merit," he said.

jill.cowan@latimes.com

Twitter: @jillcowan