This data release contains reference baselines for primarily open-ocean sandy beaches along the west coast of the United States (California, Oregon and Washington). The slopes were calculated while extracting shoreline position from lidar point cloud data collected between 2002 and 2011. The shoreline positions have been previously published, but the slopes have not. A reference baseline was defined and then evenly-spaced cross-shore beach transects were created. Then all data points within 1 meter of each transect were associated with each transect. Next, it was determined which points were one the foreshore, and then a linear regression was fit through the foreshore points. Beach slope was defined as the slope of the regression. Finally, the regression was evaluated at the elevation of Mean High Water (MHW) to yield the location of the shoreline. In some areas there was more than one lidar survey available; in these areas the slopes from each survey are provided. While most of the slopes are for sandy beaches, there is some slope data from rocky headlands and other steeper beaches. These data files (referenceLine_WestCoast.csv and referenceLine_WestCoast.shp) contain information about the reference baseline, the cross-shore transects, and the Mean High Water values used to estimate the shoreline. The accompanying data files (slopeData_WestCoast.csv and slopeData_WestCoast.shp) contain the slope data. The csv and shapefiles contain the same information, both file types are provided as a convenience to the user.