Jackie Krentzman is a Bay Area-based writer and editor. 

Dustin Thompson has been running along the shores of Lake Elsinore several times a week for the past eight years. Over time, he noticed the water getting murkier and murkier. Then, about a year ago, he was able to see aquatic life under the water’s surface.

“It was so sad to see the water quality go downhill,” he says. “So, it has been wonderful to see the sizable improvement in the water quality over the last year or so.”

The water clarity Thompson noticed is the result of years of concerted effort by the city of Lake Elsinore. Climate change has significantly warmed the largest freshwater lake in Southern California, causing toxic algae blooms and health advisories for humans and pets. In recent years, the city began exploring ways to restore its crown jewel that once attracted Hollywood celebrities like Steve McQueen.

Like many freshwater lakes in the U.S., the lake’s water quality has long been an issue. The 3,200-acre lake landed on the state’s imperiled body of water list in 1994. Then, in the mid-2010s, the water quality declined even more dramatically, as temperatures and flooding increased. In 2018, hundreds of tons of fish began dying off due to toxic algae and the death of healthy bacteria.

Lake Elsinore’s shallow waters make it especially susceptible to warming waters. It also sits at the terminus of the San Jacinto watershed: Water flowing from upstream rivers and lakes has nowhere else to go. The city tried a few solutions to clean the water, such as aerification and destratification systems. But none made a lasting difference.

In 2022, the city found the solution, says Community Support Manager Adam Gufarotti.

“That year, the toxin levels got so high we had to close the lake to the public for six months,” he says.

The city and regional partners explored four different techniques that could clean the lake’s water. Ultimately, they chose nanobubble technology — microscopic bubbles 2,500 times smaller than a grain of sand. These tiny bubbles inject oxygen and healthy ozone into the lake, increasing oxygen levels and reducing the conditions that lead to harmful algae blooms. In 2023 the city council invested $2.6 million and passed a comprehensive lake management plan.

In early 2024, the city bought a barge carrying a machine that takes the ambient air, compresses it into pure oxygen, and injects it into the water through the bubbles. The city also installed five monitoring buoys around the barge that provide real-time water quality data, including temperature, oxygen levels, and the water’s ability to clean itself.

The effort is paying off. By all measures, including visibility and oxygen levels, the lake’s water quality has improved significantly. In late 2024, Lake Elsinore received a $1.5 million matching grant from the California Department of Water Resources to purchase two more barges that became operational last fall.

“Oxygen in the water column is really important for our aquatic life,” says Gufarotti. “Nanobubbles are so effective because they are naturally buoyant and stay in the water columns longer, plus drift all the way down to the bottom of the lake.”

The changes are having a big impact on the local economy. Lake Elsinore was developed in the 1930s as a vacation getaway for Hollywood celebrities. The area, which has a large network of hot springs, also boasts several resorts. The lake was so central to the city of Elsinore’s identity and economy that residents voted to change its name to Lake Elsinore in 1972.

But as the lake declined, tourism did as well. During the six months the lake was restricted in 2022, the city lost $300,000 in direct revenue, such as permits, parking, and boat launch fees, and more in lost hotel, restaurant, and shopping dollars.

Today, the lake and city are once again a center of regional tourism. On the weekends, picnicking families, swimmers, fishers, boaters, and jet skiers pack the area. In 2019, the city completed a $19 million revamp of the popular Launch Pointe campground and facility. Launch Pointe boasts a restaurant, large event venue, and campground where guests can bring their own RVs or rent a restored vintage trailer or a glamping yurt.

“This cutting-edge technology has been a lifesaver for the lake and city,” says Mayor Brian Tisdale. “It has restored the water quality of this Southern California jewel and revitalized the city’s economy. We look forward to the continuing improvement in water quality in the years to come.”

The lake’s swift turnaround attracted national and international attention. In 2024, the city and Moleaer Inc., the company that provided the nanobubble technology, hosted a global water summit to demonstrate the technology to other cities and private companies in the United States, Canada, and South Africa.

“Lake Elsinore is once again a great amenity for the entire area,” says Thompson. “The city is proud of the lake — it is part of who we are.”