CEDAR RAPIDS, Iowa — City, county and community leaders Wednesday broke ground on the city’s new downtown Riverfront Amphitheater that, when complete in 2012, will be part outdoor entertainment venue and part flood-protection levee.

On community wish lists for more than a decade, the $8.2-million amphitheater project is expected to feature more than 50 events a year and attract thousands of people to the city, Mayor Ron Corbett told a hundred or so officials and citizens on hand for the lunchtime groundbreaking on the west-bank of the Cedar River upstream from the Police Department.

Corbett said the amphitheater project would serve as a “catalyst” for other west-side development.

The amphitheater will be designed to hold between 3,000 and 5,000 for national touring shows, but also will be used for an assortment of smaller concerts and events. It will be the largest such venue of its kind in Iowa. The Simon Estes Riverfront Amphitheater in Des Moines lists its seating capacity at about 2,000.

The amphitheater will feature a permanent stage and a few rows of benches made of stone or concrete that will be designed to take on flood water. A lawn also will be used for seating. A walkway from the amphitheater will lead to a new park, Festival Park, which will provide parking and space for events like the city’s BBQ Roundup during the annual Freedom Festival.

City Manager Jeff Pomeranz on Wednesday called the amphitheater project “a true public-private partnership.”

The project has received a $1.9 million worth of land from the city and Linn County with the city contributing an additional $1.675 million and the county an additional $10,000.

In addition, the project has secured a $1.6-million state I-JOBS grant and a $1.075-million state River Enhancement Community Attraction and Tourism grant. The project also is receiving $2 million in private donations, including a $1-million grant from the Hall-Perrine Foundation of Cedar Rapids and several large corporate gifts.

At the Wednesday event, Jack Evans, president of the Hall-Perrine Foundation, said the decision to financially support the amphitheater project was an easy one for the foundation’s board for two reasons.

“Firstly, the natural beauty of the facility sitting right here,” he said, with the downtown skyline just across the river. “We were very impressed just with the ambiance that it would create for the downtown.

“And the second one was the diversity of the performers that will be here. We felt it will add richly to the arts and cultural fabric of Cedar Rapids and Linn County.”