At about 3:30 in the afternoon on June 4, 2025, Katie Noonan of the Rotary Nature Center Friends saw dead fish, shrimp and worms in the shallows at two spots on the north end of Lake Merritt. One was near the Rotary Nature Center and the other was at the Lake Merritt Boating Center docks. Three days later, at about 12:20 p.m., James Robinson of the Lake Merritt Institute found dead and stressed fish and shrimp at the same docks. Both accounts appear in the opening pages of a San Francisco Bay Regional Water Quality Control Board report on the June 2025 die-offs, which the agency finalized that October.
The two events were small, at most about 1,000 animals, mostly Palaemon shrimp with up to 200 small gobies. In August 2022, by comparison, tens of thousands of dead fish washed up around the lake. The way the 2025 events came to light matters more now than it did then. The City's post-2022 oxygen pilot ends this December, and the plan that replaces it won't produce a recommendation until late 2027. Until then, the best early warning for this lake is a few people and a few sensors working from the Bellevue Avenue shoreline.
The Pilot Wraps Up December 31
After the 2022 fish kill, Oakland started the Lake Merritt Water Quality Management Pilot Project to track dissolved oxygen, install equipment to raise it and respond to algal blooms. The City lists December 31, 2026 as its completion date.
The pilot put two devices in the water, and they had different results.
- The aeration fountain near the Pergola by El Embarcadero went in on August 15, 2023. It replaced a fountain in the Glen Echo arm that had stopped working. It mixes air into the water to keep an oxygenated refuge for aquatic life near the fountain.
- The oxygenation system in the Glen Echo Arm went in during September and October 2023, close to where Glen Echo Creek enters the lake. It pumps oxygen into the water from the lake bottom. The City says it "has not worked as expected" and has been modified several times. The City has also concluded that this type of device would not be effective in other parts of the lake, and it is still evaluating what to do with this one.
So one tool has worked in a small area, and the other one won't be copied anywhere else on the lake.
The Low Oxygen Shows Up in the Arms and Near the Bottom
The Water Board's October 2025 analysis of dissolved oxygen data covers January 2023 through March 2025. It found low-oxygen episodes most often in the Glen Echo and Trestle Glen arms, especially in late summer 2024 and in winter 2025. Water near the bottom fell below the 5 mg/L objective more often than water at the surface.
That pattern explains why the north end needs watching. In June 2025 the readings at the docks fell far below that 5 mg/L objective. Lake Merritt Institute volunteers measured 0.16 to 0.72 mg/L near the Boating Center docks on June 5. On June 7, two nearby sites read 0.63 and 0.12 mg/L, and by June 9 those same sites had climbed only to 1.65 and 1.58. Two of the City's three continuous monitoring stations in the lake also recorded very low oxygen briefly before each die-off. Elsewhere along the shoreline, the water showed normal oxygen and no dead animals.
The first event covered the stretch from just outside the boom near the Pergola fountain to the Boating Center docks. The report ruled out an algal bloom as the trigger for that first event.
"No visible signs of algal blooms or harmful algal blooms (HABs) were present immediately before or after the first fish kill. Additionally, HABs monitoring data confirmed that cyanotoxins were not detected at levels of concern during this period."
The tide gates had been closed for more than ten days and were reopened two days before the first die-off. The Water Board said the data were not enough to connect the gates to the low oxygen, and it planned a closer look at oxygen levels during past gate closures and openings.
Put together, Lake Merritt's oxygen trouble is mostly local, happens near the bottom and can come on fast. The analysis found episodes in late summer and in winter, and the June 2025 die-offs happened without a red tide. Hand-held measurements were what turned "the water looks off" into evidence.
What Replaces the Pilot, on a Slower Clock
The next phase is the Lake Merritt Healthy Lake Initiative. It runs from January 2026 through December 2029 and is funded by Congressionally Directed Spending from the fiscal year 2024 appropriations cycle, with the EPA managing the grant. The City's harmful algae updates page says the grant is nearly $1 million. That money is tied to the Water Board's Advance Restoration Plan work, which is about finding actions that would raise oxygen levels across the lake.
