Water quality and supply are central to the socio-economic development of any nation. Scarcity of potable water results in the construction of dams and water treatment plants. Unfortunately, provision of potable water through improvement and treatment may prove to be difficult because of the socio-economic activities around a dam. This study is aimed at assessing the socio-economic activities around the Alau Dam Maiduguri, and how they affect the quality of raw water supply to Maiduguri Water Treatment Plant. The data was generated through the administration of questionnaires, and by interview and water quality analysis of dam and irrigation sites. The samples were subjected to physical, chemical and biological analysis to assess the impact of socio economic activities on the dam water, and its suitabilityfor drinking and agricultural uses. Findings reveal pollution with high concentration of nitrate (260–230 mg-NO3/l), phosphate (22–28 mg/l) and Escherichia coli (13–24 n/100 mg). This arose from improper sanitary management, inadequate public education on irrigation,indiscriminate waste disposaland some farming practices. Regular monitoring of socio-economic activities around the dam, and doing away with unhealthy waste disposal practices are recommended to safeguard the raw water supply to the treatment plant.