From abstract: Results of a study of the sanitary engineering aspects of fallout from nuclear weapons are reported. Data were obtained from: a. Weekly surface water samples from 22 stations on streams and reservoirs in Eastern Massachusetts, collected from March, 1952 to July, 1953, and assayed for radioactivity. b. Weekly rain samples from March to July, 1953. c. Stream mud and soil samples collected before and after a large fallout. d. Results of fallout activity measurements by others based on samples from Massachusetts and the vicinity of Rochester, New York. Plots are presented showing the relations of the radiological data to the timing of detonations and the daily precipitation and showing daily deposition of activity and concentration in runoff. Runoff coefficients for fallout radioactivity are calculated.