The paper considers the several beneficial (provision of drinking water, fish, waste assimilation) and detrimental (overabundant plant life, habitat for pathogens and disease vectors) roles of the aquatic biota in general, before describing the use of the biota in river management through biomonitoring. This is followed by a description of a biomonitoring method called SASS which is based on the aquatic macro-invertebrate community. Results of using SASS4 are presented and show that SASS4 scores vary following water quality. SASS4 results are less expensive than the chemical analysis of water samples and represent water quality variation over a period of time. SASS4 has a role to play in the monitoring and assessment of water quality. It can be used as a substitute for chemical analysis in broad scale monitoring and allow chemical resources to be focused on sampling points where there would appear to be real water quality problems. Since river quality (both chemical and biological) reflects the manner in which the basin is managed, SASS4 provides key information pertinent to the management of river basins. It is concluded that river assessment based on the aquatic biota has an essential role to play in the management of river basins for sustainable utilization.