UPDATED: Toxins force rare reservoir closure; lake also under warning
In a rare, possibly unprecedented move, Marion Reservoir was closed to all visitors Thursday after tests revealed an extremely high level not only of blue-green algae but also of potentially deadly toxins they release.
The next day, Marion County Lake was placed under the second most serious algae advisory, a more familiar "warning." The county lake will remain open, but visitors are being warned not to come into contact with lake water.
At the reservoir, barricades were erected Thursday, and park rangers traveled to all picnic areas, campgrounds, boat launches, and swimming areas to instruct visitors to leave, lake manager Brock DeLong said.
“People are understandably very frustrated,” he said.
Relatively few people were at the reservoir when its closure was ordered, but a “decent amount” of reservations for the weekend have been canceled as well, DeLong said.
The reservoir, just beginning its most popular period of visitation, is likely to remain closed to all visitors for a week. All campsite deposits through June 9 are being refunded.
The “hazard” level ordered Thursday by Kansas Department of Health and Environment is the highest of three advisories issued for blue-green algae and is used only rarely, KDHE spokesman Matt Lara said.
“It doesn’t happen very often,” Lara said. “The last time anyone in the state reached that level was probably back in 2017 and for just a short time.”
The reservoir and lake won’t be tested again until Monday, and results won’t be available until the Thursday after that.
Lara said his information did not include a complete list of which of several toxins produced by blue-green algae, technically called cyanobacteria, were present in reservoir water. Some are relatively harmless, causing little more than skin irritation in humans. However, some are potentially lethal neurotoxins that worldwide have led to the death of animals and, in isolated cases, humans.
He did say that cyanobacteria in the reservoir were releasing microcystin, a potent liver toxin and possible human carcinogen. Cyanotoxins like microcystin can kill livestock and pets that drink affected waters. Fish and bird mortalities also have also been reported in bodies of water with persistent cyanobacteria blooms.
There was no indication whether the most dangerous of the cyanotoxins, a neurotoxin produced by the anaboena strain of cyanobacteria, was found in the water.
“We wanted to get a hold of this as quickly as we could,” DeLong said.
Officials worry not only about touching or drinking reservoir water but also about breathing in air containing aerosolized water from boats or skiiers. That’s why the entire reservoir was closed to all forms of recreation, even picnicking.
For the past 18 years, the reservoir and lake frequently have been under blue-green algae warnings or watches, but this appears to be the first time since KDHE started announcing algae advisories that the entire reservoir has been closed.
Much of Marion County’s drinking water comes from the reservoir. However, waterworks operators say that new equipment installed at water treatment plants in Marion and Hillsboro after blue-green algae initially appeared removes potential toxins, keeping drinking water safe.
At the county lake, a warning was issued Friday. The lake isn't being closed, but visitors are being advised to avoid all contact with lake water and to wash with clean water as soon as possible if lake water does contact their skin.
Livestock and pets should be prevented from drinking lake water, which humans should never consume regardless of blue-green algae status.
Fish caught in the lake still may be eaten, but only if they are rinsed with clean water and all but the fillet portion is discarded.
Both the more serious "hazard" status at the reservoir and the second-level "warning" status at the county lake are based on testing performed on Memorial Day, when both bodies of water were jammed with visitors. To date, no reports of illness among Monday visitors have been released.
Nearby, Herington City Lake also was added to the "warning" list Friday.