Frequently Asked Questions about Beach Monitoring
Why monitor beaches?
Swimming in lakes or any other natural body of water involves risks. By far, the greatest risk is drowning caused in part by cloudy water,
fast currents, submerged objects, or the lack of lifeguards.
Water at Iowa’s state-owned swimming beaches is monitored to assess
the public health risk from waterborne diseases that may result from immersion in the water.
What is the DNR monitoring?
Water samples from the beaches are analyzed for microorganisms, known as
bacteria.These indicator bacteria are
one-celled organisms visible only under a microscope.High levels of these bacteria indicate that the water has come into
contact with fecal material.
are commonly used by state environmental agencies and by the U.S. EPA to determine the suitability of beaches for swimming-type uses.
Can these bacteria make me sick?
The indicator bacteria for which we monitor do not themselves make you
sick. These bacteria are easy to
collect and analyze and are relatively safe to handle. They are very common
in the environment, including lakes and rivers.High levels of these bacteria indicate that the water has come into
contact with fecal material and that pathogens or disease-causing
microorganisms may be present.
Why doesn't the DNR monitor pathogens?
Disease-causing organisms, known as pathogens, exist as bacteria,
viruses or parasites.Monitoring
for these pathogens is expensive and difficult.
Large volumes of water are needed to monitor for pathogens because
they are present in such small numbers.
Many different types of pathogens exist and testing for a single pathogen
may not accurately assess the health risk present due to other pathogens.
Because indicator bacteria occur in greater numbers than pathogens
and are easier to isolate in a laboratory, monitoring for them is more
What are the sources of these bacteria and pathogens?
Fecal bacteria, and sometimes pathogens, are present in the intestines of
warm-blooded animals, including humans.
They are carried into the water with fecal material.
Fecal contamination occurs due to improperly constructed and operated
septic systems and sewage treatment plants, manure spills, storm water
runoff from lands with wildlife and pet droppings, or direct contamination
from waterfowl, livestock, or small children in the water.
- How are the samples collected at the beach
Samples are collected weekly at 37 state owned beaches from April
15 through October 31.This period
corresponds to the recreational season when the Iowa Water Quality Standards,
designed to protect swimming-type uses, is
in effect. Water samples are taken at
three locations along the beach and at three water depths (ankle-, knee- and
waist-deep).The water from these
locations is mixed to form one sample, which is placed in a sterilized
bottle and taken to a laboratory for analysis.
What levels of indicator bacteria are considered safe?
The United States Environmental Protection Agency (EPA) has guidelines for
the amount of bacteria acceptable in water bodies designated for primary
body contact recreation, including swimming and water skiing.
In Iowa, these waters are called "Class A waters".
The bacteria level in the water is acceptable if the “geometric mean”
is not greater than 126 colonies per 100 milliliters of water for E. coli
bacteria.According to U.S. EPA
guidelines, the “geometric mean” is calculated using at least five
consecutive samples collected during a 30-day period.
Additionally, Iowa also has a "one-time" standart for E. coli
bacteria of 235 colony forming units per 100 milliliters of water.
What factors cause high levels of bacteria?
Fecal contamination of
beach water occurs due to improperly constructed and operated septic systems and
sewage treatment plants, manure spills, storm water runoff from lands with
wildlife and pet droppings, or direct contamination from waterfowl, livestock,
or small children in the water. In Iowa,
rain appears to be one of the most important factors in generating high levels
of bacteria.Surface runoff after a heavy
rainfall may transport high levels of fecal bacteria to the water at the beach.
The rain also increases the sediment in the water causing it to be murky.
Since bacteria are destroyed by sunlight, murky water aids in their
What are the potential illnesses associated with swimming?
Thousands of people swim at Iowa’s beaches
every year and most of them do not get sick.
However, children, the elderly and people with weakened immune
systems have an increased risk of becoming ill when in contact with
contaminated water.A variety of diarrheal diseases, and other infections such
as skin, ear and respiratory infections, are associated with swimming in
contaminated water. Diarrhea is one of the most common illnesses associated
Diarrhea is spread when disease-causing microorganisms from human or
animal feces get into the water.
You can get diarrhea by accidentally swallowing small amounts of water that
contains these microorganisms.
To date, the DNR has received no verified reports of illnesses caused by
swimming or water skiing in Iowa’s waters.
However, these illnesses could be under-reported because the symptoms
are so common and people can be infected by these pathogenic microbes
through other means, such as from contaminated meat, not washing their hands
after using the bathroom or changing diapers.
How can I avoid getting sick?
Avoid swimming after a heavy rainfall when indicator bacteria levels are
generally higher and the water is murky. Avoid swallowing the water.
Young children swimming at the beach can leak fecal bacteria and
associated pathogens from their diapers, so change your child’s diapers often
and visit bathrooms frequently.
If you or your child has diarrhea, please stay out of the water
because you may contaminate the water with fecal material.
Although swimmers with diarrhea do not mean to contaminate the water,
this is often how disease is spread.
Can I eat fish from waters with high levels of fecal contamination?
Yes, high levels of indicator bacteria or
pathogens have no influence on the quality of fish for human consumption.
While alive, the fish is protected from water-borne contaminants by
the skin, scales and mucus covering its body.
Proper fish cleaning, rinsing, refrigeration and cooking should
always be used.