Previous assessment of the effect of land use changes on water quality of Eleyele lake Ibadan, Nigeria
revealed that pollutants are being washed by rainfall runoff into the lake which indicated the need for
further study. In this study, Universal Soil Loss Equation (USLE) was used to estimate the quantity of
soil that is being lost into the lake using parameters derived from an earlier study. The result revealed
that 2080 kg of soil is being washed into the lake annually. Tests to determine the water quality of the
two streams that flow into the lake and, the outflow were done. The results showed that between 6 and
95% of the pollutants washed into the lake were retained or converted to sediments which may cause
it to eutrophicate in the future. To compute water accounting for the lake watershed, precipitation over
the area was calculated, discharge measurements on the two rivers that empty into the lake and outflow
from the lake were done, and also, the evaporation/evapotranspiration were determined. The
results showed that 59% of the gross inflow was available for potable water supply while 30.3% of the
total outflow was uncommitted. Evapotranspiration (including lake surface evaporation), municipal/industrial
and total outflow were 1.0, 59 and 31% respectively. Management plan and useful recommendations
have been suggested to improve the reliability of the lake.