Auxiliary material for Paper 2011GL047718 A novel approach for direct estimation of fresh groundwater discharge to an estuary Neil K. Ganju Woods Hole Coastal and Marine Science Center, U.S. Geological Survey, Woods Hole, Massachusetts, USA Ganju, N. K. (2011), A novel approach for direct estimation of fresh groundwater discharge to an estuary, Geophys. Res. Lett., 38, L11402, doi:10.1029/2011GL047718. Introduction Auxiliary material contains three figures detailing the calibrations used to relate continuous index data to tidal-cycle cross-sectional data in Mashapaquit Creek, Massachusetts, USA, during the August 11, 2010 survey. The calibration for channel-average velocity is displayed in “2011gl047718-fs01.eps”. The relationship between water level and channel area is displayed in “2011gl047718-fs02.eps”. The calibration for channel-average salinity is displayed in “2011gl047718-fs03.eps”. 1. 2011gl047718-fs01.eps Flood and ebb tide index velocity calibrations relating center-channel velocity with channel-average velocity. Separate calibrations were required due to the varying hydrodynamics near the index velocity site. The ebb tide calibration was forced to asymptote at index velocities above -0.28 m/s. 2. 2011gl047718-fs02.eps Water level-area relationship for the survey transect. 3. 2011gl047718-fs03.eps Index salinity calibration relating depth-averaged, channel-edge salinity (index salinity) with channel-average salinity.