The Golden State Warriors face several serious obstacles in building a waterfront arena in San Francisco.

The Warriors targeted a 2017 opening date when announcing the project last year.

"I think the Warriors have underestimated how high the hurdles for a project like this would be," said David Lewis, executive director of Save the Bay, a regional organization that has worked to protect San Francisco Bay for the past 52 years.

The costs of repairs to Piers 30 and 32 are now pegged at $170 million, according to a city memo obtained by The Chronicle, up $50 million from what had been projected. 

The Warriors will release a third round of design in October as the project has changed engineering and design/architecture firms.

"There must," Lewis said, "be other places to build an arena."

Rick Welts, president of the Warriors, insists that the franchise is completely focused on the waterfront location beneath the Bay Bridge.