Bob Vickers, Chairman of the Fairfax County Tree Commission, will lead a tree walk—in conjunction with the Great Falls Citizens Association—on Saturday, May 20 at 10 a.m. at Riverbend Park on Jeffery Road in Great Falls. Residents, including children, interested in learning more about prominent tree species that line the Potomac River should meet at the park Visitors Center and plan on a walk lasting approximately 1.5 hours. Nesting bald eagles may be visible during the walk. Wear appropriate clothing for the weather and sturdy shoes; the walk will be rescheduled if rain is in the forecast.