The Waterfront Summer Celebration on Sunday at Washington Harbour will include what’s being billed as the city’s largest water balloon battle at 2 p.m. For the family-friendly celebration, which will run from noon to 3 p.m., Washington Harbour restaurants will grill summer staples, including burgers, crab cake sandwiches and seafood. The event will also have a steel drum band, face painting, a balloon artist and other games and activities. Volunteers are still needed, and they’ll receive a Georgetown t-shirt and Starbucks gift card. To volunteer, email Meaghan Calnan: [email protected]. Betsy Woodruff