"We currently have no reason to believe that toxic algae outbreaks this year will be any higher or lower than in previous years," said UNL water resources specialist Tadd Barrow.
"Weather patterns, drought conditions and other factors contributing to the blooms aren't dramatically different this year than they were last year," Barrow said.
Rapid algal growth is called an algae bloom. Blooms can appear and linger anywhere from days to weeks and can persist until the first hard frost in the fall, said UNL lake ecologist Kyle Hoagland, who directs the UNL Water Center.
Numerous environmental factors can trigger a bloom. Lakes with higher concentrations of nutrients, or fertilizers, especially phosphorus, generally are more susceptible to blue green algae blooms, he added.
Some types of blue green algae produce chemical toxins that harm people and animals. "These colorless and odorless toxins may linger in the water for as long as two weeks after the bloom has disappeared," Barrow said.
Fremont State Lake No. 20, which has chronically suffered from toxic algae blooms in recent years, is being monitored weekly for algae toxins by the Nebraska Department of Environmental Qualityand already has tested very high in toxins, Barrow said. A health alert was issued for the lake May 12. Potentially harmful levels of toxic algae also have been registered at Carter Lake, near Omaha.
Algae blooms can pose serious health threats to humans and animals.
Skin irritations and gastrointestinal problems are the main risks to people from algal toxins. In very rare cases, extremely high toxin levels can be fatal.
In recent years, blooms have resulted in only a few reported cases of human illness and skin irritation, but livestock and pets have died after drinking lake water during an algae bloom, Barrow said.
The normal season for algae blooms is May through September, but some lakes still can have high toxin levels as late as December, he said.
UNL Extension's lake management program is continuing a volunteer monitoring program to check lakes for blue green algae. Free test kits are available from Barrow's office so lake owners, users and managers can check their lake for potential toxin producing algae.
In 2005, the program sent 227 free kits across Nebraska. After testing at UNL, "Forty five percent of them contained potentially toxin producing algae and 58, or about 20 percent overall, tested positive for moderate to high concentrations of blue green algae and went to the NDEQ's lab for toxin analysis," Barrow said.
Of the 58 that tested positive for blue green algae, 11 had levels above 20 parts per billion (ppb) of microcystin, a toxic bacteria contained in blue green algae.
"All public lakes with a toxin concentration of more than 20 ppb microcystin are put on the state's health alert status and remain closed to activities such as swimming and other full body water contact until subsequent toxin samples drop below 20 ppb for two consecutive weeks," Barrow said. "During these health alerts, boating and fishing are still allowed with caution."
The free UNL test kits contain instructions on sample collection, a sheet for recording measurements, a questionnaire about the lake, and sample bottles for water and algae. Samples are returned to Barrow for processing and those who submit samples are notified of results.
For more information or a test kit call Hilary Hansen at (402) 472 8190.
Knowing what an algae bloom looks like and avoiding water contact during blooms is important, the two School of Natural Resources experts said.
People should avoid swimming, water skiing, riding personal watercraft or similar activities involving physical contact or swallowing water from lakes with blue green algae blooms, Barrow said.
During a bloom, lake water becomes cloudy with a green or blue green cast and blue green streaks may be visible on the water's surface, Hoagland said.
"At this stage, the lake looks like pea soup or as if someone dumped a light colored green paint in the water. It often develops a strong musty or fishy odor as the algae accumulates and begins to decompose," he said.
Winds can increase the danger of a toxic bloom by blowing algae to the leeward side of a lake where it concentrates in coves or along shorelines.
Blue green algae, which are cyanobacteria, are microscopic organisms commonly found in lakes and ponds worldwide. Special characteristics of blue green algae often allow them to multiply faster than other types of algae, Hoagland said.
Steve Ress
Communications coordinator, UNL Water Center
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