The quality of water in Haihe River was studied from 1993 to 1997. Results showed the river was heavily polluted, mainly by NH3-N, NO2-N, and organic contaminants. Over those years, the water quality improved but pollutant levels flowing into Bohai Bay increased before decreasing in 1997. The levels went up for CODMn, BOD, NH3-N, NO3-N, and NO2-N from 1993 to 1996, then dropped in 1997. This change may be due to alterations in the river's runoff.