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Abstract—This study vitalized the uncertainty and fuzzy rules consideration in the estimation of phosphorus loadings and eutrophication status of the hydrologic system namely detention pond using Fuzzy Logic (MATLAB). These methods were chosen to cater for the uncertainty of loading factors such as sediment and phosphorus inflow, inflowing discharge and pond storage volume. The average of phosphorus concentrations obtained from site investigation was 0.178 mg/L, hydraulic residence time was 1.77 year and the average annual hydraulic loadings was 694.70 m/yr, obtained based on the 12 years period (2000-2012). The results showed that the maximum and minimum of phosphorus loadings was 2.00 x 10-3 ton/year and 5.00 x 10-3 ton/year. Phosphorus loadings obtained from MATLAB fuzzy logic was 3.9 x 10-3 ton/year. The eutrophication status of the detention pond was investigated using Fuzzy Logic Approach, incorporating various fuzzy rules (MATLAB). This evaluation required the twinning usage of Vollenweider P-Loadings diagram. Generally, eutrophication status in the detention pond at KolamTadahan UTM was still considered Oligotrophic stage. However precautions need to be established as the pond are alarmingly approaching the Eutrophic Status