Executive SummaryTegwane Ecological Services (Pty) Ltd was appointed to undertake a comprehensive aquatic biodiversity assessment of the freshwater ecosystems within the KwaMandlangampisi Protected Environment, located within the Dr Pixley Ka Isaka Seme and Mkhondo Local Municipalities of Mpumalanga Province. This assessment contributes to ongoing efforts to characterise and protect the ecological assets of a region that plays a critical role in maintaining both regional biodiversity and downstream water security.The purpose of the study was to develop an updated inventory of aquatic biota with a focus on freshwater macroinvertebrates, fish communities, and adult odonata. In addition, the assessment evaluated habitat integrity, geomorphological context, and water quality drivers that influence ecological patterns across the protected area. A wet season field survey was conducted from 23rd to 27th October 2025 and was supported by an extensive desktop review of national and provincial ecological datasets and planning frameworks.Aquatic ecosystems within the KwaMandlangampisi Protected Environment were found to be in a largely natural condition. Macroinvertebrate communities reflected high ecological integrity, with SASS5 scores and ASPT values representative of natural to largely natural systems typical of the Eastern Escarpment Mountain region. A total of forty nine taxa were recorded at SASS5 level. Among these, a potentially undescribed species belonging to the Leptophlebiidae (Aprionyx sp. nov.) was observed. This highlights the scientific importance of the area as a refuge for unique and potentially endemic aquatic taxa.Fish communities were consistent with expectations for the Southern Temperate Highveld ecoregion. Six indigenous species were recorded, with the assemblage dominated by Cyprinidae. One species of conservation concern, Labeobarbus nelspruitensis, listed as Near Threatened, was confirmed at multiple sites. No alien fish species were detected.Habitat assessments indicated high structural diversity and intact channel morphology. The sampled rivers ranged from steep mountain headwater streams to upper foothill transitional zones, with sinuous channels, riffle and pool sequences, and coarse bedrock and cobble substrates. Although localised pressures were recorded, including bank erosion related to livestock access and minor disturbance at low water crossings, these impacts were limited in extent and did not significantly alter the overall ecological integrity of the systems.Water quality remained within natural reference ranges for high altitude mountain systems. Electrical conductivity values were low, pH values were circumneutral to slightly alkaline, and dissolved oxygen concentrations were sufficient to support sensitive aquatic biota. No indicators of nutrient enrichment or other pollution pressures were observed.The KwaMandlangampisi Protected Environment overlaps with several high value freshwater conservation designations. These include Freshwater Ecosystem Priority Areas, Ecological Support Areas within the Mpumalanga Biodiversity Sector Plan, and the Enkangala Grassland Strategic Water Source Area. The Ntombe River is classified as Least Concern and moderately protected, indicating that the system retains high biodiversity value that is dependent on continued careful management. Collectively, these designations emphasise the significance of maintaining the ecological condition of the Sibandlu, Ntombe and Nkipane rivers.The freshwater ecosystems of the KwaMandlangampisi Protected Environment support high quality aquatic habitat, natural water quality, and biodiverse macroinvertebrate and fish communities. The presence of a potentially novel macroinvertebrate species and a Near Threatened fish species further elevates the conservation importance of the area. Continued protection of riparian corridors, management of localised erosion, and follow up surveys targeting Ephemeroptera diversity are recommended to strengthen the biodiversity baseline and inform long term ecological management within the protected area.