Assessing water quality by ratio of the number of dominant bacterium species between surface/subsurface sediments in Haihe River Basin

•Comprehensive quality of water was assessed by using Gaverage based on the concentrations of different pollutants.•Pollutant concentrations of water in Haihe River higher than those in discharge of municipal wastewater treatment plants.•Using the modified PCR–DGGE method, 162 dominant bacterial species were identified.•The ratio of dominant bacterium species between surface sediment and subsurface sediment can reflect water quality.