Streamflow at 9 watersheds (12-77 Hectares) within the Hubbard Brook Experimental Forest in New Hampshire, USA has been measured continuously from as early as 1955. Streams are gaged with V-notch weirs, in some cases in combination with rectangular San Dimas flumes, at the outlet of each watershed. Through 2012, stage heights were recorded by means of a mechanical spring-wound clock and pen on a strip-chart recorder. Beginning January 1, 2013, these analog chart recorders were replaced with digital sensors. Overlap with both measurement techniques occurred for several years at all weirs. Streamflow data were gathered by the Hubbard Brook Experimental Forest and contributed to the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.