The Effects of Uncontrolled Floricultural Farm Activity on Surface Water Quality: Case Study, Dembal Lake, Batu Ethiopia.

Abstract

The uncontrolled anthropogenic activities have been a serious treat for Surface water quality in developing countries. Floriculture industry is a booming sector in Ethiopia and is spreading throughout the country. The release of hazardous chemicals in the form of fertilizers, pesticides and disposal of untreated wastes which contaminates the water body. Dembal Lake is one of a few fresh water bodies among the Central Rift Valley Lakes. Its economic importance is significantly increasing from time to time. It serves as a fishery resource, small scale and large scale irrigation water supply, drinking water supply for Batu City, and many other uses. Dembal Lake in Batu city has been a discharge point of effluent from surrounded floriculture farms.  This study was carried out to evaluate the effects of uncontrolled floricultural farm activity on the surface water quality of the Lake. About five sites were chosen purposively from various points such as upstream, middle stream, lower stream and pristine lake environment.  The pristine site which was selected at the upstream was used as a control. A total of 45 samples were tested for physico-chemical, oxygen demanding, and nutrient parameters. The results were analyzed using SPSS and excel software to see if there were significant differences between the control and other sampling sites. EC, TDS, BOD, COD, NO₃^-, and PO₄^3- showed significant difference (P<0.05) between the control and other sampling sites. The result showed an increasing trends of TDS (350.1 ± 83.5 to 570.7 ± 175.5), EC (0.65 ± 0.045 to 2.24 ± 0.3), PH (8.7 ± 0.22 to 8.9 ± 0.5), and COD (96.4 ± 3.5 to 127.5 ± 6.34), BOD (17.3 ± 1.16 to 23.34 ± 7.52), NO₃^- (2.88 ± 2.35 to 52.5 ± 19.35) and PO₄^3-(0.8 ± 0.521 to 7.0 ± 3.512, respectively. The higher pollutant load that was observed along the downstream confirms the impact of floriculture activity. In addition, the result of physiochemical parameter also compared with WHO, FAO, and US-EPA Water quality guideline and the sources of pollution was also classified. Therefore the result of most water quality parameters were beyond the permissible limits of WHO, FAO and US-EPA water quality guideline values for use as a raw public water supply, irrigation, maintenance of fisheries and aquatic life respectively. So, proper floriculture wastewater management system and integrated pest management system are suggested.