The Fountain by Lake Merritt's Pergola Was Always an Experiment. What Comes After It?

At a public meeting about Lake Merritt on August 4, 2026, Lake Merritt Institute founder Richard Bailey brought an inexpensive aquarium bubbler. According to the Lake Merritt Institute's account of the meeting, he held it up every time he spoke. "You can't dredge the lake for a million, you don't have the money," he told the room. "But you could put in a lake wide bubbler system."

The bubbler was a prop, but it got to the real question. If you've walked past the Pergola at El Embarcadero in the last three years, you've seen a working version of the same idea. That spray of water off the shoreline is an aeration fountain, and it's one of two devices in a city pilot program that ends on December 31, 2026. The other device didn't work. What the city does next is still open, and the reason it's open says a lot about how the lake actually works.

Why There's a Fountain There at All

The pilot started because of the 2022 Lake Merritt fish kill. A previous investigation traced that die-off to a bloom of the algae Heterosigma akashiwo, which pulled dissolved oxygen low enough to suffocate fish across the lake.

Oakland responded with the Lake Merritt Water Quality Management Pilot Project. The program has three parts. It monitors oxygen levels, it puts equipment in the water to raise oxygen in specific spots, and it works out how to respond when a harmful bloom shows up. Two devices went in during 2023:

• The aeration fountain, installed August 15, 2023, near the Pergola by El Embarcadero. It replaced an out-of-service fountain in the Glen Echo arm. It mixes air into the water to keep an oxygen-rich refuge for aquatic life close by, and the city says its design and spray settings were chosen to maximize benefits to wildlife.
• A bottom oxygenation system, installed in September or October 2023 near where Glen Echo Creek enters the lake. It pumps oxygen in from the lake floor. The city says it "has not worked as expected" and has been modified several times, and that this type of device wouldn't be effective in other parts of the lake.

At the August meeting, the city's Terri Fashing of the Watershed and Stormwater Management Division was more direct. The Lake Merritt Institute reported her saying the hypolimnetic oxygenation system had failed. The system was designed for fresh water and was running in Lake Merritt's salty water. The same report says officials hadn't yet decided whether a separate oxygen device was effective, and that the city and its contractor, LakeTech, were preparing a final report on the two measures.

The Oxygen Problem Lives at the Bottom, and in the Arms

The saltwater detail matters because Lake Merritt is a tidal lagoon connected to the Bay through the Lake Merritt Channel. It isn't a freshwater pond. The San Francisco Bay Regional Water Quality Control Board's October 2025 analysis of continuous oxygen records through March 2025 found that 5.6% of combined samples fell below the state's 5 mg/L objective. The low readings weren't spread evenly. Bottom water dropped below the line 9.8% of the time, compared with 2.3% at the surface, and the Glen Echo and Trestle Glen arms were more prone to low oxygen.

That pattern explains why a bottom oxygenator in the Glen Echo arm looked like a sensible bet in 2023. The problem was in the deepest water in the most vulnerable arm. The device's trouble came from the salt. Where it was placed made sense.

The lake hasn't had a repeat of 2022. It has had smaller scares. On June 4 and June 7, 2025, the Water Board documented two localized die-offs tied to brief low-oxygen episodes. It estimated up to 1,000 organisms were affected, mostly shrimp, and called the events distinct from the prolonged, lake-wide die-off of 2022. Water resource control engineer Gerardo Martinez told the Lake Merritt Institute that the 2025 events were "localized near the docks and the bird islands," and that monitoring stations showed the lake bouncing back. The Water Board's report on those June events credits volunteers from Rotary Nature Center Friends and the Lake Merritt Institute with reporting what they saw and taking local oxygen readings.

Over 99% of the Lake's Nutrients Come In With the Tide

This finding changes the debate most. Algae blooms feed on nutrients, and the natural assumption is that those nutrients wash in from the neighborhoods around the lake through creeks like Glen Echo. The Water Board's January 2026 nutrient analysis, built on 2024 and 2025 sampling, found otherwise. Mass load estimates put more than 99% of nutrient inputs as coming from Bay inflows. Nutrient levels in the lake looked more like Bay water than creek water.

