Development of health effects criteria for fresh water bathing beaches by use of microbial indicators.

This was accomplished by contacting family groups at the beaches on weekends and obtaining information on bathing activity by the use of interviewers. These beachgoers were questioned by telephone 8-10 days later concerning health related symptoms.An epidemiological-microbiological study was conducted at Lake Keystone, Oklahoma, near Tulsa, Oklahoma, to help develop recreational water quality criteria based upon health effects. Symptomatology rates among swimmers relative to non-swimmer controls were examined at a "barely acceptable" (BA) beach, Salt Creek North (I), and Keystone Ramp (II), and a "relatively unpolluted" (RU) beach at Washington Irving South (III).Therefore, the objective of relating illness as measured by symptomatology to an indicator of water quality has been addressed.Measurements were made for a number of potential microbial indicators of pollution during the time the interviews were being made. When the data from the BA and RU beaches was examined, the symptom rates categorized as gastrointestinal, respiratory and "other" were higher among swimmers than non-swimmers. Although the data was not statistically significant, definite trends could be shown in that direction. Good agreement was obtained between geometric means of Escherichia coli and enterococcus densities and the differential (swimmers minus non-swimmers) rate of gastrointestinal symptoms