Berkeley gets $4M to help clean Aquatic Park’s polluted lagoon and stop I-80 from collapsing

Failing, 100-year-old tidal tubes connect the Aquatic Park lagoon to the San Francisco Bay below Interstate 80. Credit: Ximena Natera, Berkeleyside/CatchLight Local

The cliché “third time’s the charm” proved true for Berkeley’s efforts to fix the aging culverts connecting the Aquatic Park lagoon with the San Francisco Bay. 

Berkeley received a $4.1 million state grant last month after trying twice before in recent years for funding to repair or rebuild the deteriorating 100-year-old tubes running under Interstate 80, said Scott Ferris, head of the city’s parks and waterfront department. 

Prone to cracking and clogging, the failing tubes are believed to be primary culprits for the lagoon’s chronic pollution, as they’re less and less efficient in channeling bay water in and out of lagoon with the tides, a cleansing action. 

Of particular concern are the lagoon’s periodic but persistent high rates of enterococcus bacteria, a health risk for humans, and marine die-offs, primarily affecting rays and leopard sharks. 

Also alarming, city engineers believe tube failure could trigger failure of the freeway above.

“This is one of the highest priority projects in my department,” Ferris said. “There are a lot of factors here that make this a really high priority to fix. We’re so excited.”

The project is expected to repair or replace culverts in two locations at Aquatic Park. Credit: City of Berkeley

The grant is from the California Transportation Commission’s local climate adaptation program.  It’s matched with $800,000 from Berkeley’s general fund, approved by the City Council last year, for a total project pot of $4.9 million. 

The work, slated to take a few years, will renovate or rebuild eight tide tubes, five from the lagoon’s main northern section to the bay, two from the smaller southern portion, and one that connects the two.

The 24-inch diameter tubes, most of which are clay, will either be replaced or sleeved, essentially inserting new culverts into the old ones, depending on what engineers decide after further study, Ferris said.

The system is also key in draining stormwater from most of central and southern Berkeley downhill into the bay, with 14 storm drains emptying into its waters. The lagoon serves as an  important storm basin, Ferris said, though this function is controversial in city history, with some residents saying it was never designed for drain runoff.

The precise timing of the project is impossible to predict, Ferris said. “We just don’t know until we get into it.” 

City officials encourage people to limit contact with the water in Aquatic Park’s lagoon. Credit: Ximena Natera, Berkeleyside/CatchLight Local

Environmental permitting and assorted bureaucratic work could take a year or two, then construction. Ferris said the entire project could be completed by 2030, which is also when the city estimates the culvert system could start to fail.

The work will require a California Environmental Quality Act (CEQA) review, and may need a National Environmental Policy Act Review (NEPA), since the state funding includes some federal dollars.

Despite rapid changes in federal government, including at the US Environmental Protection Administration (EPA), which administers NEPA, Ferris said he’s been told the city funding is secure. “We’re being told that our money is solid.”

The work isn’t expected to disrupt freeway use, he said.

Tide tubes main suspect in shark and bat ray die-offs and enterococcus spikes

A dead leopard shark spotted in Aquatic Park in 2023. Credit: Citizen reporter

The lagoon, a mile-long artificial waterway stretching between the Southern Pacific railway tracks and Interstate 80, was built between 1935 and 1937 as a centerpiece of the new Aquatic Park.

In its early days, it was the scene of festive model boat races, and small sailboats. In recent generations, it’s used for kayaking, canoeing, and water skiing. 

Over the decades, as the park went through ups and downs tied largely to city investment, the lagoon became prone to sedimentation, or filling in, and pollution, especially enterococcus bacteria, a health hazard associated with feces from warm-blooded animals and humans.

Lagoon enterococcus levels, monitored by the city, have intermittently exceeded the state’s healthy level for years, primarily in rainy weather. 

The lagoon has also been the site of periodic marine die-offs, mainly affecting sharks and rays.

After a particularly concerning enterococcus spike in 2018, with unusually silty and stinky lagoon water, the city launched an investigation, which led to some urgent tide tube maintenance, clearing out muck and hardened tube worm casings.

This work made a difference, said Ferris, and lagoon users have noticed. 

Sedimentation has decreased, and data shows an overall downward trend in lagoon enterococcus levels, though they still spike after rainfall. Positive changes are most pronounced in the larger northern lagoon.

Aquatic Park activists say tide tube fix would be boon to fish and seabirds

A sign in the southeast entry of the park lets users know the current water quality in the lagoon. Credit: Ximena Natera, Berkeleyside/CatchLight Local

The improved health of the lagoon since recent city tube maintenance is important, Ferris said. But it was always viewed as temporary, given the disintegrating state of the tubes.  

The problem is aggravated by climate change, he said, with projections of increased rainfall stressing storm infrastructure, and sea level rise further stressing the tide tubes. 

David McGuire, founder and executive director of Shark Stewards, a Berkeley-based nonprofit focused on saving endangered sharks and rays by protecting habitat, said, “This is exciting news for the water quality of Aquatic Park and the health of the marine life in the lagoon.”

McGuire, who is also a member of Friends of Aquatic Park, said, “We are looking forward to seeing fish and seabirds flourish in the improved conditions.”

Last year, Shark Stewards, which works internationally, launched an Aquatic Park Stewardship program with support from the UC Berkeley Chancellor’s community fund. 

The program involves cleanups, water quality testing, invasive plant removal and more, primarily done by UC Berkeley undergraduates. Program partners include Cal, the city, the East Bay Regional Park District, and the nonprofits Friends of Five Creeks, East Bay Disc Golfers, Waterside Works and the Berkeley Paddling and Rowing Club. 

“The water quality data we are collecting. . . will provide a valuable baseline to compare the improving conditions once the new tubes are in place,” McGuire said. 

Other city efforts in the works to clean stormwater

Meanwhile, another city project aimed at improving lagoon water quality is progressing, Ferris said. 

In-the-works design plans for upgrades of Dreamland playground, located on the northeast corner of Aquatic Park, will include details of a bioswale and two hydrodynamic storm drain separators, “green technology” designed to clean storm runoff before it reaches the lagoon. 

The infrastructure, which is already funded primarily from an 2023 EPA grant, will be located adjacent to Dreamland.

The bioswale, a vegetative or planted depression that collects and cleans stormwater, is planned for the parking lot at the bottom of Channing Way. One separator, which uses gravity to sieve and divert debris from stormwater, is slated for the Channing storm drain and the other for the Bancroft Way drain, both of which end at the park.

“We’re almost done,” of the plan, Ferris said. “In a perfect world, bioswale and hydrodynamic separators will be installed in the next 16-18 months.”