By Hannah Nazarenus

As Nebraska enters the warmer months of the summer, officials with the Department of Water, Energy and Environment say high temperatures may create ideal conditions for harmful algal blooms.

The Departments Surface Water Team samples 57 beaches at 52 public lakes across the state every Monday from May 18 through September 14. They test for microcystin, a toxin produced by certain strains of blue-green algae, and E. coli.

“Typically, we see more algal blooms arise once the water temperature increases, just like any terrestrial plant. Algae grows when it has adequate nutrients and warm temperatures,” David Schumacher, surface water monitoring section supervisor, said.

State officials said blooms and elevated microcystin levels typically appear in July, August and September; they can appear in May or June.

The start of the testing season began slowly with zero health alerts issued in May. In June, health alerts went out for Maskenthine Reservoir in Stanton County, Iron Horse Trail Lake in Pawnee County and two weeks in a row for Rockford Lake near Beatrice.

The monitoring program started in 2004, when a couple of dog deaths at private lakes outside Omaha drew attention.

“That got quite a bit of press coverage to where people were concerned, you know, obviously not only about their pets, but human health when it comes to recreating in bodies of water as it relates to harmful algal blooms,” Schumacher said.

The program began with about 20 lakes that year and has since grown statewide.

Certain lakes are more prone to bloom than others. Sandpit lakes that are enclosed and fed by ground water tend to have less harmful algal blooms. Reservoirs where there is a river or stream that feeds into the lake tend to have more blooms.

While they are naturally occurring, blooms tend to grow stronger in lakes with an abundance of nitrogen and phosphorus, from agricultural or urban runoffs.

“A bloom has kind of the consistency of paint on the surface, or maybe oil,” Justin Haas, State Lakes Coordinator, said. “Usually they’re a dark green, kind of a John Deere green color floating on the surface. As that bloom begins to die, they can turn a blue kind of turquoise color.”

Other signs to look out for include neon green, pea green, blue green or reddish brown water color, a bad odor, scum or film on the surface and green or blue streaks that resemble grass clippings.

Blooms tend to gather near shorelines, where water is shallow and stagnant, the same areas where children and pets often spend the most time.

Once a bloom forms, there is no way to speed up its disappearance.

“You kind of have to let Mother Nature run its course,” Haas said. “We’ve seen a bloom last a couple of days. Sometimes it can last weeks, sometimes even a month.”

Even after a bloom visually looks gone, microcystin can remain in the water for weeks. A bloom in one part of the lake can affect the entire body of water.

“If one of those beaches were to be over eight [parts per billion] in microcystin, we would issue a health alert for the entire lake,” Schumacher said. “These blooms can move around, so just because it starts in one part of the lake doesn't mean it can't get blown to another portion.”

Schumacher said pet owners need to be alert even if they believe the water is safe.

“A lake could be mainly free of a harmful algal bloom, but wind direction could capture all the harmful algal cells and drive it along one shoreline, and you might only see six inches,” Schumacher said. “But if you're walking a dog, he may take a drink from that one spot and get sick.”

Dogs can become sick or die from drinking contaminated water or licking their wet fur and paws. Symptoms can appear within 15 minutes or take several days to develop and may include vomiting, weakness, drooling, difficulty breathing and convulsions.

It's recommended to rinse an exposed pet immediately with clean water while wearing gloves and seeking veterinary care right away if symptoms appear.

In humans, exposure can cause skin rashes, lesions and blisters, and in severe cases, mouth ulcers, nasal ulcers and eye or ear irritation.

Swallowing contaminated water may lead to headaches, nausea, muscle pain, abdominal pain, vomiting, and in extremely rare severe cases, seizures, liver failure, respiratory arrest and death.

Children face higher risks because they tend to swallow more water relative to their body weight. People with liver disease, kidney damage or weakened immune systems are also more vulnerable.

The department also tracks E. coli separately, using the Environmental Protection Agency’s recreational threshold of 235 MPN per 100 milliliters. Lakes that test above that level are flagged on the departments public data page but don’t trigger a health alert.

“The reason why we don’t put out a health alert on those lakes that are high in E. coli is because those levels can change relatively quick,” Haas said. “We do report it so people can make their own informed decisions.”

Officials recommend avoiding water with visible algae, keeping pets and children away from shoreline scum, rinsing off immediately after any contact and not letting pets drink directly from a lake.

Weekly sampling results are posted to the department’s website each Thursday. With temperatures rising, officials say the safest approach is simple. If you can’t tell whether a bloom is present, treat the water as if it might be.

https://nebraskapublicmedia.org/en/news/news-articles/rising-temperatures-mean-threat-of-algal-blooms-at-nebraska-lakes/