At the opening festivities of environment-themed Expo ’74, officials released 1,974 trout into the Spokane River to prove it could support fish life. Forty years later, Earth Day Spokane is returning to Riverfront Park in commemoration of the Expo ’74 anniversary. This time, no fish are required to participate — but the popular Procession of the Species returns at noon for those who want to dress up as their favorite animals, and the rest of the day will be filled with live music, Spokane Aerial performances, demonstrations and other activities to celebrate and appreciate this planet we live on.