Changes in water conditions at Aquatic Park in August have led some park users to wonder what’s going on. Photo: John Dye

A huge increase in E. coli bacteria at the north end of Aquatic Park, a lagoon in West Berkeley, has caused the city to urge community members to minimize activities that require contact with the water, the city spokesman told Berkeleyside on Friday evening.

City staff had been keeping a close eye on the water at the park — and stepped up testing from monthly to weekly — following problems that began around Aug. 5-6. Initial bacteria tests in August were well within safety standards, and the city said it would to monitor the situation closely. Friday, however, test results for E. coli levels at the north end of the park — sampled Tuesday — came in at 490 on a scale that puts safe levels at 100, said city spokesman Matthai Chakko.

The bacteria has been associated with a number of high-profile foodborne disease outbreaks linked to spinach, beef and other products. Most strains of E. coli are harmless, but some can make people sick, according to the Centers for Disease Control and Prevention.

Chakko says the city does not know what might have caused the bacteria spike, but planned to post signs Friday night to warn people about the issue. Experts caution that one data point alone should not cause a panic. But the city is still taking the results seriously.

“I’ve never seen it look like this in 30 years of being down there,” John Dye, a member of the Berkeley Paddling & Rowing Club and co-founder of environmental group Rivers for Change, told Berkeleyside this week.

Dye said he was at the park in early August when he noticed a stinky “weird smell” and abnormally high water levels for the season, along with cloudy, tan-colored water that he couldn’t see through.

The water appeared to be about a foot higher than it usually is, he said. City staff confirmed that the lagoon was about 10 inches higher than it had been in August 2018. It’s usually the rainy season that raises the water level in the park. Along with the bad smell and cloudy appearance, Dye was concerned.

He said he contacted city staff who came out to look at the water within 24 hours. The city did not test the water for bacteria levels until Aug. 20, however. By that time, the smell had subsided and the water level had receded, but the water still looked funky, Dye said.

Chakko said the city called for the water to be tested Aug. 16, but that the county lab was tied up until Aug. 20. That was more than two weeks after the initial report to the city. Chakko said the initial report focused only on the water condition and did not include reports of possible sewage. On Aug. 16, he said, the community raised concerns about a possible sewage leak. That’s when the city moved ahead on testing, he said.

When the Aug. 20 test results for the north end of the park came back, they showed some of the year’s highest levels of total coliforms, which are a type of bacteria, along with increased levels of fecal coliforms and E. coli — both of which are subsets of coliform bacteria. (Chakko said the full test results were not available Friday evening when he provided the E. coli number to Berkeleyside. As a result, they do not appear in the table below.)

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Mark Pandori, who runs the Alameda County lab that tested the Aquatic Park water samples for the city, said the Aug. 20 lab results did not indicate a safety concern. None of those numbers exceeded safety thresholds. In addition, the lab results represent one point in time; weekly testing over a longer period would be required to show a public health risk.

The city’s latest results, from this week, were reported to Berkeleyside after business hours, so Berkeleyside was unable to ask the lab about the E. coli numbers or other results.

Public health safety thresholds are set by the Environmental Protection Agency as well as state agencies. Under the BEACH Act, the federal government required states to set bacteria standards by 2004 that would be “as protective of human health” as the EPA’s 1986 standards for recreational waters. (Drinking water has its own rules.) The standard is essentially a threshold under which water is considered safe for recreational contact. Above that standard, there are estimated frequencies for how many illnesses might occur for every 1,000 contacts.

Multiple experts told Berkeleyside the total coliform standard is outdated and can be disregarded because the federal government and other authorities are working to remove it from its regulations.

The park under normal conditions. Photo: John Dye

The State Water Resources Control Board reports that fecal coliform below 200 MPN per 100 milliliters of water should be considered safe for recreational marine waters. (MPN stands for “most probable number” and is a “statistical representation of the results of the standard coliform test,” according to the water board.) Aquatic Park was below that standard in all the Aug. 20 tests.

