During the summer of 1939 the state of Michigan provided for an extensive survey of the distribution of schistosome dermatitis and for experimental work on control measures. The survey was conducted by a field party consisting of two zoologists, a chemist, and two assistants. A well-equipped laboratory truck, a boat and various other items were placed at their disposal. The University of Michigan Biological Station, located in the center of the area affected by water itch, offered its facilities to the group; it made an ideal point from which to carry out the investigation. The primary object of the study was to find beaches, preferably public beaches or those of boys’ and girls’ camps, where the water itch was prevalent and to discover a method that was simple to use, effective, and inexpensive. During this experimental stage all the expense was borne by the state. A total of 139 beaches were examined, and 25, on ten different lakes, were treated with chemicals. The beaches treated comprised only a small portion of the total lake area. The size of these beach areas varied from 15,000 to 360,000 square feet. Quantitative analyses were made for carbonates, becarbonates, pH, and copper both before and after treatments. Considerable variation was observed in the composition of the lakes examined, the pH varying from 7.8 to 9.0, carbonates from 0 to 20 p.p.m., and bicarbonates from 58 to 160 p.p.m. For a given lake the pH was found to be fairly constant; the carbonates and bicarbonates varied considerably in widely separated areas of the same lake. The organic content of the lakes varied widely, but no quantitative determination was made. Currents, produced by weather conditions, were much more rapid than had been anticipated; in some cases the drifts were as great as 200 to 400 feet per hour. During the summer of 1940 the work was carried on by three men who examined beaches, recommended methods of control and supervised the measures taken; the chemicals and labor were supplied by individuals or local organizations. About 250 beaches on sixty different lakes were examined, and some 61 received chemical treatment. Observations were confined to the effect on the snails; no chemical analyses were made. The advice concerning control measures was based on the work of the previous year and on the experience of other specialists in this field. Many and varied methods have been advocated for the control of water itch. All can be placed in one or the other of two main categories: the prophylactic measures to be taken by the bather, or the chemical treatment of bathing areas to eliminate the cercariae of their snail hosts.