Tributaries of Lagos lagoon at Oworonsoki and Ebute Meta, known for residential and commercial activities were studied to assess the impact of coastal activities on Lagos lagoon. The mean levels of some parameters at the activity points gave evidences of pollution in the studied areas. The mean values for dissolved oxygen was 2.09 mg/l and chemical oxygen demand was 267 mg/l at Oworonsoki, while at Ebute meta, mean values for same parameters at the activity points were 1.16 mg/l and 786.5 mg/l respectively. The results obtained confirmed that the leachates generated from the activities at the studied locations contributed to the levels of some of the water quality parameters in Lagos lagoon.