Swimming is “not recommended” in 11 locations.

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Swimming is not recommended at 11 state park beaches in Iowa due to high levels of bacteria, according to the state’s Department of Natural Resources. A 12. was closed as a precaution last week after a swimmer was infected by a “brain-eating amoeba”.

officials at The Iowa Department of Natural Resources collects samples from the state’s swimming beaches on a weekly basis every summer to determine whether the public is at risk of contracting waterborne diseases from going in the water.

The state agency works with various public health and administrative agencies across the state to update the public on the most up-to-date water quality conditions.

The latest conditions, updated Friday, include 11 beaches across the state in the agency’s no-swimming category. One of them, Big Creek Beachis located near Saylorville Lake, about 20 miles from Des Moines.

Here’s how officials determine if the water is safe for swimming and the latest beach surveillance data from DNR.

More:Missouri resident infected by rare ‘brain-eating amoeba’ Naegleria fowleri dies; Southern Iowa Beach remains closed

State Water Quality Technician Elizabeth Heckman heads to the beach June 2 for weekly water samples at Lake Macbride in Solon.  The Iowa Department of Natural Resources reported 118 swimming notices at the state park's 39 beaches after conducting weekly tests like this from Memorial Day weekend through Labor Day.

How does the monitoring work?

DNR officials collect water samples from 40 state beaches weekly from the week before Memorial Day through Labor Day.

Water samples are taken at three locations along the beach and at three water depths – ankle, knee and waist depth. “The water from these locations is mixed to form a sample that is placed in a new bottle and taken to a laboratory for analysis,” the DNR’s website says.

What causes contamination?

According to DNR officials, fecal contamination of beach waters can come from improperly built and operated sewage treatment plants and treatment plants, manure contamination, stormwater runoff from areas with wildlife and pet feces, or from direct contamination from waterfowl, livestock, or small children in the water.

Rain is one of the biggest factors in creating high concentrations of bacteria in Iowa, according to the DNR. Runoff from a heavy shower can lead to high concentrations of fecal bacteria and contaminate water on beaches. Rain also increases sediment in the water, making it cloudy, which helps bacteria survive.

Who is at risk?

Thousands of people swim on Iowa’s 40 beaches each year, and most don’t get sick. But DNR officials say children, the elderly and those with compromised immune systems are at increased risk of getting sick from contaminated water.

Diarrhea is one of the most common diseases that can occur when swimming in contaminated water. Other infections include skin, ear, and respiratory infections.

What water levels are safe?

Officials at the Department of Natural Resources follow U.S. Environmental Protection Agency guidelines to determine whether bodies of water used for recreation — like swimming and water skiing — are safe based on the amount of bacteria.

Bacterial levels in the water are “acceptable” when the geometric mean is no greater than 126 colony-forming units per 100 milliliters of water for E. coli bacteria, according to EPA guidelines.

The geometric mean is calculated using at least five consecutive samples collected over a 30 day period. Iowa also has a “unique” standard for E. coli bacteria of 235 colony-forming units per 100 milliliters of water.

What classifications are there?

DNR lists data on whether swimming conditions are acceptable at 40 of its state park beaches and many locally managed beaches. Beaches are classified on a color-coded map at IowaDNR.gov.

The current conditions are listed as follows:

  • For swimming ok: (denoted by a green dot)
  • Swimming not recommended: (Indicated by a yellow dot). DNR officials will release this notice if the beach exceeds the Iowa water quality standard geometric mean for E. coli; is a “Vulnerable” or “Transitional” beach that exceeds a unique maximum water quality standard for bacteria; and/or exceeded the EPA limit for blue-green algae toxins.
  • Beach closed: (denoted by a red dot)
  • local beach: (Indicated by a blue dot) The DNR also provides periodic data for locally monitored beaches.
  • Insufficient data: (Indicated by a white dot).

DNR officials annually classify the state park’s beaches into one of three categories based on their history of bacterial results over the past several years:

  • Vulnerable: Beaches are considered at risk if the geometric mean is exceeded for three or more of the five most recent sampling seasons.
  • Crossing: The beach geometric mean has been exceeded in two or fewer sampling periods in the last five years and has been classified as “Vulnerable” in past observation periods.
  • Less vulnerable: The beach geometric mean has been exceeded in two or fewer sampling seasons out of the five most recent and has been listed as “transitional” or “less vulnerable” in past monitoring seasons.

Swimming is “not recommended” at these Iowa beaches.

Emerson Bay Beach at Emerson Bay State Recreation Area

  • 2022 Beach Classification: Vulnerable
  • Last tested on July 13th

Black Hawk Beach in Black Hawk State Park

  • Beach Classification 2022: Less Vulnerable
  • Last sampling: July 12th

Green Valley Beach in Green Valley State Park

  • Beach Classification 2022: Less Vulnerable
  • Last tested on July 13th

Geode Lake Beach in Geode State Park

  • Beach Classification 2022: Less Vulnerable
  • Last tested: July 13th

Backbone Beach at Backbone Beach State Park

  • 2022 Beach Classification: Vulnerable
  • Last tested on July 13th

George Wyth Beach in George Wyth Memorial State Park

  • 2022 Beach Classification: Vulnerable
  • Last sampling: July 13th

Pine Lake South Beach in Pine Lake State Park

  • 2022 Beach Classification: Vulnerable
  • Last sampling: July 12th

Beeds Lake Beach in Beeds Lake State Park

  • 2022 Beach Classification: Vulnerable
  • Last tested on July 13th

Big Creek Beach in Big Creek State Park

  • Beach Classification 2022: Less Vulnerable
  • Last sampling: July 12th

Lake Darling Beach in Lake Darling State Park

  • 2022 Beach Classification: Vulnerable
  • Last sampling: July 13th

Prairie Rose Beach in Prairie Rose State Park

  • 2022 Beach Classification: Vulnerable
  • Last sampling: July 13th

Iowa state beaches are closed to swimming

Lake of Three Fires Beach in Lake of Three Fires State Park

  • Beach Classification 2022: Less Vulnerable
  • Last sampling: July 13th

The beach closed on July 7th after a A Missouri man has been diagnosed with a rare brain-eating amoeba. Officials said the man who died from the infection was swimming at the beach in late June. The beach will remain closed until the US Centers for Disease Control and Prevention complete an investigation and determine if the lake was the source of the infection.

Beach surveillance hotline

That DNR beach surveillance website and Hotline are updated on Fridays during the surveillance season.

Those looking for updated beach advisories can call the hotline at 515-725-3434 or email [email protected]

Virginia Barreda is a trends and general assignments reporter for the Des Moines Register. She can be reached at [email protected]. Follow her on Twitter at @vbarreda2.

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