Murky waters

Report of swimmer’s infection raises concerns of hygiene, cleaning schedule at Sycamore Pool

While city officials say swimming at Sycamore Pool is currently safe, they acknowledge that drought conditions are encouraging the growth of potentially harmful bacteria.

While city officials say swimming at Sycamore Pool is currently safe, they acknowledge that drought conditions are encouraging the growth of potentially harmful bacteria.


Though its beauty is without question, some would say that actually swimming in Sycamore Pool is another matter entirely.

That’s the sentiment of a local blogger whose recent posts about a family member—who reportedly contracted skin and eye infections after swimming at One-Mile Recreation Area—made the rounds on social media, raising doubts about the cleanliness of Chico’s iconic concrete swimming hole. The stink has also shed light on what many swimmers might not know: For years, Sycamore Pool was cleaned every week on Thursday, but it’s been on a much less regular schedule since July 2011.

The change wasn’t clearly communicated to the public. Its only mention is on a city staff report presented to the Bidwell Park and Playground Commission in July 2011 that doesn’t specifically name Sycamore Pool. It explains that staffing levels had limited the Park Division’s ability to clean the pool on a weekly basis, and that “a full cleaning will occur every two weeks.”

Dan Efseaff, manager of the Park Division, told the CN&R it’s no secret that the pool has been drained and cleaned only once every two or three weeks, depending on need and available staff. Many Bidwell Park users have surely observed that by walking over the dam on Thursday mornings, he said. Further, his department hasn’t received any complaints about the cleaning schedule of Sycamore Pool—not until the recent report of an allegedly infected swimmer.

The results of testing conducted by the city at Sycamore Pool suggest the water is safe for swimming, but Efseaff acknowledges that the current conditions in Big Chico Creek—low water flow and high temperatures—are ripe for bacterial growth, and predicts the city will close the pool earlier than usual this summer as a result.

On Thursday mornings when the cleaning does take place, a grate on the shallow end diverts water from Big Chico Creek underneath Sycamore Pool while a crew of four to six city workers uses a street sweeper and pressure-washers to remove algae from slippery surfaces and make small repairs when necessary.

The city removes algae from the pool mostly to minimize the risk of slipping and to keep the water clear so lifeguards can observe swimmers underwater—not necessarily for hygienic purposes—which is why Efseaff says “‘cleaning’ is kind of a misnomer.”

For instance, whereas cleaning most public pools would involve treating the water with chemicals, Sycamore Pool can only be as clean as the rest of the creek.

“The micro-organisms that were in the creek yesterday will likely be there tomorrow, too,” Efseaff said.

After cleaning, how long it takes for the pool to fill back up depends on the time of year. Under normal summer conditions, it’s only a matter of hours. But now, in the midst of California’s ongoing drought and with Big Chico Creek running low even for July—it’s reportedly been disappearing underground on Chico State’s campus, Efseaff said—filling back up takes more than 24 hours.

That’s part of the problem. The low level of the creek ensures that water moves slowly through Sycamore Pool, which is conducive to bacterial growth, said Gabriel Kopp, director of operations at local environmental consulting firm FISHBIO.

“If you go to Lake Tahoe, it’s frigid when you get in and the water is super clear,” he explained during a phone interview. “Then you go out to some backwater off the Sacramento River, a pond that’s all mossy and green because it’s warm. The longer water sits and starts to warm, the better the conditions for the formation of bacteria.”

And greater presence of bacteria such as E. coli, found in human fecal matter, increases the risk of human infection and illness, Kopp said. The city does conduct weekly testing of the water at Sycamore Pool, measuring both total coliform—a broad category of bacteria that aren’t necessarily harmful, but may indicate the presence of pathogenic organisms—and fecal coliform, a specific measure of human waste. (To view the results, go to

Efseaff pointed to Butte County Public Health policy recommending that water used for recreation not exceed 500 fecal coliform organisms per 100 milliliters. A reading over that threshold calls for a resample and survey for possible sources of contamination, while a sample over 5,000 per 100 milliliters calls for immediate closure of the swimming area.

However, the county actually has updated its policy to comply with federal recommendations that are more stringent. The U.S. Environmental Protection Agency advises that “no more than 10 percent of total samples during any 30-day period exceed 400 per 100 milliliters.”

“The rate of eight cases of illness per 1,000 swimmers is estimated to result from exposures to waters containing … the fecal coliform indicator group at the maximum geometric mean of 200 per 100 milliliters,” the recommendation reads.

On June 30, the date of the most recent sample posted on the city’s website, the water contained 350 fecal coliform organisms per 100 milliliters. And twice, on April 23 and May 9, readings were as high as 540 per 100 milliliters.

While Kopp says that those results are concerning, he warned against drawing dramatic conclusions from a small collection of data. More testing is necessary to “see if there is a steady trend, to see if four or five samples come back really high,” he said. “I imagine that would be their first response.”

The Park Division did collect an additional sample after being informed of the infected swimmer, Efseaff said. The results were the same as the last reading on June 30—350 fecal coliform organisms per 100 milliliters, well under the threshold recommended by Butte County Public Health.

Even so, Efseaff envisions that conditions at Sycamore Pool will only get worse as the summer and the drought deepen.

“With the creek as low as it is, it’s likely we’ll close the pool in a few weeks because we can’t keep up with the algae build-up, the water won’t have much opportunity to move through and the quality of the water coming in might not be that good.”