Protocol and guidelines for the Mini Stream Assessment Scoring System (miniSASS), a citizen science tool developed in South Africa for community-based river health assessment. miniSASS enables non-specialists to assess the impact of human activity on rivers by surveying populations of aquatic macroinvertebrates. How it works: participants collect macroinvertebrate samples from streams and rivers, an AI-powered smartphone app helps users identify invertebrates using a digital interactive visual identification key, the app calculates a miniSASS score, a machine learning algorithm independently verifies readings, and all measurements, photos, and data are uploaded to miniSASS.org. The Enviro-Champs initiative, started in Mpophomeni township (KwaZulu-Natal) under the Duzi-uMngeni Conservation Trust and GroundTruth, has grown to approximately 1,000 volunteers. miniSASS directly supports monitoring of SDG 6 indicators 6.3.2 (proportion of water bodies with good ambient quality) and 6.6.1 (change in extent of water-related ecosystems).