The Grand River Dam Authority is reporting the presence of a blue green algae (BGA) bloom in the Horse Creek arm of Grand Lake. Water quality testing performed over the weekend by the GRDA Ecosystems and Watershed Management Department confirmed the bloom, extending from Fly Creek (which feeds into Horse Creek) and then out under the Bernice Bridge into the main lake.

Although its testing has confirmed that toxicity levels in this BGA bloom remain low, GRDA is advising the public to use extra precaution in this area of the lake as the situation can change rapidly and the bloom can concentrate as it is pushed by the wind and waves. 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 eight micrograms per liter (>8ug/l). GRDA’s latest sampling shows the toxin level in Horse Creek at less than one microgram per liter (<1ug/L).

“While most algae blooms are not toxic, toxins can be produced in some algae blooms dominated by Blue Green Algae,” said GRDA Vice President of Corporate Communications Justin Alberty. “We have communicated these test results to the Oklahoma Tourism and Recreation Department, the Oklahoma Department of Environmental Quality, and the Oklahoma Water Resources Board. Right now, we are closely monitoring the area and will provide regular updates as the situation progresses.”

“However, Grand Lake is plenty big, with room for the public to come out and enjoy. We just encourage everyone to play safe and please be aware of the BGA report for this specific area.”

According to the Oklahoma Department of Health, exposure to BGA can cause skin irritation, including rashes, hives or blisters. Inhalation of BGA can also trigger asthma-like conditions or allergic reactions. Finally, ingestion of BGA water can cause stomach cramps, nausea, diarrhea, or vomiting. Due to their body size, young children are especially susceptible to the effects of BGA. It is also important to keep pets from drinking and swimming in water containing BGA water.

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.

Municipalities that draw raw water from this area should be taking the necessary steps to ensure the quality of their water by utilizing their water treatment systems, and lake residents who draw water from this area should avoid consumption of and contact with the water until further notice. Simply boiling water that may contain BGA does not remove the toxins from the water.

Since a large BGA outbreak across Grand Lake and many other Oklahoma lakes in July 2011, GRDA has increased its focus on programs to improve water quality in the Grand Lake watershed, to limit the inflow of nutrients that help fuel BGA.

In late 2020, GRDA announced it was leasing 237 acres along Horse Creek to be established as a natural riparian easement. When managed properly such areas can filter as much as 80 percent of pollutants before they runoff into creeks or streams.

Earlier this year, GRDA also joined with the Oklahoma Conservation Commission (OCC), the Oklahoma Department of Environmental Quality (ODEQ) and the Oklahoma Water Resources Board (OWRB) in a program to offer septic system repair or replacement assistance to homeowners in the Grand Lake and Lake Hudson watersheds. Additionally, GRDA’s “Guard the Grand” watershed conservation program also launched in 2020, to help educate area residents on issues surrounding the Grand Lake watershed and how they can play a role in helping to improve area water quality.

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.