Nyagongo Ahmad AdamNdibalema Vedasto GabrielLalika Makarius Christian Sengilinga2026-02-022026-02-022025-12-30https://www.suaire.sua.ac.tz/handle/20.500.14820/7270Journal of Water Resources, Engineering, Management and Policy, pp. 204-222The health of river ecosystems is increasingly threatened by human activities such as agriculture, urbanization, andindustrialization. This study evaluates the ecological status of the Lukosi River Catchment (LRC) in Kilolo District, Iringa, Tanzania, using macroinvertebrates and riparian vegetation as bioindicators. We employed a cross-sectional design, sampling at upstream, midstream, and downstream sites. Macroinvertebrates were collected via the kicking-bottommethodand analyzed using the Shannon–Wiener diversity index and the Average Score Per Taxon (ASPT). Riparian vegetationwas surveyed through belt transects and assessed by species distribution and proportional cover. Fourteenmacroinvertebrate taxa were identified, dominated by water scavenger beetles and snails. Biodiversity was moderate(H′ ≈1.98). ASPT scores declined spatially: upstream (good quality), midstream (moderate), and downstream(poor), indicatingworsening water quality downstream. The riparian zone was heavily modified: about 58% grasses, 28%shrubs, and14%trees, reflecting human disturbance and land-use change. The results reveal progressive ecosystemdegradationalongtheriver, strongest downstream, likely driven by pollution and catchment alteration. These results call for integratedcatchment management policies, stricter land-use regulation, and community-based riparian restoration programstoenhance water quality, biodiversity, and long-term ecological resilience of the LRC.enEcological healthLukosi river CatchmentMacroinvertebratesRiparian vegetationBioindicatorsArticle