Wastewater treatment is an imperative environmental challenge facing Mumias Sugar Company in Kenya. The company releases wastewater with inconsistent loading levels into River Nzoia. Findings from this study indicated that mean values for five parameters; pH, BOD5, COD ,TDS, and TSS all were above both NEMA and WHO standards for effluent discharge into the environment. Wastewater through the by-pass is discharged at relatively high velocity into the river and no pollution parameter loading is monitored. The study also revealed that four parameters; temperature, BOD5, COD, and TSS mean pollution levels through the line were above the recommended guidelines. Therefore, wastewater treatment system by Mumias Sugar Company was unable to reduce the quantity of chemical species responsible in increasing pollution loading due to the study parameters in the company effluent. Cumulatively, loading in the wastewater at the discharge points is significant and hence can be detrimental to the receiving environment. As a result, pollution loads recorded in the wastewater suggests that extremely high removal efficiencies will have to be achieved for standards compliance.