Assessment of the Impact of Urban Runoff from Migori Town on the Concentration Levels of Selected Heavy Metals in Migori River, Kenya

Abstract

Water pollution and decreasing water quality is a major threat to water resources in urban set ups in the developing world. The key culprits include; agricultural runoff, untreated industrial and domestic wastewater, storm water and urban runoff. Migori is a rapidly growing city in Kenya with various land uses including crop and animal farming, industries, municipal markets, and commercial and residential set ups. The large volumes of urban runoffs generated in the town and its environs wash large pollutant loads into Migori River which is the main source of water in the region. This study investigated the effect of urban runoff from Migori town and its environs on the water quality of Migori River in terms of selected heavy metals. Water samples were collected from six established sampling stations along the river for six months (in wet and dry seasons). The water quality values were summarized as mean ± SE. Results indicated continued adverse impacts on the water quality of Migori River by urban runoffs. Water quality impairment in the river increased downstream – towards the town. Lead and nickel concentration levels are way above the WHO recommended guidelines for surface waters. Thus the river water poses serious risks to humans, animals and aquatic life. There is need for public awareness regarding the pollution problems and the consequences arising thereof in Migori River. There is also need for a study cataloguing the different chemicals used by different factories within Migori town. This will hopefully establish the definite sources of the heavy metals and nutrients and control their concentrations before they become too high and harmful to the ecosystem