This dataset contains annual mean stream water flow/discharge data derived from daily means for headwater streams draining forested hillslopes measured at stream catchments C31, C32, C33, C34, C35, C37, C38, C39, C42, C46, C47, C49, and C50 in the Turkey Lakes Watershed, approximately 60 km northwest of Sault Ste. Marie, Ontario, Canada. This data set is recorded as annual mean flow by calendar year (January-December in litres per second), annual mean flow by water year (October to September in litres per second), and annual number of zero flow days by water year. Daily mean flows that were used to derive this data set were recorded from 1981-2012 by the Great Lakes Forestry Centre, and are reported for 1981-2011 due to some inaccuracies throughout the 2012 data. Hydrological gauging stations employ "flow-control" 120 degree V-notch weirs (catchments 31, 33, 34, 37, 39, 42, 46, and 47), 90 degree V-notch weirs (catchments 32, 35, and 49), and 60 degrees V-notch weirs (catchment 38) to facilitate monitoring of stream discharge. Water "stage" or depth within the structure (e.g. in the pool behind the weir notch) is automatically and continuously recorded by chart recorders (Leupold & Stevens A-71 SE Water Level Recorder) from 1981-2003. Capacitance rods (Trutrack WT-HR 1000) installed in stilling wells replaced the chart recorders over the period of 2002 to 2003 and were used until 2012. The capacitance rods logged data at 1 hour intervals for the majority of their use and then averaged to a daily rate. Manual stage measurements have been taken intermittently when synoptic water chemistry samples were taken throughout the years. Stage data are then converted to a continuous record of flow using the relationship between stage and discharge measurements.