Many volunteers, including Kirkland Mayor Joan McBride and Deputy Mayor Penny Sweet, planted more than 800 plants during an Arbor Day event at Juanita Bay Park on Nov. 12.
McBride also planted a tree.
Council members hope the increased presence of officials will deter break-ins at trailheads.
Both directions of traffic will be closed around the clock until June 4.
For those possibly exposed to measles between April 30 and May 3, the most likely time to become sick would be between May 7 and 24.