SPRINGS AS A DOMESTIC WATER SOURCE IN SOUTHERN ETHIOPIA: WATER QUALITY AND PROVIDENCE

Less than 15 % of the rural population of the Southern Region in Ethiopia has potable water despite the paradox that the region is relatively humid. Sources for domestic water are commonly streams, puddles, and shallow wells. Water from natural, low yield springs (> 0.2 L/s) in highland areas is being protected and routed for domestic use. We report the study of protected/unprotected springs and rivers along a topographical gradient in the Lake Chamo and Lake Abaya drainage basin to assess spring water quality and providence. Samples were collected from elevations of 1180 to 2660 m.a.s.l. and analyzed for concentrations of major solutes, nutrients and the d¹⁸O and dD of water. We found that the water in most of the protected springs has a chemical composition similar to that of precipitation (TDS < ~15 mg/L), in contrast to deeper groundwater (TDS > ~250 mg/L). The spring waters probably discharge from short local flow systems. The local meteoric water line derived from the isotopic content of the dilute spring waters is dD=8.1 d¹⁸O + 19.0. Both dilute and deeper ground waters are potable, but some have concentrations of total dissolved nitrogen > 6 mg/L (as N) and phosphate > 0.2 mg/L (as PO₄). Although the nutrient levels are not a health risk, they do indicate agricultural contamination immediately up-gradient of the affected springs. Modest well-head protection, such as planting thorn bushes to inhibit livestock from entering the local recharge zone, is recommended and being implemented.