That paint-like scum that covers some Iowa lakes every summer isn’t just gross and smelly. People, pets, and livestock coming into contact with or ingesting toxins produced by the algae are at risk to symptoms including skin rashes, gastrointestinal issues and, in high doses, liver failure.
The toxin, called microcystin, is a liver toxin produced by some strains of cyanobacteria, commonly called blue-green algae. It has been tracked in Iowa state lakes since 2005 in order to warn the more than 1 millionbeach-goers and boaters making 12 million visits to the lakes each year when concentrations rise above levels of 20 micrograms per liter.
Although the number of reports of human and animal illness from the toxin has remained fairly steady, some scientists say the annual algal blooms may be growing more severe.
“I think we can be fairly confident in saying that the number of blooms, or the severity of the blooms, appears to be increasing,” Mary Skopec, who heads the Iowa Department of Natural Resources beach monitoring program, said.
In fact, two microcystin advisories posted this week brought the total number of warnings this year to 25, surpassing a record of 24 set in 2013, according an Iowa Environmental Council news release sent Friday.
This increase seems to mirror national trends, she said. Longer periods of warm temperatures as well as the high levels of nutrients, like nitrogen and phosphorus, in Iowa lakes could be contributing to this increase in severity but the exact cause isn’t known, she said.
“I think we really just aren’t at a point where we know definitely why we are seeing that increase in blooms.”
State toxicologist Stuart Schmitz said the Iowa Department of Public Health and the Iowa Department of Natural Resources have participated in a surveillance program of harmful algal bloom illness since 2008. He said five to 14 cases of suspected human exposure to microcystin are reported.
The highest number of reported human cases, 14, occurred in 2011, Schmitz said. The peak coincided with a triathlon in Big Creek State Park, in central Iowa near Polk City, on Sept. 11, during which more than 250 people may have been exposed to a bloom that started growing around the time of the race. Beach monitoring ended the week before the race, but had shown toxin levels to be safe.
“After we heard of that contact, our coordinators got that information out to the participants to see if they had any concerns or symptoms,” he said.
Schmitz said people are at risk for two categories of symptoms: skin irritation, which is the most common and includes rashes, blisters and itching; and gastrointestinal symptoms, including nausea, vomiting and diarrhea.
Symptoms can last from a few days to a week and can depend on whether or not the person only had skin contact with the toxin or ingested some of the water.
A report on cases from 2012 that IowaWatch reviewed shows a 21-year-old female who experienced a sore throat lasting for about a week as well as “fatigue, fever, headache, loss of appetite, nasal congestion, nausea, joint pain and dizziness that lasted for several days” after being exposed to the toxins for about a half-hour.
A 5-year-old boy exposed that same year to lake water with high microcystin levels for roughly eight hours had a rash that lasted about three weeks, the report shows.
Suspected animal illnesses reported in 2010 included two dogs, one with “weakness, inability to walk, diarrhea, vomiting, and low body temperature,” and another with “lethargy, fever, rapid breathing, and tremors.” In both cases, symptoms subsided after 24 hours. But in the third animal illness report that year, a cow was “observed dead a short time after exposure to a lake that had experienced an algal bloom.”
The effects of long-term exposure to low doses of the toxin are largely unknown, Schmitz said.
He said people should shower after using lakes that have an active bloom and “if they don’t have to go in there, stay out.”
He said cases of exposure likely aren’t reported to the state, but that it is hard to estimate how many cases there might be. “I think I could confidently say that the number of cases that come in to the department are probably underreported, but to what degree, I’m not sure,” he said.
Microcystin is relatively new on the scene of environmental concerns. The Iowa Department of Natural Resources beach monitoring program has tested for E. coli since 2000.
Skopec said the state started testing for microcystin in 2005 following reports of dead geese on Carter Lake near Council Bluffs and a big algal bloom in Big Creek Lake.
“We’ve known for a long time that livestock when they consume blue-green algae from a farm pond would die, but I don’t think anybody really saw that as a human health risk,” Skopec said.
Initially testing was only done where there were reports of algae blooms, but she said in 2008 and 2009 the program started doing regular microcystin testing. The testing runs from Memorial Day to Labor Day at roughly 40 state-owned beaches.
