The Riverside Convention Center will at least double in size and downtown Riverside will see an amphitheater and 376 more hotel rooms along with housing, offices and a five-level parking structure — all by early 2023.

That development of the city-owned space around the convention center received the City Council’s blessing Tuesday, May 7. It will mean long-lasting benefits by bringing visitors to larger conventions and technology workers who will then spend money in downtown and the rest of the city, Mayor Rusty Bailey said.

“Ultimately the downtown will be changed forever, the city will be changed forever, because of the quality of this project and where it’s located,” Bailey said. “This is one of those projects that’s a game-changer for us.”

The project shows Riverside is “a world-class city” and was made possible by the Riverside Renaissance, $1.5 billion in investments to public facilities from 2006 to 2011, he said.

“This is exactly the reason the City Council and councils previously invested in the Riverside Renaissance,” Bailey said.

The development was one of two similar proposals that the City Council considered Tuesday for the parking lot next to the convention center, the landscape plaza in front of the center and the former Utilities Plaza Building.

After nearly four hours of discussion, the council voted 6-1 to approve the proposal from the Irvine-based Greens Group and Griffin|Swinerton instead of Riverside’s Sonnenblick, LLC.

Councilman Mike Soubirous voted no, saying he didn’t think estimates of how much revenue it would bring the city, particularly from parking fees, were realistic.

While city officials expect the project to earn the city money, Soubirous said he was concerned the city’s maintenance costs might exceed its revenues.

“I’m concerned about this fact,” he wrote in an email. “Other than that, both project designs are a much-needed addition to our convention center and downtown footprint.”

The council delayed a decision on some details of the proposal, notably whether to double the square footage of the Riverside Convention Center, making it 100,000 square feet, or triple its size and make it 150,000 square feet.

The smaller expansion would leave it slightly smaller than the Palm Springs Convention Center and the Ontario Convention Center, which city officials consider to be the main competitors, said Nathan Freeman, senior development project manager for Riverside. Tripling the size would put it in “elite” category alongside Santa Clara and Sacramento’s convention centers, Freeman said.

His analysis didn’t include much-larger convention centers in Anaheim and San Diego.

A $43 million renovation and expansion of the Riverside Convention Center finished in 2014 and was considered a success.

Most of the meeting consisted of debate over the merits of the two proposals. City staffers recommended the bid that wound up winning because it included more prestigious hotels — Hilton and Element by Marriott — office space, more revenue for the city and continued city control of the assets such as the new parking garage, Freeman said.

The revenue estimates are suspect, said Paul Gill, director of Client Services at architect Ruhnau Clarke, which is connected to the losing bid.

For instance, Gill said, figures Riverside posts on its website show the city spends $6.9 million a year maintaining public parking and brings in $6.5 million — a loss.

City officials explained that the convention center parking would charge more, leading Gill to suggest most people would then park in the cheaper city structures nearby and walk to the convention center.

A stream of business owners and labor union members spoke in favor of one proposal or the other, all agreeing the project overall would be a boon.

But Duane and Kelly Roberts, owners of the Mission Inn, oppose the project because they worry it will flood the hotel market and leave them unable to operate the city’s landmark hotel, said David Bristow, the family’s attorney.

Council members, backed by an analysis of the Riverside hotel market, said the Mission Inn should be OK, especially as more visitors because of the convention center and other attractions approved Tuesday. But they also saluted the Roberts for revitalizing downtown and bringing the Mission Inn Festival of Lights, credited with bringing huge crowds and about $130 million in revenue to Riverside.

“If it wasn’t for the Roberts back in 1990 to 1992 and restoring the Mission Inn, I’m not sure there would be a downtown,” Councilman Jim Perry said.

If the smaller expansion is implemented, city officials expect the city to make $4 million from the sale and $9.5 million annually in new tax revenue, parking revenue, and convention center proceeds.