Skiing, swimming, and wading continue to be banned at Marion Reservoir because of toxic blue-green algae.

Kansas Department of Health and Environment renewed its warning Thursday on the basis of tests performed Monday.

The warning has been in effect since June 28. A less serious advisory had been in effect May 31 through June 21.

Under a blue-green algae warning, many reservoir facilities remain open even though beaches are closed.

KDHE recommends that if reservoir water contacts human or animal skin, the area should be washed with clean drinking water as soon as possible.

Fish caught during an outbreak are safe to eat if they are rinsed with clean water and if only the fillet is eaten, KDHE advises. Anglers should wash their hands with clean water after handling fish caught during an outbreak,

Other lakes with blue-green algae warnings are Herington Reservoir, Dickinson County; Logan City Lake, Phillips County; and Memorial/Veterans Lake, Barton County.

Lakes on less severe blue-green algae advisories are Lovewell Reservoir, Jewell County; South Lake, Johnson County; and Brown County State Fishing Lake.

Blue-green algae, which also can be reddish purple or brown, are simple, naturally occurring aquatic plants — technically, bacterial plankton, not algae. When nutrient and light levels are especially high, they reproduce rapidly in what is called a bloom creating what often is referred to as “pond scum.”

Some blooms are harmless and merit no warnings, but others potentially contain toxins that can be released when the blue-green algae are killed. Toxins vary with the species of blue-green algae. Most have relatively minor effects, but some — such as anabaena — can be lethal.

Health effects occur when surface scum or water containing high levels of toxins are swallowed, contact the skin or are inhaled as airborne droplets.

Most people have “allergic”-type reactions such as intestinal problems, respiratory problems, or skin irritations. However, symptoms of the extremely fast-acting neurotoxin can include coordination loss, paralysis, muscle twitching, shortness of breath, and even death.

Marion, Hillsboro, and Peabody all get their drinking water from Marion Reservoir. Costly improvements at treatment facilities make it highly unlikely that neurotoxins from a bloom can make their way into municipal drinking water.