Macrobenthos are important bioindicators of organic and nutrient pollution. The present study used the macrobenthos-based rapid bioassessment protocol (RBP II) to study the effects of treated textile effluent inputs into a natural stream ecosystem connected to a wetland marsh. Three reference sites and three sites receiving point How to cite this article: Wijeyaratne, W. M. D. N., & Liyanage, U. P.. (2021). Macrobenthos-based RBP II (Rapid Bioassessment Protocol II) as a tool to assess the sediment and water quality in a treated textile effluent receiving stream ecosystem associated with a wetland marsh: A case