Conor O’Neill’s Irish Pub in Boulder is closing — this time for good.

The bar’s owner, Colm O’Neill, posted the news to the establishment’s Facebook page at 11 p.m. Thursday night.

“While business has increased over the last six months, our sales are unfortunately not at the level to make Conor O’Neill’s a viable business any longer,” the post read. “We are so thankful for the 18 years we have served this community and the last six months have truly been an amazing gift.”

The last day of business for the pub will be April 22. Doors will be open on Sunday “for anyone who wishes to purchase a part of Conor’s history.”

“The bar has a lot of knickknacks, old Irish signposts and such,” said O’Neill. “For years people have been asking us if they could buy things from the bar, so we thought we’d have a little auction of sorts.”

Conor’s closed temporarily in September after failing to negotiate a lease with landlord W.W. Reynolds. The two parties were able to reach an agreement the following week in which the bar would pay a lower rent while it built business back up. It reopened that Friday.

Luke Arrington, director of property and asset management at W.W. Reynolds, said Conor’s is still operating under that lowered rate. O’Neill informed the company last week that it would be closing.

Construction on W.W. Reynolds’ building next door closed the back room and patio at Conor’s for 18 months, impacting business. Rent was decreased during that time but went back up following its completion. However, business was slow to rebound, prompting the first closure and resulting in public outcry.

“We got an outpouring in the fall,” O’Neill said. But after a small uptick in business, the crowds once again began to thin. “They found other places to go.”

Boulder’s downtown looks dramatically different than when Conor O’Neill’s opened in 1999, taking over at 1922 13th St. from The James Pub and Grill. The transformation from pubs and grills to bistros and breweries contributed to Conor’s decline, O’Neill believes.

Sean Maher, CEO of the Downtown Boulder Partnership, agrees.

“The west end was a pretty sleepy little area 20 years ago,” he said. “Now, there’s just a lot more competition downtown.”

Maher and O’Neill remain committed to continuing a Conor’s tradition: The World’s Shortest St. Patrick’s Day Parade, which the bar took over sponsorship of in 2000. And O’Neill has only positive feelings about his bar’s time in Boulder.

“We had a good run,” he said. “Eighteen years — that’s a good run.”

Shay Castle: 303-473-1626, castles@dailycamera.com or twitter.com/shayshinecastle