A community cleanup event hosted by the Neponset River Watershed Association will be held on Earth Day, Sat., April 20, from 9 a.m. to noon. Volunteers can join teams to clean up at any of nine locations: Tenean Beach, Squantum Point in Quincy, Riverside Avenue in Milton, Edgewater Drive, Granite Avenue, the Neponset Greenway Canopy Walk, the Blake Estates Urban Wild in Hyde