Since then, she said Iowa has had increasing numbers of microcystin advisories. The advisories are issued when the amount of the toxin in the water tops 20 micrograms per liter, a level listed by the World Health Organization as carrying a high relative probability of acute health effects during recreational exposure. Levels above 10 micrograms per liter are considered a moderate risk, but do not result in a health advisory at Iowa beaches.
A day at the beach: testing water quality
In order to track toxin levels at state parks, the department sends people to lakes to gather water at the swimming beaches.
Connor Nicholas, 22, was doing just that on July 30 as he loaded coolers and equipment into a white state-owned van.
The Iowa State University senior worked with the beach monitoring program over the summer, driving across western and central Iowa to gather water samples.
On this day, Nicholas was gathering follow-up samples from three state parks: Brushy Creek in Webster County, Twin Lakes in Calhoun County and Prairie Rose in Shelby County. Each had tested high for either E. coli bacteria or microcystin in samplings gathered earlier in the week.
Nicholas, an environmental science major, said he wasn’t familiar with microcystin before he started working for the program.
“At first you are unsure what to look for, but later on, as things start to go off the charts, you catch on and learn what to look for. “
He said the blooms can look different, varying from a green powder-like substance to something that “looks like fish eggs.”
Large blooms, like the one he saw at Green Valley State Park in Union County, have a certain smell.
“It’s hard to explain. It’s kind of like a sharp, putrid smell. Not like eggs or sulfur-based. But once you’ve smelled it, you don’t forget it,” he said.
Before wading into the water at the first beach, Brushy Creek, he donned a pair of green waders and a life jacket, attached a large plastic jug to the front with a carabiner.
Vials of water are gathered from nine points, wading into ankle-deep, knee-deep and chest-deep water to collect samples on the left, center and right sides of the swimming area.
These samples are then combined in the large jug to form a representative sample of the area.
On this morning, the beach is closed for construction and empty of swimmers. But Nicholas said he sometimes sees people swimming despite advisories.
“A lot of the issue is just people not paying a lot of attention. I’ve been to a lot of lakes where people are swimming and there’s been a bloom, E. coli or algae. I’ll usually approach them and tell them it’d be a good idea if their little ones wash up afterwards because we’ve been monitoring the lake and the toxin or the E. coli levels are high,” he said.
State parks are required to post signs warning of high levels of microcystin. Topped with “WARNING” written in all capital letters, the yellow signs note, “Concentrations of toxins produced by blue-green algae currently exceed acceptable guidelines for recreational use.”
The sign discourages swimming, warning beach-goers to keep kids and pets away from the water and to avoid areas of concentrated algae when boating. It also advises contacting a doctor of veterinarian if a person or pet experiences a sudden or unexplained illness.
But Nicholas said despite the signs and occasional news coverage, many people don’t seem to know much about the toxin.
The Kothe family of Phoenix, Arizona was visiting the park at the west beach of North Twin Lake when Nicholas pulled up and got out to test the water. An algae bloom earlier that month had prompted advisories and signs were posted at the beach warning swimmers of microcystin toxins in the water.
Andy Kothe, who was watching his two kids Samantha, 3, and Drew, 4, play in the sand at the playground, said he didn’t know much about the advisory for high levels of microcystin. But the family hadn’t spent much time in the water during their week-long vacation visiting family because their boat was broken down.
His wife, Lindsay Kothe, originally of Fort Dodge, said she spent many summers on the lake as a kid and the family still returns to visit.
“My grandparents were originals out here at the lake, so I grew up here. The water has never been a concern,” she said, but added that, “you always have to be careful and give the kids a bath and make sure there’s no lingering problems.”
“I have heard somewhere in the family that this blue-green algae happens every year, that it’s just part of the cycle and it’s just now been brought to people’s attention. But I don’t know if that’s true,” she said.
During his rounds, Nicholas’ outfit, the waders and lifejacket, elicit questions.
Rhonda Gorden, of Lake City was sitting in her car in a North Twin Lake park when Nicholas pulled up and started unloading his gear.
“Is the water okay here yet?” she asked him.
Gorden said she had heard that the water wasn’t safe for people to go in and it could make them sick. Although she said she saw people out on the lake despite the warnings.
She said her family often camps in the area and was planning on a camping trip the following weekend. The water quality wouldn’t affect those plans, she said, but she didn’t think she’d be getting in the water.
“No, no. I don’t, but my kids do,” she said.
