With temperatures reaching into the 100s one afternoon last month, Ron Madson noticed a green slick forming around the docks he operates on Utah Lake, signifying the start of a toxic biological event that, in the past, would have shut down the Lindon Marina.

But this year, the marina along with two others on Utah Lake are the sites of a new treatment program testing various strategies for knocking down harmful algal blooms that explode every summer on many Utah lakes. With eight hours of chemical treatment, Madson said, a bloom at Lindon Marina was gone.

“It absolutely knocked it out. Every indicia of the bloom was gone,” he said. “Had they not treated it, it could have gone on for an indefinite time and generated negative publicity.”

Since 2016, these events have become particularly severe on Utah Lake, thanks to climate change, low water and excessive nutrients from agriculture and wastewater treatment plants. Recent treatments at Utah Lake marinas have shown promise, but state officials remain hesitant to embrace chemical treatments in the war on algal blooms. Their emphasis is on prevention.

Algae and phosphorous aren’t necessarily bad for lakes, but blooms of green-blue cyanobacteria result in dangerous concentrations of their toxic byproducts that cause neurological damage, skin irritation and gastrointestinal distress. These episodes are most acute during hot spells, like those Utah has been sweating through since early July.

When Madson observed a bloom forming at Lindon Marina on July 28, he called ATS, one of two firms state officials have contracted to conduct the anti-algal treatments.

A crew arrived at 2 p.m. and applied 34 gallons of a copper-sulphate-based algaecide called EarthTec. That night, the marina was largely clear of algae, the water returned to its normal color and the marina was able to safely resume operations the next day, according to Madson.

ATS conducted follow-up treatments using increasing amounts of EarthTec on July 30 and Aug. 4. The Murray-based firm’s CEO Richard Allred contends the treatments work and the program should be expanded to cover the entire 95,000-acre lake.

“We have witnessed the frustrations and economic struggles these toxic algal blooms have caused, especially when beaches and marinas have been forced to close over these past few summers,” Allred said. “We know that ATS’ solutions will provide a safe water treatment solution for Utah Lake, and we are eager to expand our testing program to more affected areas on the lake.”

Addressing lawmakers at last week’s interim meetings, however, state environmental officials said it was too early to declare the Utah Lake treatments a success.

“We really have to wait until they are completed before we can have any opinions,” said Brian Cottam, director of the Division of Forestry, Fire and State Lands.

Health advisories have remained in place on Utah Lake, both on its open waters and east shore marinas, since July, despite the treatments at three marinas, according to Erica Gaddis, director of the Utah Division of Water Quality.

“The fact that we are continuing to have advisories there is a bit of a concern,” Gaddis said. “We will have to dissect the data from those treatments at the end of the season to see what’s going on. It appears there may be some good temporary benefit. We have to see how long those benefits extend in those marinas.”

To pay for the $500,000 treatment program, Utah lawmakers had defunded the division’s monitoring program, which hamstrung the state’s ability to track algal blooms.

The Department of Environmental Quality backfilled the program’s funding with a $100,000 federal grant, enabling it to resume monitoring for a year on at least 18 of the 60 lakes previously covered. Gaddis cautioned that monitoring is central to the success of the state’s efforts to control algal blooms. Without monitoring to detect blooms and studies to identify their root causes and triggers, treatments would provide only fleeting improvements.

“We have to be able to get out and see what’s happening in the waters,” Gaddis said, “in order to provide good information to the public in real time and to evaluate the effectiveness of treatments.”

The other company involved with the treatments, SePRO Corp., headquartered in North Carolina, was assigned to tackle Lincoln Marina, considered Utah Lake’s worst algal hot spot. Treatments in June beat back blooms but only for a day or two before prevailing winds would push the cyanobacteria from the lake’s main body into the 3-acre marina, according to Eric Ellis, executive director of the Utah Lake Commission.

So, in July, that project was moved to Utah Lake State Park, which hosts a popular marina on the lake’s Provo shore. SePRO’s treatments deploy a suite of products, including an algaecide. Another chemical reduces the bioavailability of nutrients suspended in the lake water, effectively starving the algae. These treatments, which occur about every other week, are tailored to specific conditions on the marina, according to Ellis.

“They definitely showed great success, but not without issues coming up. A treatment like that could be helpful in a Band-aid-type approach on a big bloom that hits before a popular holiday, like Labor Day when we would like to see the lake free of algal blooms,” Ellis said. “It is unlikely this would be the long-term approach for blooms on Utah Lake.”

In other words, algal blooms aren’t the disease but a symptom of a larger malaise that must be addressed if the lake’s ecology is to be saved.

Allred contends treatments provide relief and can buy time while more permanent fixes are engineered. The algaecide ATS uses is not harmful to most other aquatic organisms, yet it has shown to be effective against quagga mussel, an invasive mollusk spread by boaters and plaguing many Western lakes

The chemical spreads across the surface of the water, where the cyanobacteria congregates, but only penetrates to a depth of 1.5 meters, Allred said. Because it disperses quickly, its effect on the ecosystem is short-lived.

He believes the algaecide, which costs $22 a gallon, could be deployed across Utah Lake for as little as $1.5 million a year. The idea would be to target blooms as they form, limiting their spread and even preventing toxic plumes from entering the Jordan River.

“This could be funded privately,” Allred said. “The real issue is, are we going to wait till the lake is dead or do we deal with it now? We can do it. We have the technology, and it’s financially feasible, but mostly it’s the right thing to do.”