Riverside Mayor Bill Poch (right) conducts a Riverside City Council meeting at City Hall on Jan. 21. (Jim Slosiarek/The Gazette)When a 51,000 square-foot casino opened in Riverside, surging tax revenue created a windfall for the small southeast Iowa town, about a dozen miles south of Iowa City.The Riverside Casino and Golf Resort, which opened in 2006, quickly became a game changer for the community of 1,040 with little beyond a couple of gas stations and a bar and grill.