For E. coli, the standard is 100 colony-forming units per 100 milliliters of water. Above that standard, according to the water board, 32 people are estimated to get sick for every 1,000 “water contact recreators.” As with fecal coliform, Aquatic Park was below the standard in all the Aug. 20 tests.

But those numbers, too, are shifting, as authorities plan to focus more on another test, for enterococci organisms. The standard for enterococci is 30. The enterococci test was not part of the Aug. 20 lab analysis, but Pandori said this is likely to shift in the next year in line with changing regulations.

Community members who have seen the Aug. 20 lab results said they were concerned because some of the results were tagged with an asterisk to indicate that they were abnormal. Pandori said this was an internal flag for scientists to “take notice,” but is no cause for alarm: “It is not at a level where the California standard would consider this water a health risk.”

Again: The lab was closed Friday when the city gave Berkeleyside the new E. coli numbers, which are well above the safety threshold, so Pandori was not available to weigh in on those.

Based on the Aug. 20 numbers, Chakko said the city did not believe a broken sewage pipe had caused the condition change in the Aquatic Park lagoon.

Andrea Pook, spokeswoman for the East Bay Municipal Utility District (EBMUD), said Thursday that the agency has had no breaks in its interceptor pipeline that runs along the east shore of the bay to the sewage treatment plant just off Interstate 80 in Oakland.

One question that remains is what might have caused the water level in the lagoon to rise in early August. Dye, the paddler, said a 10-inch rise would have required an influx of 50 acre-feet or 2.178 million cubic feet of water into the 60-acre lagoon.

He also noted that American Soil Products has a plant nearby that uses manure in its products.

“We typically don’t see any runoff from their site unless it’s raining,” he said, “unless it’s winter and there’s surface runoff.”

Bayer has been doing construction nearby, and Strawberry Creek runs through campus into the north end of the lagoon, Dye added.

Aquatic Park can be an oasis in the city. Photo: John Dye

Some community members have reported seeing dead birds and diminished animal life, but the city said its staffers check the park daily and have found no evidence of either. Water quality experts told Berkeleyside the bacteria levels shown in the Aug. 20 results would be unlikely to impact wildlife. Elevated temperatures in August might, however, have played a role if there have been impacts.

Several UC Berkeley professors said they suspect that leakage from sewer lines, or animal feces from the ground around the lagoon, could have contributed to the bacteria increase.

Jan O’Hara, senior environmental scientist with the SF Bay Regional Water Quality Control Board, said she suspects a water line broke and caused a surge of water, and a variety of bacteria, to enter the lagoon. With the tectonic nature of the area, she said, “it’s hard to keep the pipes from breaking.” She cautioned that this was just a hypothesis and that there could be some other source.

Speaking about the Aug. 20 results earlier this week, she said, “It’s not uncommon to see numbers like that and that happens when water levels rise. What matters is the context of what’s been happening.”

City spokesman Chakko said staff hypotheses about the water condition change earlier in the month revolved around widgeon grass that grows in the water and is a breeding ground for algae. The city cuts the grass monthly to try to limit its impacts.

Chakko also said the tide tubes that go between the San Francisco Bay and the park are likely a contributing factor, as well. Some of the tubes are blocked altogether, and others allow only a small amount of water to get through.

“They’re not working at optimal levels,” Chakko said this week. “They do need to be replaced.”

The city has allocated nearly $400,000 toward a planning process for that repair work as part of Measure T1.

UC Berkeley Professor Charlotte Smith, with the School of Public Health, said it clearly remains a mystery what may have caused the spike, though she suggested the possibility of leaky residential or commercial sewage pipes, or animal feces around the park, and noted the proximity of EBMUD’s sewage treatment plant in Oakland.

But even with the high E. coli levels, showing fecal contamination, she said, there’s no cause for panic.

“If there’s no body contact, there’s really no risk,” Smith said. “We only have risk where we have exposure. Just because something exists in the environment doesn’t mean we’re at risk.”

Emilie Raguso (former senior editor, news) joined Berkeleyside in 2012 and covered politics, public safety and development until her departure in 2022. In 2017, Emilie was named Journalist...