The chemical hydrology of the River Oshun, Western State, Nigeria

Summary The changes in the chemistry of the waters of a small river before and immediately after it has been dammed are reported here. Pre‐impoundment investigations reveal the paucity of nutrient salts which became slightly more concentrated in the Ientic environment created after the closure of the dam. Also, the fluctuations in the chemistry of the waters were influenced by a number of physical factors notably water level, current velocity and temperature. Deoxygenation of the usually oxygen‐undersaturated river waters was not observed after the closure of the Asejire dam built across the River Oshun.