SHERIDAN — Summer brings warmer temperatures and its associated positive and negative effects. One of those negative aspects is the increased danger in some bodies of water caused by potentially dangerous algae.

Cyanobacteria, also called blue-green algae, can form harmful algal blooms that cause skin irritation, organ damage and in severe cases, death for both humans and animals. HABs usually occur in late summer and early fall in slower-moving bodies of water like ponds and lakes.

Lindsay Patterson, supervisor for the Wyoming Department of Environmental Quality surface water quality standards program, said the algae issue is a fairly recent one in Wyoming. DEQ began seriously taking a look at HABs in 2013 and has been working with several organizations over the past few years to study and improve responses to the problem.

“As the science improves and we learn more and more, there’s just a much better understanding of the potential health risks associated with some of the types of blooms that can happen,” Patterson said.

Patterson said the blooms occur in late summer and early fall because the algae needs time to grow. Once temperatures decline, the prevalence of harmful algae will as well.

“A lot of times you have potentially more nutrients coming in during irrigation season, or the water temperatures begin to increase,” Patterson said. “It just takes a while for them to kind of get going, so usually we don’t see them get really bad until July or August.”

HABs are usually caused by excessive amounts of nitrogen and phosphorous. The two components are essentially fertilizer for algae and could come from stormwater or runoff from a nearby yard or golf course.

“Once it rains, the nutrients can wash off into the surface water and potentially make these algal blooms grow,” Patterson said. “[HABs] occur at low levels and when you add more nutrients than the system is used to, they just proliferate and grow kind of crazy.”

Potentially harmful blooms should be reported to DEQ’s Report a Spill hotline at or (307) 777-7501. After receiving a report, a DEQ employee takes water samples, which are analyzed in a lab to determine the density and quantity of toxins in the water. Patterson said it usually takes about 24 hours to get preliminary analysis on the water.

If the toxin quantity and/or density exceeds a certain threshold, DEQ notifies the Wyoming Department of Health, which then notifies local water management agencies that are responsible for posting advisory signs.

There were three reports of cyanobacteria in Wyoming last year and two confirmed. One occurred in Boysen State Park in Shoshoni, which had both toxins and cell density that exceeded thresholds. Another confirmed report took place in Woodruff Narrows Reservoir near Evanston, where bacterial cell density exceeded its threshold. A report in Flaming Gorge National Recreation Area near Rock Springs had below-threshold levels.

Algae threats appear to be minimal in the Sheridan area.

“It doesn’t look like there’s too much happening in the northeast corner of the state,” Patterson said. “I don’t know if that’s just a lack of data or because there’s not many larger reservoirs that are visible on satellite imagery.”

There haven’t been any reports yet in 2018, but Patterson expects to respond to more reports this year because of the increase in monitoring resources.

Dr. Alexia Harrist, state health officer and state epidemiologist with the Wyoming Department of Health, said side effects range from a minor annoyance to severe health issues. Direct contact with toxic water can cause rashes, irritation of the eyes, nose and throat and respiratory issues. Ingestion of affected water can lead to headaches, abdominal pain, vomiting, confusion and numbness, diarrhea and liver and kidney damage.

There are no truly preventative measures other than avoiding and reporting HABs. The toxins cannot be removed through boiling, filtration or chlorination, either. DEQ and other agencies are working on reducing HABs but are still in the beginning phases of addressing them.

Harrist noted that campers should not wash clothes or dishes in potentially dangerous water and added that water skiing and tubing can cause potentially harmful water to spray into a person’s face.

Harrist said WDH has not received any human injuries as a result of HABs but has been informed of livestock injuries and deaths in recent years. Like Patterson, Harrist is not sure if HABs are becoming more common or if more attention is being paid to them.

Summer is a time for outdoor fun, but recreaters must remain aware of potential harm in bodies of water around the state.