The deliverables list in the August 4, 2026 stakeholder meeting agenda shows how long that will take:
| Step | Scheduled |
|---|---|
| Nitrate sensor monitoring in the lake | July through November 2026 |
| Data analysis and synthesis | March 2027 |
| Draft data synthesis memo | June 2027 |
| Public stakeholder meeting #2 | July 2027 |
| Final data synthesis memo | August 2027 |
| Draft implementation recommendations memo | September 2027 |
| Public stakeholder meeting #3 | September or October 2027 |
| Final implementation recommendations memo | November 2027 |
According to the agenda, the recommendations memo will judge each option by whether it can improve dissolved oxygen across the entire lake and whether it is both technically and economically feasible. The list it starts from:
- Hypolimnetic oxygenation systems, the bottom-oxygen approach tried in the Glen Echo Arm
- Aeration or mixing fountains
- Nutrient reductions to cut algal growth
- Dredging
- Constructed wetlands
- Macroalgae removal
- Tide gate operations
- Emergency and rapid-response measures
Options can be added to the list based on input at the stakeholder meetings. The schedule doesn't say when new fountain sites will be picked. Read alongside the City's verdict on the oxygenation device, that means the summer of 2027 will come before any whole-lake answer does. For the lake's watchers, that leaves one more full year of warm-season risk and one more winter.
The North-End Watch, and Where to Join It
Most of the lake's early warning comes from a small stretch of Bellevue Avenue in Lakeside Park, and there are several ways to take part in November and December.
The Lake Merritt Institute is based at the Sail Boat House, 568 Bellevue Avenue. Its volunteers took the June 2025 grab samples, and its executive director reported the second die-off. The Institute reports 5,706 volunteer hours and about 111,630 gallons of trash removed in 2025. Its 2026 public cleanups meet Tuesdays and Saturdays at 10 a.m., and you need to register ahead of time. The City's events calendar lists free Institute cleanups on Saturday, November 7, and Saturday, November 14, from 10 a.m. to noon. Volunteers use nets and pickers to pull litter from the shoreline and the water.
The Rotary Natural Science Center, a short walk away at 600 Bellevue Avenue, reopened in January 2026 after repairs. It was built in 1953, and the City calls it the oldest municipal nature center in the United States. Hours are Tuesday through Saturday, 11 a.m. to 5 p.m. Morning Birding and Coffee, for ages 18 and up, meets the second Saturday of each month from 9 a.m. to noon, so the next two are November 14 and December 12. A new Nature Journaling series covering the lake's ecology starts Saturday, November 21, and runs from 11 a.m. to 1 p.m. on third Saturdays.
Rotary Nature Center Friends is the all-volunteer nonprofit Katie Noonan represented when she reported the first die-off. Its site links a Lakeside Chat with LakeTech president Eli Kersh called "Oxygen for Lake Merritt - Going forward in 2026," along with a recording of the August 4 stakeholder meeting. The recording is the quickest way to catch up before the 2027 meetings.
The data is public. The City's Lake Merritt water quality page links LakeTech's monitoring portal. The Water Board says LakeTech maintains the City's stations and posts real-time dissolved oxygen readings on its dashboard. Depending on the station, the readings can also include temperature, salinity, chlorophyll-a and turbidity. In June 2025, the station readings lined up with what volunteers saw at the docks.
The Oakland Christmas Bird Count is on Sunday, December 20. Golden Gate Bird Alliance takes volunteer sign-ups for field observers and feeder watchers. The Rotary center sits beside what the City describes as the oldest wildlife refuge in the United States, so a winter morning on the north shore counts as fieldwork.
The pilot ends on December 31, the nitrate readings collected through November feed the analysis scheduled for March 2027, and the next public chance to weigh in on a whole-lake fix is the stakeholder meeting scheduled for July 2027.
At Red Oak Realty, we follow the lake the way people who walk it every week do, from the Pergola fountain to the Glen Echo Arm, and we put part of every transaction back into the community through ROOF. If you'd like a neighbor's read on Lakeside and the shoreline around it, Work with a Seriously Local Agent.
