The San Gabriel Valley city of Diamond Bar has agreed not to challenge a proposed 75,000-seat National Football League stadium in the neighboring City of Industry in exchange for up to $60 million over the next 30 years.

Stadium developer Majestic Realty Co. hopes the April 7 settlement between Diamond Bar and Industry will inspire other project opponents including the city of Walnut, which has filed a lawsuit also to step aside.

“Diamond Bar’s strategy is a textbook example that any city faced with a major project should follow,” said John Semcken, project executive for Majestic, a City of Industry real estate developer owned by billionaire Ed Roski Jr.

The $800 million project including the stadium and nearly 3 million square feet of office, retail, medical, entertainment and restaurant space is planned for a 600-acre site owned by the City of Industry northwest of the Pomona (60) Freeway. Majestic only plans to move ahead with the project if it is able to attract an NFL team, which has so far not happened.

The site borders Diamond Bar, a wealthy community at the extreme east end of the San Gabriel Valley. Under the settlement, Diamond Bar will receive $20 million to mitigate traffic generated by the stadium and millions more for other community projects. It could receive an additional $700,000 for parks and recreational facilities for each year in which at least 24 events, or 10 or more NFL games, are held at the stadium.

Diamond Bar City Manager James DeStefano said the settlement was agreed upon after the city realized that a legal challenge might ultimately prove futile.

“We understood that a legal challenge, even if successful, would not necessarily stop the project but simply slow it down,” DeStefano said. “A negotiated settlement not only advances the issues, but provides community benefits that will be utilized in our community for years to come.”

The settlement includes $1 million to be paid for a new athletic field at a local middle school, $300,000 to cover legal fees, and funds to construct a 6-foot block wall and landscaped berm to lessen visual impacts in neighborhoods near the stadium.

Industry City Manager Kevin Radecki said the agreement was a long time coming.

“There was lots of going back and forth,” Radecki said. “I think the settlement is a good thing for both parties. It’s a situation where they got what they were looking for, and we got what we were looking for.”

Radecki and Semcken said the money paid to Diamond Bar will come entirely from the proceeds of the stadium, including ticket and parking taxes, under an agreement that has not yet been formalized. Should those revenues fall short, Semcken added, Majestic will cover the difference.

“The City of Industry will not be at risk. We will pay for it all,” he said.

It’s unclear, however, whether such a settlement would be attractive to Walnut, as well as a group called Citizens for Communities Preservation Inc. Both have filed lawsuits challenging the stadium project’s environmental impact report. The suits, Semcken acknowledged, could seriously delay completion of the stadium, originally planned for 2012.

At issue in the lawsuits is the validity of the EIR process followed by Majestic and Industry officials. Prior to last April’s unveiling of the stadium plan, an environmental report had been approved for a 5 million-square-foot commercial and industrial center at the site. Majestic later submitted a supplemental EIR approved by city officials studying the effect of the stadium, and the various retail and entertainment attractions.

Both Walnut and the citizens’ group contend that an entirely new report should be completed on the stadium proposal.

“The goal is to obtain a report that has not been fast-tracked and that carefully examines such issues as air quality, traffic and noise,” said R. Bruce Tepper, a lawyer representing Citizens for Communities Preservations, which filed its lawsuit March 30 in Los Angeles Superior Court. “They need to do a new EIR.”

Semcken said he is still hoping for a negotiated settlement, at least with Walnut, claiming that it is the only city in the area that remains opposed to the project.

“We have scheduled a meeting in the next couple of weeks,” he said. “Hopefully they will see what Diamond Bar did and what we’re paying to mitigate. We’ve got an entire consensus in the region.”

Walnut officials could not be reached for comment.