Protecting the health of swimmers who use surface waters for recreation has been of interest to public health officials in the United States since 1930. It was well recognized at that early date that human excreta discharged to surface waters posed a health hazard to those who used the water for recreation. Although the relationship between swimming-associated health effects and feces-contaminated water used for swimming had not been defined, microbial limits based on coliform bacteria were used in many states, particularly when there was physical evidence of sewage contamination. The limiting values selected by responsible authorities were based more on attainment rather than on risk of illness. Thus, there was little uniformity among states regarding what level of coliforms constitute waters safe for swimming. Several states chose 1,000 coliforms per 100 ml as a measure of good quality water, but there was not much uniformity among states regarding what level of coliforms was a safe level. There was, however, a general understanding that fecal contamination of surface water posed a risk to those exposed to the water, and that the risk might be limited by setting a level of fecal contamination above which exposure would be unacceptable. The manner in which water samples were taken, the frequency of sampling, and the number of samples were usually not described in the early literature.