In 1988 a research program for the ecological rehabilitation of the river Rhine was started. In this research program three Dutch governmental institutes are working together: the Institute for Inland Water Management and Waste Water Treatment (D.B.W/RIZA), the National Institute for Public Health and Environmental Protection (RTVM) and the Netherlands Institute for Fishery Investigations (RTVO). The research program covers the period 1988-1991 and amounts to 20 manyears per year