This study examined the effects of glacier cover on summer streamflow across British Columbia, Canada, by applying nonparametric tests to assess trends in August discharge. Field-significant negative streamflow trends were found for glacierized catchments but not for those lacking glaciers. Effects of interannual climatic variations were accounted for by regressing August streamflow against August temperature and precipitation and July streamflow (to account for carryover storage). Trend analyses of the regression residuals suggested first-order stationarity for unglacierized basins, but revealed widespread negative trends for glacier-fed rivers, particularly from 1976 to 1996, consistent with the effects of glacier retreat.