It has come to the Seattle Police Department's attention that an unpermitted event is planned at either Green Lake or Magnuson Park on Saturday, June 24, 2017, which an estimated 1,500 people are expected to attend," the message on behalf of the police department from the parks department reds. "Based on the nature of this event, and what has occurred at similar past events, Seattle Police Department is concerned about the safety of both event participants and visitors to Green Lake and Magnuson Parks.