Evaluation of the current water quality of Lake Hawassa, Ethiopia

Abstract

The research aimed to evaluate the current wáter quality of Lake Hawassa in order to identify potential pollution sources and suggest appropriate measures. Physico-chemical water quality parameters have been determined by taking duplicate samples from seven sampling sites and the results were compared with WHO and FAO standards. The findings of the study revealed that the concentration of metals such as manganese (0.83 mg/L), zinc (5.75 mg/L), chromium (0.22 mg/L), phosphate (1.31 mg/L), and biochemical oxygen demand 5 (BOD5, 68.7 mg/L) exceeded WHO standard that could be due to point sources pollution from ceramics, textile, plastics, leather tanning and food processing industries located near the rivers and streams that end up into the lake. Moreover, the study indicated that the lake has also been polluted by non-point source pollution caused by urban stormwater, agricultural runoff, over grazing, deforestation, soil erosion and land development as it was shown with elevated levels of total dissolved solids (TDS, 928.3 mg/L), electrical conductivity (EC, 1851.4 μS/cm), turbidity (47.9 NTUs), fluoride (15.3 mg/L) and potassium (74.2 mg/L). Therefore, intervention measures should be put in place to prevent pollution of the lake.

Metabarcoding Analyses of Gut Microbiota of Nile Tilapia (Oreochromis niloticus) from Lake Awassa and Lake Chamo, Ethiopia

“…Fish from Lake Awassa showed lower microbial diversity than fish from Lake Chamo, which might be due to high pollution load from the municipality, regional hospital and factories surrounding the lake [ 40 ]. A recent study conducted on the water quality status of Lake Awassa reported that the concentration of metals such as manganese (0.83 mg/L), zinc (5.75 mg/L), chromium (0.22 mg/L), phosphate (1.31 mg/L) and biochemical oxygen demand 5 (BOD5, 68.7 mg/L) exceeded the WHO standard [ 21 ]. The effect of pollutants and toxins present in the environment on gut microbiota of fish was reported by several authors [ 41 , 42 ].…”

“…The maximum depth of the lake is 22 m. Its average pH is 8.17. The lake has an average temperature of 24.5 °C and its dissolved oxygen, total dissolved solid, nitrate and sulfate values of the lake water are 5.48, 974.5, 3.86 and 119.7 mg/L, respectively [ 21 ]. Lake Chamo is found in southern Ethiopia, and it is located in the Great Rift Valley at an elevation of 1235 m (a.s.l).…”

“…Lake Awassa is the prominent freshwater lake located in the central Ethiopian Rift Valley at the highest topographic position. It is near the city of Awassa, and has long been exposed to anthropogenic impacts, including over-fishing, irrigation, deforestation, overgrazing and indiscriminate use of pesticides and fertilizers in the catchment areas [ 21 ]. Several varieties of fishes are found in the lake of which the native African species, Nile tilapia ( O. niloticus ) is the dominant [ 22 ].…”

Assessing the Water Quality of Lake Hawassa Ethiopia—Trophic State and Suitability for Anthropogenic Uses—Applying Common Water Quality Indices

“…In addition, Hawassa Industrial park and the Referral hospital are releasing their effluents directly to the lake. This is a danger to the people that depend on rivers, streams and lake for domestic and other uses and to the existence of marine species [9].…”

Comparative Assessment of the Water Quality Deterioration of Ethiopian Rift Lakes: The Case of Lakes Ziway and Hawassa

“…In Table 1, it can be observed that the values EC for both lakes are increasing, furthermore, a study conducted by Teklu et at. [19], the maximum EC value for Ziway lake was streteched to 1740µS/cm , the recent study conducted by Zigide and Tsegaye [20] the maximum value for Hawassa lake has been extended to 1999.4 µS/cm. Both lakes have shown the dramatic changes and exceeding the maximum permissible limit of 1000 µS/cm [17,18].…”