This manual provides background information and instructions on the use of a spreadsheet-based program for Bedload Assessment in Gravel-bed Streams (BAGS). The program implements six bed load transport equations developed specifically for gravel-bed rivers. Transport capacities are calculated on the basis of field measurements of channel geometry, reach-average slope, and bed material grain size. Calculations are carried out using Visual Basic for Applications (VBA), and the output is stored on individual spreadsheets. In addition to stepby- step instructions in software operation, the manual provides guidance in the interpretation of results.