These data describe longitudinal (upstream to downstream) patterns of dewatering during summer baseflow (July-September) conditions in nine watersheds in Shenandoah National park. In July-August of 2016 all nine watersheds (Jeremy's Run, Hazel River, Piney River, Hughes River, Staunton River, Whiteoak Canyon Run, Paine Run, Meadow Run, and Big Run) were evaluated for dewatering. In September of 2019, dewatering surveys were repeated in three watersheds (Pine Run, Piney River, and Staunton River) to evaluate annual variation in dewatering patterns. Data were collected by team of investigators walking each stream from an upstream point defined by the point along the stream draining 75-hectares (determined using watershed tools in ArcGIS Pro, version 2.6.0) to the bottom of each watershed near the park boundary, and mapping transition points between three hydrologic categories: Wet, dry, or isolated pools based upon investigator observation. “Wet” segments were defined as reaches where entire channel was wet with flow between pools; “Dry” segments were defined as reaches containing no water, or water of insufficient depth to sustain age 1+ brook trout; and “Isolated Pools” were defined as reaches containing pools of sufficient depth to hold 1+ brook trout but these pools were hydrologically disconnected from other parts of the channel. Because "Isolated Pool" type contains components of other two drying types (i.e., wet and dry), the boundaries were determined by the first transition/change encountered in the downstream direction of assessment. For example, when transitioning from a wet reach to isolated pools, the transition point marking the upstream boundary of the "isolated pool" would be the first dry segment encountered. Similarly, when transitioning from dry reach to isolated pool, the first encounter of a wet section would mark the upstream boundary of the isolated pool. Spatial coordinates of transition points were mapped using a Trimble R2 GNSS receiver for <1-meter accuracy.