Analysis of Total Maximum Daily Loads of Winongo River, Special Region of Yogyakarta, Using Water Quality Analysis Simulation Program (WASP)

Abstract A total maximum daily load (TMDL) is the amount of a pollutant load that a waterbody can accommodate without exceeding the water quality standard for that particular pollutant. The research aimed to measure pollutant loads in the Winongo River, TMDLs, and pollutant reduction needed if pollutant loads were higher than TMDLs. The Water Quality Analysis Simulation Program (WASP) model was used to determine water quality responses to the potential amounts of pollutants discharged into the river, resulting in information on existing pollutant loads. After testing the water quality parameters, it was found that pH and BOD at points 2–7 and TDS at all the sampling points meet the standards for Class 1 water per the Governor Regulation No. 20 of 2008. The WASP model showed a total pollutant load of 51,78 kg/day and a TMDL of 139,08 kg/day. Segment 1 had the lowest pollutant load of 2.57 kg/day, then the TMDL was 4.56 kg/day. The highest pollutant load measured was found in segment 6 of 20.11 kg/day, then the TMDL was 79.13 kg/day. Based on the results, the Winongo River can accommodate the pollutant loads while maintaining the water quality.