Monitoring at all 38 state park beaches began May 23 and will continue into September.
Beach water samples are compared to water quality standards to determine the risk of waterborne illnesses for swimmers. All state park beaches will be monitored at least once per week.
Iowans and visitors can find weekly results on the DNR website at www.iowadnr.gov
“Iowa has received above average rainfall over the past several summers, which has raised the number of advisories posted at some beaches in recent years,” said Jason McCurdy, coordinator for the DNR’s beach monitoring program. “In spite of this, monitoring over the past 11 swimming seasons has shown that our state park beaches are safe for swimming the majority of the time.”
Just as in 2005 through 2010, state park beaches will post a “swimming is not recommended” sign if:
·The geometric mean exceeds the water quality standard (the five most recent samples within a 30-day period exceeds 126 colony-forming units of E. coli bacteria per 100 milliliters of water)
· The beach has had bacteria problems in the past (causing it to be classified as a “vulnerable” or “transitional” beach) and one sample exceeds Iowa’s one-time maximum standard (235 colony-forming units of E. coli bacteria per 100 milliliters of water)
The DNR considers beaches “vulnerable” after more than two years of high geometric means within a five year period. They are no longer “vulnerable” when this condition no longer applies.
“Transitional” beaches include beaches where bacteria problems appear to have been resolved or no longer pose a serious threat. Beaches in this transitional class may be removed from this list if they do not exceed the geometric mean standard for one year.
The program will also monitor state-owned beaches for cyanotoxins, harmful substances produced by cyanobacteria, also called blue-green algae. Water samples will be tested for total microcystins, a widespread, commonly occurring group of cyanotoxins. Concentrations of these substances can become elevated during an algae bloom. Reports of health effects associated with cyanotoxin exposure are rare, but exposure can cause skin irritations and allergy- or asthma-like symptoms while ingestion of the toxin can lead to gastrointestinal discomfort, including vomiting and diarrhea. In the event that a sample exceeds the World Health Organization’s action threshold of 20 µg/L total microcystins, an advisory sign will be posted warning beachgoers that an increased potential for exposure to cyanotoxins exists.
Posting a swimming advisory does not close a beach. However, the DNR reserves the right to close a beach in the event of a documented health risk including (but not limited to) events such as a wastewater discharge, spills of hazardous chemicals or localized outbreaks of an infectious disease.
In addition to state park beaches, several county- and city-run beaches and other locally managed recreational areas have volunteered to participate in the beach monitoring program this year. Monitoring at these beaches is also scheduled to begin May 23 and will continue into the first week of September.