On Dec. 14, noon to 3 p.m., volunteers will help the Anacostia Watershed Society (AWS) sort trash removed from their River Terrace Trash Trap. They will sort it into 13 categories, count the pieces and measure the weight and volume of each category. The data collected is used to educate the public education and environmental advocacy. Learn about the trash challenges of the Anacostia and what is being done to address them. Volunteers meet at Bostwick House, 3901 48th St., Bladensburg, MD. anacostiaws.org.