Baseline assessment of water quality along Nakulabye stream

Abstract

Nakulabye stream, a natural resource within the Nakulabye catchment, serves as a habitat for some aquatic organisms. It also serves as a source of drinking water for livestock and used for agricultural purposes such as irrigation. As a result of increase in human settlements and economic activities along the stream and constant discharge of effluents into the stream, the variation of water quality along the stream was assessed. Also, the land use activities in Nakulabye stream catchment were documented. Water samples were collected from 5 sampling sites; site 1 (upstream and control), site 2 (upstream), site 3 (midstream and a major tributary), site 4 (midstream and a major tributary), site 5(downstream and outlet) and analysed for pH, electrical conductivity (EC), temperature, total dissolved salts (TDS), total nitrogen (TN), total phosphorus (TP) and chemical oxygen demand (COD). Electrical conductivity (EC) was highest at site 2 with a mean value of 7.8±0.3 ms/cm and lowest at site 3 with a mean value of 4.4±0.1 ms/cm. Total dissolved solids (TDS) concentration was highest at site 2 with a mean value of 3.9±0.3 mg/l and lowest at site 3 with a mean value of 2.2±0.1 mg/l. pH was highest at site 2 with a mean value of 7.8±1.5 and lowest at site 1 with mean value of 5.8±1.2. Temperature was highest at site 2 with a mean value of 26.5±1.6 oC and lowest at site 1 with mean value of 25.2±1.2 oC. Total phosphorus (TP) concentration was highest at site 2 with a mean value of 1.8±0.3 mg/l and lowest at site 1 with a mean value of 0.4±0.1 mg/l. Total nitrogen (TN) was highest at site 2 with a mean value of 16.7±0.8 mg/l and lowest in site 1 with a mean value of 2.7±0.6 mg/l. Chemical Oxygen Demand (COD) was highest at site 2 with a mean value of 82.7±0.3 mg/l and lowest at site 1 with a mean value of 16.3±0.1 mg/l. This study showed that water quality parameters such as COD (p=0.00), TDS (p=0.00) and EC (p=0.00) varied significantly along the stream. In general higher values were recorded at site 2 (upstream) and the lower values were recorded at site 3 (midstream). Land use activities at site 2, that might be contributing to the observed pollution are garages, farmlands, schools, churches, hostels, dumping sites and washing bays. From the findings of this study, it is highly recommended that further studies be carried out on the minor tributaries such as water channels from houses and restaurants, along Nakulabye stream to assess their impact on the stream, since this study focused mainly on the major tributaries