ASSESSMENT OF SURFACE WATER QUALITY OF ERO DAM FOR IRRIGATION PURPOSE

The physicochemical parameters of surface water surface of Ero Dam for irrigation were assessed. Water samples were selected from three locations (upstream, downstream and control). Tested parameters for water samples are pH, electrical conductivity (EC), total dissolved solids (TDS), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), chloride (Cl-), carbonate (C03-), bicarbonate (HC03-), boron (B), sulphate (S042-), nitrate (NO3-N) and phosphate (PO4-P). The samples were determined in accordance with the American Public Health Association standards. Data were analysed using descriptive statistics. Evaluation of surface water quality of Ero Dam was carried out using different irrigation indices methods such as sodium adsorption ratio (SAR), residual sodium carbonate (RSC), sodium percentage (Na %), potential salinity (PS), The Soluble sodium percentage  (SSP), Kelly ratio (KR), magnesium adsorption ratio (MAR) and permeability index (PI) and compared with standard limits. The findings indicated that the concentrations of the Ca2+,  Mg2+, Na+, K+, Cl-, C03-, HC03-, B, S042-, NO3-N and PO4-P were within the acceptance limits for irrigation purposes except K+ that above the limits specified. Results indicated that majority, 87.5% of irrigation indices fall under excellent or suitable and classified as salinity (C1) and SAR (S1) which was known as (CISI). Hence, there are none degree of restriction in the application Ero Dam water quality for irrigation. Therefore, the results were concluded, that the study area surface water quality was suitable for irrigation.