By Andrew Ragas Bass anglers sometimes wonder why certain rivers of Wisconsin’s flowage belt fish best in spring and go unproductive in summer. Understanding the dynamics and little-studied stream migrations between river and reservoir smallmouth bass will help answer these questions. Throughout my evolvement as a northwoods bass angler, questions have emerged, often pertaining to the biology of certain fisheries and the movements of certain species. One that often arises is the question of fish migration, especially on the major river systems and their corresponding flowages scattered throughout the Northern and Central regions of Wisconsin. Ten years ago, when I began exploring this region and its many river miles for smallmouth bass, I never understood why some of my favorite pools and sections of the Wisconsin River were most productive during the months of May and June and then went dormant and nearly devoid of fish as the summer weeks progressed. Despite successfully floating and wading them for many miles, and regardless of the excellent habitat and locations I was fishing throughout the year, I could never understand why these stream smallmouth were in abundance