Trends in Swim Advisories
Number of Microcystin-Related Swim Advisories Issued at Iowa State Park Beaches
Microcystin-Related Advisories Issued Per Year
Since the Iowa Department of Natural Resources beach monitoring program began, the number of annual swim advisories issued for microcystin has increased dramatically.
Why is our 2019 annual microcystin advisory number different from the DNR's?
The DNR issues swim advisories for microcystin at the beginning of the week if samples are greater than the 20 microgram/L advisory threshold. During Week 12 and Week 13 of 2019, DNR took "endpoint" samples of beaches with microcystin advisories at the end of the week. As reported in emails from DNR dated Aug. 16 and Aug. 23, they found the endpoint sample was below 20 micrograms/L for three beaches and made the decision not to include those advisories in their final count for the summer. Therefore, the DNR reports only 21 microcystin advisories for 2019. However, IEC's final count reflects those three additional advisories because the advisories were issued by DNR and warning signs were put up at the beaches.
Number of E. coli-Related Swim Advisories Issued at Iowa State Park Beaches
E. coli-Related Advisories Issued Per Year
Overall, the number of annual E. coli-related swim advisories issued at Iowa State Park beaches has also trended downwards in the last six years.