Monitoring Set to Resume at State Park Beaches
DES MOINES — As in summers past, the DNR will again monitor and report water quality conditions at state park beaches to safeguard Iowans’ health and enhance understanding of water quality.
The DNR routinely collects and analyzes water samples at Iowa’s 38 state park beaches. The samples are compared to water quality standards to determine the risk of waterborne illnesses for swimmers. All beaches will be monitored at least once per week.
Monitoring at all state park beaches will begin Monday, May 21 and continue through August.
Iowans and visitors can find weekly results on the DNR website at www.iowadnr.gov. For current beach advisories, go to the “Recreation” tab, then select “Beach Monitoring.” On the beach monitoring home page, select “State Park Beaches” under the “Beach Monitoring Results” heading. Clicking on the icon over each beach will open a window containing detailed water quality information. Beachgoers can also get up-to-date advisory information by calling the Iowa Beach Hotline at 319-353-2613.
State park beaches will post a “swimming is not recommended” sign if:
• The geometric mean (a type of average based on the five most recent samples within a 30-day period) exceeds 126 E. coli bacteria per 100 ml of water)
• The beach has had bacteria problems in the past (causing it to be classified as a “vulnerable” or “transitional” beach) and the most recent sample exceeds Iowa’s one-time maximum standard (235 E. coli bacteria per 100 ml of water)
The DNR considers beaches “vulnerable” after three or more years of high geometric means within a five year period. Beaches are no longer “vulnerable” when they have experienced several seasons of good water quality and this condition no longer applies.
“Transitional” beaches include beaches where bacteria problems appear to have been resolved or no longer have a serious impact on water quality. 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 (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, hazardous chemical spills 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. Monitoring at these beaches will also begin May 21 and continue through the week leading up to Labor Day. Water quality information for these areas can also be found on the beach monitoring website.