Anke Hildreth, of Fort Meyers, Florida, and her husband were running through the park and stopped to talk to Nicholas about the algae bloom. They had come to Iowa for RAGBRAI and then stopped to visit her husband’s family in Rands, also in Calhoun County.
Although Hildreth said the bloom in the lake hadn’t impacted their visit, it had influenced her choice to participate in a local duathlon, the biking and running portion, instead of the full triathlon, which includes swimming.
“I would not venture into the water,” she said.
“If you are doing above the water sports, like water skiing, you don’t necessarily have that close contact. You might fall in but you don’t necessarily swallow it. Swimming tends to be a little bit different. You’re not supposed to swallow the water, but the tendency is there.”
By Aug. 3, toxin levels had dropped under the advisory level, at just under nine micrograms per liter, the department’s beach monitoring website showed. But the site still warned visitors to “avoid areas of algae scum.”
Skopec, who runs the tests on the water samples, said it is hard to predict when or if an algae bloom is going to produce the microcystin toxin.
In order to test for the toxin, the samples go through three freeze-thaw cycles to break apart the cyanobacteria cells that can hold the toxin inside.
In a Department of Natural Resources lab in Des Moines, Skopec sat looking at a group of frozen test tubes – her “popsicles.” The five vials of water samples emitted small popping and cracking noises as they warmed up from the -80 degree Celsius freezer.
One was dark green, another a murky brown, a third was layered blue and green, one was hazy green and one looked like pure, clear water. Both the blue-green and the clear ones tested above the recreational health advisory levels for microcystin.
“Therein lies our problem,” she said.
The samples had been taken during the previous week, July 27 through 31, from Lake Wapello in Davis County, Brushy Creek Lake, Black Hawk Lake in Sac County, Kent Park Lake in Johnson County and Green Valley Lake in Union County, respectively.
The clear sample and the blue-green sample tested above the recreational health advisory levels — 20 micrograms per liter — meaning swimmers should steer clear of Black Hawk and Green Valley lakes during the next week, until the next round of testing comes in.
Kent Park tested at 12.5 micrograms per liter — not high enough to trigger an advisory, but Skopec said the state would monitor the lake to make sure toxin levels didn’t rise further.
Skopec said that she might be able to predict whether or not a lake will have an algae bloom, based on the level of nutrients in the water and whether the days will be hot and sunny, but can’t predict if a bloom will release toxins.
How an advisory is determined
Skopec said she thought the U.S. Environmental Protection Agency might release new, lower guidelines for microcystin in recreational waters after the EPA released new microcystin drinking water advisory levels this year.
So far, it has not.
The EPA published new proposed drinking water advisories for microcystin in May. Previously the advisory level was 1 microgram per liter.
The new guideline is a tiered system that lowered the health advisory level for children younger than school age to 0.3 micrograms per liter, and increased the level to 1.6 micrograms per liter for all other age groups.
New advisory levels for cylindrospermopsin also were issued, at 0.7 micrograms per liter for children and 3.0 for all other age groups.
Health advisories are different from regulations. They provide technical guidance to state and local officials, identifying public health issues and concentrations of contaminants that could lead to adverse health effects, according to the EPA's news release.
Although the science behind the toxins can be complicated, Skopec said simply using common sense when enjoying Iowa’s lakes is key to decreasing one’s risks.
“If all the indications are that things are fine — clear water, hasn’t had a recent bloom — I wouldn’t be scared to go into that water. I don’t want people to panic. I just want people to use common sense and good information to recreate,” she said.
Information is available on the department’s beach monitoring websiteas well as its beach monitoring hotline. However, she said not all beaches are monitored.
“In Iowa, officially we are only testing about 40 beaches,” she said. “So just because it’s not posted with an advisory, people should still exercise caution if they see very green, blue-green scummy water. Because not all water bodies are going to be tested and posted.”
Pets and livestock
That caution extends to pets and other animals, such as livestock.
Steve Ensley, a clinician with the Iowa State College of Veterinary Medicine, said he typically fields about a dozen calls about small animals, such as dogs, and a dozen calls about larger animals, like livestock, each year that are suspected to have come into contact with microcystin.
He hadn’t received any reports from Iowa doing into mid-August this year, which is fairly abnormal, although he had a report of potential dog exposures in Minnesota, Ensley said.
“So far this year — keep our fingers crossed — we haven’t had anything,” he said.
He said exposures don’t necessarily cause death; it depends on the concentration of the toxin. However, he said tiny amounts of microcystin, 1 part per billion concentrations, can cause liver damage.
