Serving some 880,000 ha along the Blue Nile in Sudan, the Gezira-Managil Irrigation Scheme has led to dramatic increases in occurrences of malaria, schistosomiasis, diarrhea, and other water-related diseases. This study uses Gezira-Managil as a case in point to draw the attention of project planners to the problem of disease control in irrigated areas. For schistosomiasis, the study recommends a six-point control plan of providing safe domestic water supplies, modifying human behavior through education, modifying snail habitats, implementing biological controls, applying molluscicides, and providing chemotherapy. In the Sudan, a program using most of these measures costs about $2.40 per capita per year. It is suggested that similar multifaceted programs, with appropriate modifications for different vectors, can be used to control and treat malaria and other water-related diseases. Health education, community participation, and sanitation facilities are key features; immunization and oral rehydration therapy can also play important roles. In the Sudan, an integrated program to control all major irrigation-related diseases costs $6.00 per capita per annum. These costs, it is concluded, represent only a small percentage of total irrigation infrastructure costs, but are likely to yield a high return on investment in terms of increased human productivity and well-being. Includes a 2-page bibliography (1973-88).