The same report found that nitrogen limits algae growth in the lake, while phosphorus is the limiting nutrient in Glen Echo Creek. It concluded that "phosphorous control efforts like Phoslock will not affect primary production in the lake." The Water Board planned to deploy a continuous nitrate sensor in summer 2026 to follow how nutrients move with the tides.

This is why Oakland can't simply scale up a known fix. Most of what feeds a bloom arrives through the channel with every tide, and the most targeted piece of oxygen equipment didn't hold up in salt water. The tools that remain each address a piece of the problem.

Eight Options and Just Under $1 Million

The next phase is the Lake Merritt Healthy Lake Initiative, which the city lists as running from January 2026 through December 31, 2029. It's funded by a federal Congressionally Directed Spending award managed by the EPA, and aeration fountains are among the measures named for evaluation. The State Water Board lists Oakland's award at $959,757.

The August 4, 2026 meeting agenda lists eight candidate measures for a technical advisory committee to weigh:

1. Hypolimnetic oxygenation, the bottom-up approach that failed in the pilot
2. Aeration and mixing fountains, like the one by the Pergola
3. Nutrient reduction
4. Dredging
5. Constructed wetlands
6. Macroalgae removal
7. Tide-gate operations
8. Emergency and rapid-response measures

The committee's memo is meant to recommend actions that are technically and economically feasible. It isn't a final plan. Tide-gate operations stand out given the nutrient findings, since the Bay is where most of the nutrients enter. Emergency response is already partly in place. The Lake Merritt Institute reported that the Water Board has issued Oakland a permit to apply an algaecide during an emergency bloom, which Fashing called "very experimental."

On spending, Fashing was candid, as quoted by the Lake Merritt Institute:

"If we decide that this [monitoring] is the best way to spend some of this million dollars, then that's what we will do."

When Katie Noonan, an Oakland environmental advocate and community water monitor, asked whether some of the money could go to volunteer sampling and youth education, Fashing said the city would seek input from community groups and check whether the EPA and Water Board would agree. The San Francisco Estuary Institute, the Water Board and the technical advisory committee are set to help interpret the data LakeTech collects.

Where Volunteers Fit In

The people already helping are named in the city's own materials. Oakland lists the Lake Merritt Institute, the Measure DD Community Coalition, the Oakland Parks and Recreation Foundation, EBMUD and several regional and federal agencies as partners on its lake water-quality work. The 2025 die-offs were reported first by volunteers on the shoreline. For anyone who walks the lake regularly, these upcoming dates fall in the pilot's last weeks:

• Saturday, October 31, and Tuesday, November 3: Lake Merritt Institute shoreline and water cleanups, 10 a.m. to noon, starting at the Sail Boat House.
• Second Saturdays: Morning Birding & Coffee at the Rotary Natural Science Center.
• Saturday, November 14: A Kayak 101 class through the city's Lake Merritt Boating Center. From November through February, boat rentals run Saturdays and Sundays, 10:30 a.m. to 4 p.m.
• Saturday, October 31: If you're heading to the lake with kids, Children's Fairyland holds Mad Magic!, its Halloween celebration with trick-or-treating, from noon to 7 p.m.

The Lake Merritt Weed Warriors say fall workday announcements are coming. In the meantime they've paused their usual Measure DD garden-bed workdays while they look at other garden sites.

The pilot that put the fountain by the Pergola in place officially ends on December 31, 2026. The Healthy Lake Initiative's spending plan will decide whether fountains like it are part of what comes next, whether the money goes to the tide gates and monitoring, or whether it goes to something else on the list of eight.

At Scott & Scott Real Estate Associates, we follow how Oakland cares for places like Lake Merritt because they're part of daily life here. If you'd like to talk about the lakeside streets or anywhere else in the East Bay, contact us for a personalized consultation.