From the EarthDay5k website:
The Shoreline, Earth Day 5k welcomes all runners, walkers, and kids to participate in our 5k and kids third of a mile fun run. At the end of the race each participant will receive a tree that they can bring home and plant. There will also be great prizes and lots of food for everyone at the end.
Link to EarthDay5k.org for more information and to register for the event