Oakland

Oakland Nonprofit Fundraising to Help Lake Merritt Avert Another Fish Die-Off

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The Lake Merritt Institute, a nonprofit that helps to clean and monitor the health of Lake Merritt in Oakland, says the recent rains in the Bay Area have sent lots of fresh water and pollution into Lake Merritt.

The weather-related changes have also stoked fears that the fish die-off in the lake last summer could repeat this summer. The Lake Merritt Institute is ramping up fundraising efforts in hopes of curbing conditions that could fuel a repeat die-off.

In the summer of 2022, thousands of dead fish washed up in Lake Merritt as a "red tide" algae bloom spread in the lake and across the surrounding San Francisco Bay. At Lake Merritt, visitors reported strong smells from all the dead fish, and crews had to scoop the dead fish up and out of the water. Visitors reported seeing striped bass, top smelt, crabs, and even bat rays among the dead wildlife.

A photo of dead fish washed up in Lake Merritt during the algae bloom in the summer of 2022. Photo Courtesy: James Robinson.

James Robinson, executive director of the Lake Merritt Institute, explained that these algae multiplied, starving the lake of oxygen, which killed off the fish. Robinson said small algae blooms had occurred in Lake Merritt before but never to the extent seen in 2022.

The Lake Merritt institute says Lake Merritt is technically a tidal lagoon, not a lake.

"Most people don’t even know that this lake is connected to the bay,” Robinson noted.

Lake Merritt contains a mix of saltwater and fresh water. Oaklandside recently reported that the inundation of fresh water from recent rains has reduced salinity levels in the lake in ways that could harm organisms that are used to living in a mix of fresh and saltwater.

During winter in the Bay Area, Robinson said there are fewer algae in the lake. The water is no longer the tea-red color it was last summer during the height of the bloom. But he explained that rains in the Bay Area over the past several months are presenting new challenges.

Robinson noted that all the fresh water from the rain can lead the water in the lake to separate, with fresh water usually remaining higher up and the layer of saltwater falling below.

"The top level has a fair amount of oxygen in it, and if we have low, dissolved oxygen on the bottom level which is salt, the fish can't get up to breathe, and sometimes we can have fish pass away due to low, dissolved oxygen," Robinson said.

Additionally, Robinson said the storms have flushed more pollution and trash into Lake Merritt.

"So we gotta make sure we are on top of it, so that the pollution is not affecting the wildlife," Robinson continued, adding that the nonprofit is continuing its weekly cleaning efforts at the lake.

The Lake Merritt Institute says the city of Oakland is working on a pilot project that will help to oxygenate the lake. In the meantime, the institute is fundraising for several things to help the lake immediately.

The Lake Merritt Institute has a goal of raising $150,000 to get more staff out to Lake Merritt and to install four aerators that can improve oxygen access for fish.

Robinson said he is hoping a second algae bloom doesn't happen at Lake Merritt this summer, but he admits the thought keeps him up at night.

"If the environment was the same as it was last summer, there is a high potential,” he said. 

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