The North Dakota Department of Health is investigating a possible blue-green algae outbreak at Green Lake, southeast of Wishek.

Health Department spokesman Mike Ell said officials received a report of possible blue-green algae near the boat ramp and swimming area at Doyle Memorial Park, which is adjacent to the lake.

A staff member was in the area last week to test the water for the presence of microcystin.

While awaiting test results, the Wishek Park Board, which operates Doyle Memorial Park, posted warning signs about this year's possible outbreak.

"Earlier this afternoon, I received the result from the sample that was collected on Monday from the boat ramp," Ell said in a Friday evening email.

"While the concentration is relatively low, it is still 5.41 ug/L (ppb). (That is) below our threshold for recreational use of 10 ppb, but near EPA’s new draft threshold of 6 ppb.

"We also collected a sample from the swimming beach area that is being analyzed for three other cyanotoxins besides microcystin. The analysis requires a different method and therefore the results won’t be available immediately.

"Since microcyctin was present in the water, as a precaution I advised the folks down there to leave the advisory signs posted at the lake.

"People should be on the lookout for the algae blooms, which look something like a green or bluish-green paint, or just a coating of scum on the water," Ell says.

"There often is an odor as well."