Nyagongo Ahmad AdamNdibalema Vedasto GabrielLalika Makarius Christian Sengilinga2026-02-022026-02-022025-12-30DOI:https:doi.org/10.56542/wi.jwempo.v2.i2.a13.2025https://www.suaire.sua.ac.tz/handle/20.500.14820/7274Journal of Water Resources, Engineering, Management and Policy, pp. 204-222The health of river ecosystems is increasingly threatened by human activities such as agriculture, urbanization, and industrialization. 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-bottom method and analyzed using the Shannon–Wiener diversity index and the Average Score Per Taxon (ASPT). Riparian vegetation was surveyed through belt transects and assessed by species distribution and proportional cover. Fourteen macroinvertebrate 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), indicating worsening water quality downstream. The riparian zone was heavily modified: about 58% grasses, 28% shrubs, and 14% trees, reflecting human disturbance and land-use change. The results reveal progressive ecosystem degradation along the river, strongest downstream, likely driven by pollution and catchment alteration. These results call for integrated catchment management policies, stricter land-use regulation, and community-based riparian restoration programs to enhance water quality, biodiversity, and long-term ecological resilience of the LRC.enEcological healthLukosi river CatchmentMacroinvertebratesRiparian vegetationBioindicatorsArticle