The letter said Hughston had made conflicting statements about the expected crowd size and security preparations, on-site medical facilities and other matters.
"Given the ongoing uncertainty about basic safety elements of your plan and your unfortunate pattern of deception and misrepresentation about your planning efforts, we cannot put the public at risk and grant a permit for your proposed event," said the letter dated Tuesday and signed by Diane Rea, the department's manager of permits and reservations. The San Francisco Chronicle first reported the permit denial.
Hughston called the letter a "character assassination," saying he has a flawless record as a concert promoter and had organized events at Golden Gate Park and elsewhere since the 1970s without any problems.
He said the parks and recreation department had given him permission 2 weeks ago to advertise the event but was now searching for ways to back out and cancel the event and had fabricated what they called misrepresentations.
"They're going after my credibility, saying I lied to them which is totally untrue," Hughston said in a telephone interview.
He plans to file an appeal against the permit denial this week and said he still hopes the event can take place.
He said he'd already lined up about two dozen performers for the concert including the remnants of Jefferson Airplane, Janis Joplin's Big Brother and the Holding Company and the Santana Blues Band. The free concert was scheduled to take place in the Polo Field at Golden Gate Park.
"The Summer of Love all started in the Polo Field in San Francisco. This event celebrates that whole movement," Hughston said. "To cancel this event is like slapping San Francisco in the face, and the rest of the world for that matter."