Potential Impacts of Oil and Grease on Algae, Invertebrates and Fish in the Bujagali Hydropower Project Area

Abstract

This study determined the concentration of oil and grease and inferred its impacts on algae, invertebrates and fish. Water samples were collected in April and September from 2012 to 2018 at the upstream and downstream transects and in the reservoir, and analysed for oil and grease following standard procedures. Environmental compliance was compared to NEMA’s discharge standard of 10 mg/l, and its PAH effluent discharge standard of ≤ 0.1 mg/l. At all sites, average concentrations of oil and grease were below 10 mg/l throughout the sampling period. Out of the 14 data sets for each transect, only 3 along the upstream transect, and 2 at each of the downstream transect and the reservoir were compliant with the effluent discharge standard. Although impacts of oil and grease on aquatic biota were not assessed, their relatively high concentration compared to total Polycyclic Aromatic Hydrocarbon (> 0.1 µg/l) is considered hazardous to most aquatic organisms. The diverse activities around the project area implied that sources of oil and grease were proportionately diverse. Hence, the observed trends may not solely be attributed to the hydropower project. Accordingly, assessment of the various sources of oil and grease and their impact on aquatic biota in the area is recommended.