He said no treatment can be given if an animal comes into contact with microcystin.
“If you didn’t pay any attention to the pond until after the dog came out, the best thing you can do it try to wash them immediately before they have a chance to lick anything off the fur,” he said. “If they ingested water when they were swimming, there’s not much you can do.”
He said connecting contaminated water with the cause of the illness is hard sometimes because symptoms can be delayed by two or three days.
Pet or livestock owners can look for certain signs, he said, including lethargy and a yellow tinge to the white part of the animal’s eyes, which is a sign of liver damage.
During his 15 years as a diagnostic clinician, he said he hasn’t seen an increase in the number of cases dealing with microcystin, but said it was a consistent problem every year.
For some lakes, such as Green Valley Lake near Creston, algal blooms are an annual occurrence. But Green Valley Park Ranger Alan Carr said he’s hopeful restoration efforts in the lake and the watershed will help clear up the water.
“We’ve done a lot of lake preservation work in the past few years,” Carr said. “In part to try to lessen (the blooms) or alleviate them.”
He said the lake hadn’t reached that point yet. On that particular day, July 31, the lake was still green from a bloom that had been around for nearly three weeks. He said the bloom hadn’t impacted the campground, which was still full every weekend. But high toxin levels affected swimmers and some boaters and water skiers.
He said the blooms seemed to start later in the year this summer, which he hoped could be attributed to the restoration work that’s been done.
“I have to believe that the work we’ve done, not only in the lake itself but also in the watershed in cooperation with the landowners, is having some positive effects,” he said.
That work, part of a statewide Lake Restoration Program under the Iowa Department of Natural Resources, included removing problematic fish species like yellow bass and common carp, dredging nearly 250,000 yards of sediment out of the lake, rebuilding a spillway to prevent carp from reentering the lake and building up existing silt dikes that work to keep sediment and nutrients out of the lake.
Landowners in the watershed also participated through efforts to reduce nutrient runoff and sediment loss, such as terracing and maintaining conservation reserves.
The work wasn’t done specifically to address algae problems, Carr said, but rather to improve overall water quality.
Green Valley is one of more than 20 lakes across the state that have undergone restoration work and are now in maintenance, according to the program’s annual report. An additional 20 lakes have projects in progress and 14 more are in the planning and evaluation stages.
The program, which requires an annual appropriation by the Iowa Legislature every year, received roughly $70.6 million from fiscal 2007 through fiscal 2015, averaging about $7.8 million each year, the annual report shows.
“It’s been a very successful program,” said Martin Konrad, of the Department of Natural Resources fisheries bureau. “I don’t see it ending any time soon. It seems like the politicians are making an effort to fund this program year after year.”
He said after restoration efforts are completed, water quality can be improved within the next year.
He pointed to Black Hawk Lake as an example. The department worked to get a large carp population out of the lake and saw a quick impact on the water and aquatic plant life.
Carp eat plants at the bottom of the lakes, stirring up sediment and releasing nutrients into the water. This contributes both to murky water and to the nutrient-high conditions that encourage algae blooms.
“Once we got the carp out of there it started to clear up. When you have good water quality like that your aquatic plants can grow,” he said.
Skopec said the restoration efforts have worked well on some of the shallow lakes with past algae bloom issues.
And prevention efforts are probably the best way to deal with the blooms, she said.
Although algaecides, such as copper sulfate, can be used to kill the algae, it also can kill fish. And once the algae dies and the cells break apart, microcystin can be released into the water, she said. Other products to prevent stagnant conditions in lakes can be expensive.
However, the clearer water and vegetation growth brought on a new challenge.
“Currently the recreational power boaters are starting to complain that we’ve got too many water plants,” Konrad said, leading the department to wrestle with the question of how to balance between recreational use and water quality.
Although Green Valley is now on the list of lakes in the maintenance stage of restoration, Carr said the work is never done.
“I think you should always be looking for opportunities to make improvements in your watershed. That’s an ongoing practice and partnership,” he said, citing hopes for further work with landowners, more plant growth in the lake, and perhaps fewer algae blooms.
This IowaWatch story was published in the Iowa City Press-Citizen and The Hawk Eye (Burlington, IA) under IowaWatch's mission of sharing stories with media partners. To learn how IowaWatch's nonprofit journalism is funded and how you can support it, go to this link.