Rollin' on the River returns to downtown Allegan this summer City of Allegan and last updated 2021-05-14 16:08:57-04 ALLEGAN, Mich. â Rollinâ on the River will return to downtown Allegan this summer, according to a news release Friday. The free summer concert series begins Friday, June 11 and continues for every week for 12 weeks until Friday, Aug. 27. City of Allegan Live music starts at 7 p.m. and continues for two hours. Past performers â including Asamu Johnson & The Associates of the Blues, Guitar Up! And Hollywood Makeout â will return this year, along with new bands like The Bootstrap Boys, Modern Adventures, The Hacky Turtles and more.