SURVEILLANCE OF MICROCYSTIN IN IOWA’S DRINKING WATER

From July of 2016 to June of 2017, most of Iowa’s surface water and influenced groundwater public water systems volunteered for a study to determine microcystin levels in both raw and finished (treated) water. The purpose of the study was to 1) determine the occurrence and levels of microcystin in raw source water, and 2) determine if each public system’s treatment process is effective in removal of the toxin. The project involved weekly collection of raw water sample by public water system staff and sample shipment from the system to the Iowa State Hygienic Laboratory where analysis was conducted for total microcystin using the ELISA method. Depending upon raw water microcystin levels, additional sampling was requested at the raw and finished water locations in the system at increased frequencies. Study findings indicate that microcystin was present in 11 of the 26 participating systems (42%), with detections most common during the months of September and October. The last raw water microcystin detection for 2016 was on December 27. The highest concentration of total microcystin in raw water exceeded 5 µg/l. There was no confirmed detection of total microcystin in finished water during this project.