The Grand River Dam Authority is reporting that its most recent monitoring has confirmed there continues to be the presence of a blue green algae (BGA) bloom in Grand Lake’s Horse Creek area. Due to the current conditions, GRDA continues to advise the public to use extra precaution in this area of the lake as the bloom can concentrate as it is pushed by the wind and waves.

Most recent testing by GRDA shows the Horse Creek bloom varying in toxin levels from 5 micrograms per liter (ug/l) to >20 ug/l. Environmental Protection Agency (EPA) guidelines, published in 2019, recommend no primary body contact with the water when microcystin concentration produced by the BGA is greater than 8 micrograms per liter (>8ug/l).  The areas of highest toxin are scums that can form quickly and tend to congregate along shorelines and docks.

At this time, GRDA’s ongoing monitoring suggests that the Horse Creek bloom remains the primary area of concern and will continue to monitor for additional blooms throughout the lake.

“We are always committed to the safety of the public. We want the public to be aware of this situation and any issue that could impact public safety. We also want residents and visitors to know the overwhelming majority of Grand Lake does not show any signs of BGA and is ready for visitors to come and enjoy this weekend,” said GRDA Executive Vice President of Corporate Communications, John Wiscaver. “We will continue with our daily testing and surveys at Grand Lake. Conditions can change rapidly, and we will continue to provide public updates as needed.”

BGA may resemble thick pea soup, green paint or bluish, brownish, or reddish-green paint. When BGA washes up on shore, it can form a thick mat on the beach. BGA can reproduce rapidly in water bodies with adequate amounts of sunlight and nutrients such as phosphorous and nitrogen. It is recommended that individuals avoid swimming or participating in water recreational activities in areas where the water is discolored or where you see foam, scum or mats of algae on the water.

If you see a BGA bloom, ODEQ recommends that you avoid all contact with the water, keep your pets and livestock away from the water and immediately contact ODEQ at (800) 522-0206 or GRDA at (918) 256-0911.

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