The Riverbar Drawdown Shore natural community occurs in the “drawdown” zone—the narrow zone between high and low waterlines that occur in a typical year. In the Potomac and Shenandoah rivers in Harpers Ferry National Historical Park, this zone is usually underwater in winter and spring, and above water from summer to early fall. This natural community may initially develop on a very narrow strip of exposed shore. This zone can grow during dry periods, and shrink during wet periods. During wet years this community may develop higher on the bank; it’s normal habitat may remain underwater in the growing season.