ASSESSMENT OF SURFACE WATER QUALITY USING PHYSICO- CHEMICAL AND BIOMONITORING APPROACHES. A CASE STUDY OF LIKANGALA RIVER, ZOMBA MUNICIPALITY.

The study was conducted to determine the water quality of Likangala River using biomonitoring and physico-chemical approaches. Experiments and direct field observations were applied. In order to do the study, water samples collected in three sites in triplicates were analyzed for various water quality variables such as pH, Temperature and DO on site whereas TDS, Turbidity, ORP, EC, Ammonia and Nitrates, TC and FC in the laboratory.
Statistical analysis such as trend analysis, Single factor Analysis of Variance (ANOVA) and Pearson correlation were performed using MS Excel analytical tool. WQI was computed for each site using an online WQI calculator. The results indicated that pH, DO, temperature, turbidity, ammonia and nitrates values were within the acceptable limits of different regional and international standards for surface waters in all site.
While some variables surpassed the permissible limits. Besides, correlation analysis showed a significantly strong and weak positive and negative correlation between some variables. The ANOVA revealed that there was a statistical significance of the observed difference (p<0.05) in physicochemical and microbiological water quality parameters. The WQI showed that the water quality was medium and unfit for some human purposes and fit for aquatic animals’ survival in all sites except downstream.
In biomonitoring assessment, collected samples of benthic environments (vegetation, stone or rocky and GSM) were poured into the white trays and macro invertebrate organisms in each site were identified using the SASS booklet of organisms. The sensitivity scores of organisms were obtained from the miniSASS sensitivity score sheet and the average sensitivity score of each site was computed and compared to the ecological category. In upstream and middle stream the average scores were within the range of 6.2 to 7.2 of rocky river category which indicated good condition whereas downstream was <5.3 which indicated very poor condition of river. The study reflects a medium water quality of water in the river. The results point out the need to take necessary steps before discharging the wastewater into the river and future policies by the responsive authority should be revised and re-enforced in terms of development of the environmental pollution control.

In order to do the study, water samples collected in three sites in triplicates were analyzed for various water quality variables such as pH, Temperature and DO on site whereas TDS, Turbidity, ORP, EC, Ammonia and Nitrates, TC and FC in the laboratory. In biomonitoring assessment, collected samples of benthic environments (vegetation, stone or rocky and GSM) were poured into the white trays and macro invertebrate organisms in each site were identified using the SASS booklet of organisms. In upstream and middle stream the average scores were within the range of 6.2 to 7.2 of rocky river category which indicated good condition whereas downstream was <5.3 which indicated very poor condition of river. The results point out the need to take necessary steps before discharging the wastewater into the river and future policies by the responsive authority should be revised and re-enforced in terms of development of the environmental pollution control.

The study was conducted in the vicinity of Zomba municipality surrounding Likangala River. The upstream region is Kalimbuka located at an elevation of 1015.52 m asl and middle stream is Namalaka at an elevation of 892.26 m asl and the downstream is Mpondabwino at an elevation of 812.35 m asl.

Traditional authority: Zomba City

District: Zomba

Coordinates: -15.3933, 35.32455