Beaches: How Safe is It? - EH: Minnesota Department of Health

Beaches and Recreational Waters in Minnesota
How Safe is It?

Photo of swimmers at Voyageurs The most common illnesses contracted by swimmers are infections of the skin, eyes, ears, nose, and throat. These infections can be caused by bacteria, such as Pseudomonas aeruginosa and Staphylococcus aureus, which are most frequently transferred from one bather to another in crowded swimming areas.

Can beaches make you sick?

Recreational waters generally contain a mixture of pathogenic (disease-causing) and non-pathogenic microorganisms. These microorganisms may naturally inhabit the water or come from sewage effluents, wildlife, farming activities, domestic animals, industrial processes or people.

Why is my beach closed?

Beaches are closed to protect the public health, usually as a result of increased bacteria levels in water. Closure may be for a variety of reasons, for example, pollution events (such as breaks in sewage pipes or rainfall carrying pollutants to water) or transmission of pathogens by infected bathers.

What are waterborne pathogens?

Waterborne pathogens are disease-causing germs that live in water. Waterborne pathogens can be classified as bacteria, viruses, protozoa, algae, or multi-celled parasites.


Bacteria are virtually everywhere. They are in the air, soil, water, and in and on plants, animals and people including us. Disease-causing species are a comparatively tiny fraction of the total bacteria. Certain bacteria are beneficial by producing antibiotics; others live symbiotically in the guts of animals (including humans), or on the roots of certain plants, converting nitrogen into a usable form. Bacteria put the tang in yogurt and the sour in sourdough bread; bacteria help to break down dead organic matter; bacteria make up the base of the food web in many environments.

Fecal coliform and E. coli are two different indicators of the presence of bacteria from fecal sources. “Fecal coliforms” is the name of a large group of bacteria found in feces whereas the indicator E. coli is strongly correlated with the presence of pathogens.

E. Coli is the abbreviation for the bacterium Escherichia coli which make up approximately 0.1% of the total bacteria within an adult’s intestines. The majority of E. coli-associated illnesses are acquired by eating contaminated food, but some illnesses have resulted from consuming contaminated drinking water or swallowing swimming water.

Waterborne bacteria also include shigella, salmonella and campylobacter.


Noroviruses are members of a group of viruses called caliciviruses, also known previously as “Norwalk-like viruses.” Norovirus is also called viral gastroenteritis, food poisoning, and calicivirus.


Giardia and cryptosporidium are protozoan (single-celled) parasites that cause gastrointestinal illnesses. Drinking untreated water and accidentally ingesting untreated water while swimming are common causes of gastrointestinal illness. Hikers, paddlers, and other outdoor users should always boil, filter, or treat water from unknown sources to reduce the likelihood of contracting these infections.

Multi-celled Parasites

“Swimmer’s Itch” is caused by a Multi-celled parasite called a trematode. The itch occurs when the parasite leaves its snail intermediate host and penetrates the skin of the wrong final host – a person – instead of the right one (usually a bird).

Blue-green algae

Algae is typically found in backwater or protected areas of natural waters, especially after a period of warm weather. Runoff into lakes often contains excess nutrients such as nitrates and phosphates. Algae feed on these nutrients and grow at high rates known as “blooms”. As they grow, algae produce toxic materials that may cause gastrointestinal illness.

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What are the health risks?

Hazards from recreational bathing are related to exposure through swimming or ingestion. The most common form of illness contracted from swimming in water is gastroenteritis - symptoms of gastroenteritis include nausea, vomiting, diarrhea, stomach pain, headache and fever. Other illnesses such as respiratory illness or infections may also occur after exposure to contaminated waters.

How do I know if the water is safe?

Public Health officials access water quality through a combination of sanitary inspection and microbial water quality assessment.

There is no simple way of determining if waters are free of contamination without laboratory tests. Local authorities may also decide to take precautionary measures such as testing more frequently, chasing away birds, grooming the beach to remove contaminants and possibly closing the beach.

How is water tested?

Water from public beaches is sampled for elevated levels of fecal coliform and/or E. coli. When high levels are found, beaches are closed to reduce likelihood of disease. Unfortunately, water testing is often difficult for private beach owners and for popular swimming areas that are not monitored by health departments.

The E. coli variant known as 0157:H7, made famous in several meat contamination cases, has also been associated with drinking contaminated water and can cause severe intestinal illness. In very rare cases, it can cause severe kidney problems (such as hemolytic uremic syndrome).

Although coliform bacteria themselves are not usually harmful, these bacteria can be associated with other disease causing bacteria or parasites. In order to maintain healthy swimming beaches, the State of Minnesota established the following recommendations:

  • The average of five swimming beach samples in a 30-day period should not exceed a count of more than 200 fecal coliform bacteria cells per 100 mL of water.
  • No one sample should have a fecal coliform count greater than 1,000 bacteria colonies per 100 mL of water. If a sample exceeds 1,000 bacteria colonies per
    100 mL, consideration should be given to closing the swimming beach.

Who is responsible for testing beaches?

The U.S. Environmental Protection Agency has recommended criteria for beach water monitoring. Congress has recently enacted the BEACH Act that requires states to adopt EPA’s recommended standard and encourage states to monitor and notify public when health standards are exceeded.

Many local public health departments monitor beach water quality. MDH maintains a listing of Contact information for County/City Local Health Departments in Minnesota.

The Minnesota Department of Health administers the Minnesota Lake Superior Beach Monitoring Program. This federally sponsored program monitors bacterial counts at swimming beaches along the Minnesota North Shore of Lake Superior. Warnings to swimmers are posted when the counts are above acceptable levels.

When will the beach be re-opened?

When public health officials, in conjunction with state and local authorities, determine that the waters are safe for swimming. Testing and analysis typically take at least 48 hours.

How does this stuff get here?

Factors that contribute to elevated bacteria levels include high water temperature, animal droppings, rainfall, low water levels and bathing practices.

Stormwater Pollution:

Beaches and other recreational waters can become polluted by stormwater when rain and other sources of runoff transport pollutants (animal wastes, paints, automotive fluids, cleaners, fertilizers, etc.) into storm drains or gutters.

Sewage Spills:

Recreational waters can also become contaminated with infectious materials (body fluids, human or animal feces, etc.) when sewer lines break or overflow. Sewage spills typically occur when lines break due to age or become blocked. Excessive rain can also cause a substantial increase in flow to a wastewater treatment facility resulting in an overflow or bypass of untreated or partially treated wastewater to the environment.

Natural Sources:

Bacteria from soils, decaying vegetation, wildlife, and birds can also contaminate recreational waters. These sources can elevate bacteria levels in recreational waters, especially those with poor water circulation.

Can I eat fish from here?

Most fish are healthy to eat. And fish are an excellent source of low-fat protein. Eating fish may also reduce the risk of heart disease, diabetes and other chronic illnesses. But any fish (store-bought or sport-caught) could contain contaminants such as mercury and PCBs that can harm human health - especially the development of children and fetuses. You can't see, smell, or taste the mercury or PCBs in fish. That's why it is important to know which fish are safer than others to eat. MDH provides detailed fish consumption advice.

How can beach closures be prevented?

Healthy swimming behaviors are needed to protect you and your kids from Recreational Water Illnesses and will help stop germs from getting in the water in the first place.

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Updated Wednesday, September 25, 2013 at 08:10AM