The Rio Declaration on Environment and Development, Agenda 21 and the Statement of Principles for the Sustainable Management of forests were adopted by more than 178 governments at the United Nations Conference on Environment and Development held in Rio de Janeiro in 1992. Protection of the quality and supply of freshwater resources, and the application of integrated approaches to the development, management and development, are specifically dealt with in chapter 18 of Agenda 21. Being a global initiative, South Africa's own approach towards protection of our freshwater resources, is therefore guided by Agenda 21. Management of freshwater resources needs to allow for sustainable utilization, whilst providing for their protection. Protection principles are contained in Chapter 3 of the country's National Water Act (Act 36 of 1998). The Reserve, the Classification System and Resource Quality Objectives (RQO'S) are protection - based measures that together form the Resource Directed Measures (RDM). These measures are in various stages of development and implementation. The Department Water Affairs and Forestry is confronted by many constraints and challenges: the infinite nature of water resources; linking policy with research and development; applying scientific Reserve methods to rivers with highly variable characteristics, as well as various operational constraints. The abovementioned water legislation also requires that all significant water resources in South Africa be classified to determine die quantity and quality of water reserved for ecosystem functioning, and to ensure that they are maintained in a minimum state of health related to an acceptable level of functioning. This paper presents an outline of RDM, with an emphasis on the need for and development of a national water resource classification system (NWRCS). Further, it highlights a proposed framework approach for the development of a NWRCS underpinned by principles used for developing such a system.