Precautions and Facts Regarding Harmful Algal Blooms
(Toxic Algae) at Nebraska Lakes and Beaches

Updated June 22, 2023

A Joint Publication from the
Nebraska Department of Health and Human Services – Division of Public Health and the
Nebraska Department of Environment and Energy

What is a Harmful Algal Bloom Health Alert?

The Health Alert designation for Harmful Algal Blooms (also referred to as “toxic blue-green algae”) means that the state has determined that the level of toxins in the water make it potentially unsafe for full-body recreational activities, such as swimming. The toxin being measured is microcystin, which is generated from certain strains of blue-green algae.

During a Health Alert at a public lake, signs will be posted advising the public to use caution. Affected swimming beaches will be closed. Boating and other recreational activities will be allowed, but the public will be advised to use caution and avoid prolonged exposure to the water, particularly avoiding any activity that could lead to swallowing the water.

Starting in the 2020 recreational season, the level to trigger a Health Alert declaration is 8 parts per billion of the toxin microcystin. This is a lower threshold than previous years, based on recommendations issued in 2019 by the U.S. Environmental Protection Agency (EPA). Previously, the State of Nebraska had set a limit of 20 ppb, but adopted the new limits after concluding that the new EPA threshold is based on the best scientific evidence available, and is protective of public health.

What is a Harmful Algal Bloom?

Harmful Algal Blooms (HAB), also known as toxic blue-green algae, refer to certain strains of cyanobacteria that produce toxins. HABs often are a distinct blue-green color but may also appear to be green, brown or red. The toxins associated with HABs have been found in a number of Nebraska lakes sampled.

HABs can dominate the algal populations of a lake under the right combinations of water temperature, low water depths, and nutrients (such as high nitrogen and phosphorus concentrations from wastewater discharges and runoff from agricultural land and communities).

What should I look for to avoid Harmful Algal Blooms?

HABs usually have heavy surface growths of pea-green colored clumps, scum or streaks, with a disagreeable odor. It can have a thickness similar to motor oil and often looks like thick paint in the water. Algae blooms usually accumulate near the shoreline where pets and toddlers have easy access and the water is shallow and more stagnant. It is important to keep a watchful eye on children and pets so that they do not enter the water. Aspects to watch out for include:
  • Water that has a neon green, pea green, blue-green or reddish-brown color.
  • Water that has a bad odor.
  • Foam, scum or a thick paint-like appearance on the water surface.
  • Green or blue-green streaks on the surface.
  • Areas with algae that look like grass clippings floating in the water.
  • When algal blooms are present at a lake, avoid protected bays and shorelines on the windward side of the lake. These are areas that generally have higher concentrations of algae, and potentially toxins.

What are the risks and symptoms?

Pets and farm animals have died from drinking water containing an HAB (or licking their wet hair/fur/paws after they have been in the water). Toxins produced by HABs have been known to persist in water for up to 14 days after the bloom has disappeared.

The risks to humans come from external exposure (prolonged contact with skin) and from swallowing the water. Symptoms from external exposure are skin rashes, lesions and blisters. More severe cases can include mouth ulcers, ulcers inside the nose, eye and/or ear irritation and blistering of the lips. Symptoms from ingestion can include headaches, nausea, muscular pains, central abdominal pain, diarrhea and vomiting. Severe cases could include seizures, liver failure, respiratory arrest – even death, although this is rare. The severity of the illness is related to the amount of water ingested, and the concentrations of the toxins.

Are some people more at risk?

Yes. Some people are at a greater risk from HABs than the general population. Those at greater risk include:
  • Children enjoy playing along the shoreline of lakes, but may have less awareness about potentially hazardous conditions, causing for greater opportunity for exposure. Based on body weight, children tend to swallow a higher percentage of water than adults, and therefore could be at greater risk.
  • Individuals with liver disease or kidney damage and those with weakened immune systems.

Here are some tips on what you can do, and things to avoid:
  • Be aware of areas with thick clumps of algae and keep animals and children away from the water.
  • Don’t wade or swim in water containing visible algae. Avoid direct contact with algae.
  • Make sure children are supervised at all times when they are near water. Drowning, not exposure to algae, remains the greatest hazard of water recreation.
  • If you do come in contact with the algae, rinse off with fresh water as soon as possible.
  • Don’t boat or water ski through algal blooms.
  • Don’t drink the water, and avoid any situation that could lead to swallowing the water.

Is it safe to eat fish from lakes that are under a Health Alert?

Although research is limited, most information to date indicates that toxins do not accumulate significantly in fish tissue, which is the meat that most people eat. At this time, fishing is permitted at lakes that are under a Health Alert. This issue is continuing to be studied, and this fact sheet will be updated if more conclusive information becomes available.

Where can I find out more information about lake sampling for Harmful Algal Blooms?

The Nebraska Department of Environment and Energy (NDEE) conducts weekly sampling at 50 public recreational lakes across the state from May 1 to September 30. Sampling information is updated weekly on the agency web site, http://dee.ne.gov

If I think a public lake has a Harmful Algal bloom, who do I contact?

Please contact NDEE’s Surface Water Unit at (402) 471-0096, or (402) 471-2186, or e-mail NDEE.BeachWatch@Nebraska.gov

If I am experiencing health symptoms, who do I call?

If you experience health symptoms or illness related to Harmful Algal Blooms, notify your physician, and call the Nebraska Regional Poison Center at 800-222-1222 for immediate health questions. If you have general questions about human and animal exposures to HABs and related illnesses, contact the Nebraska Department of Health and Human Services at (402) 471-2937 or dhhs.epi@nebraska.gov.