Assessment of water resources development impact and setting of minimum threshold in Uganda - River Nyamugasani Catchment

Abstract

The Ministry of Water and Environment (MWE) through the Directorate of Water Resources Management (DWRM) obtained funding from the United Nations Educational, Scientific and Cultural Organization (UNESCO) through the participation programme arrangement for 2020/2021 to carry out a water resources development assessment to determine the threshold for environmental flow in the Nyamugasani catchment, in order to address some issues of water governance in terms of planning, management and allocation. The main objective of the study was to assess the magnitude of downstream impacts of water resource development projects on flows and quality of water in Nyamugasani system and suggest probable ecological limits of water flows to minimise adverse or irreversible environmental effects while meeting the basic human social and economic requirements of both upstream and downstream communities The study was carried through literature review, stakeholders’ engagements, data collection and analysis, survey of the water systems profiles, discharge measurement, ecologic and water quality sampling as input to the models. The study findings show river/lake are used by over half (52%) of the population and is the most dominant source of water. The borehole used by 24% of the population is the second most important source. The rest of the population depend on protected springs (15%), open wells (7%) and a limited number (2%) on pipe water. The majority (64%) access their water sources over distances greater than 500m and 86% on average use less than one jerry can per person per day, which further indicates the difficulty of accessing water sources. It is estimated that the average water demand for livestock in the Nyamugasani catchment is 6531.4 litres/day or 0.08l/s. Over half (54%) of the households discharge grey water into the open areas, 40% into household gazetted disposal areas, while 6% into the drainage system. The survey findings further indicate that 60% of households dispose of solid waste into garbage pits, 9% into gazetted collection points while 30% into open areas and the majority of the households (92%) have toilet facilities. The physiochemical parameters of water quality were found to be within the acceptable standards (World Health Organisation Standards) however all the points along the river were found to have Microbial contamination with exception of only Kanyampara stream which had no contamination. The microbial contamination is mainly attributed to river bank encroachment by human settlements.