The Duu River is heavily polluted through varied human activity along its course. Despite the potential health hazards that the pollution of water bodies has on aquatic lives and persons who use the water bodies, river pollution persists. Samples from four points Slipway Community, Rock Spring Valley Community, Jallah Town 1 and Jallah Town 2 communities were subjected to both physical and chemical tests. The study identified uncontrollable dumping of wastes, defecation and institutional failures as root causes of pollution of the Duu River. The main anthropogenic causes were identified as indiscriminate dumping of refuse, channeling of raw sewage, defecation, discharge of untreated effluents from clinics and households waste into the Duu River. Physical tests showed that the Duu River was polluted since its turbidity exceeded Liberia Water Quality Standard (LWQS) class II (?5 mg/l) for surface water. The Biological Oxygen Demand for water sampled at all stations was above 3 mg/l and exceeded the LWQS Class II for surface water, indicating that Duu River has low potential to support aquatic life such as fish. The Chemical Oxygen Demand in September at sites (S1, S3 and S4) was above 3-10 mg/l, also showed high level of pollution of Duu River and exceeded the LWQS Class II for surface water. The Oxygen Demand in September at all sites and December at S1 and S3 was below LWQS Class II (6-7 mg/l) for surface water, indicating the high growth of algae and high level of pollution. The phosphate at all sampling stations in September, December and February exceeded the LWQS Class II (?0.02 mg/l) for surface water, indicating the increasing in the growth of algae and large aquatic plants. The Hexavalent Chromium of Duu River in September at S4, December at S1, S2 and S4; and February at S1, S2 and S4 are all above the LWQS class II (?0.1 mg/l) for surface water. That indicated that Duu river is polluted with chromium wastes or chromium materials which was disposed and has leased into the river. The defecation and dumping of wastes into the river are on the increased among other human activities. On this note, building of toilet houses, providing of garbage cans, sanitizing citizens on how their activities can harm life in the river including themselves, timely collection of wastes and proper enforcement of laws were recommended.