When a foul-smelling slop began bubbling out of a manhole in Tiburon the other day, the leafy streets of Marin County became an unlikely spot for what may be the latest fallout from the coronavirus: sewage spills.

The shortage of toilet paper that’s come with the pandemic-induced shopping panic has prompted many people to get creative on the commode. They’re flushing the likes of disposable wipes and paper towels into sewer lines, wastewater officials say, and creating blockages that are leading to messy system overflows.

“I’m sure it’s happening all across the state,” said Tony Rubio, district manager of Sanitary District 5 of Marin, where crews rushed to Mar East Street along San Francisco Bay in Tiburon on Sunday to clean up 100 gallons of wastewater on the road. “It’s not a maintenance problem we normally have to deal with.”

A day later, though, his crews were back at it, unclogging a sewer pumping station on nearby Paradise Drive. Also on Monday, neighboring Las Gallinas Valley Sanitary District in San Rafael was trying to contain 550 gallons of wastewater pouring onto Professional Center Parkway east of Highway 101. The culprit in each of these cases, the districts say, was a system blockage caused by something that shouldn’t have been there.

“People are really nervous about this virus and they’re flushing anything they can use down the toilet,” said Mike Prinz, general manager of the Las Gallinas district. “If people are using non-flushables, there’s a good probability that they’re going to contribute to a spill not far away from their home.”

Filings with the State Water Resources Control Board show that 30 agencies have reported a total of 39 sewage spills since the beginning of March. The number of spills is probably higher, though, because sanitation agencies have as long as 60 days to disclose the incidents.

Officials at the State Water Board said it was too early to know for sure whether the coronavirus was driving an uptick in sewer problems, but the agency issued an uncommon public notice this week advising people to flush only toilet paper down the can.

The fear is that both the scarcity of toilet paper and calls by health experts to use disinfecting towels and wipes to keep surfaces clean may lead to more non-biodegradable products getting into sewer systems.

Sewer blockages and overflows not only are unsavory, but they also can send harmful pollutants into neighborhoods and creeks, including the coronavirus itself.

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The Centers for Disease Control and Prevention confirms that the virus has been detected in the fecal matter of people diagnosed with the corresponding illness COVID-19. The agency does not yet know what the risk of infection is.

Steve Moore, head of the Ross Valley Sanitary District in Marin County, said he is not taking any chances with his staff. He has directed district workers to stop pressure-washing sewer lines to make sure the virus isn’t transmitted through the spray of wastewater.

The Ross Valley district, which serves Larkspur, Fairfax, San Anselmo, Kentfield and Ross, hasn’t experienced any recent spills. But Moore said it may be just a matter of time. The 19 screens and buffers that keep problematic material out of his district’s 200 miles of sewer lines, which workers periodically clean out, have been amassing more debris than usual lately. Moore says they’re doing all they can to keep up with the cleaning.

“We’re worried that we’re going to get some (backups). That’s why we’re trying to get the word out,” he said.

The increased use and sales of disposable wipes, which have been scant on supermarket shelves lately, is understandable given the advice of health experts, who urge cleaning doorknobs, desks, kitchen tables and countertops to kill the coronavirus. Booming sales of toilet paper are less explicable, however, something psychologists say is purely reactionary.

This week, even Gov. Gavin Newsom’s family was having trouble finding TP. His wife, Jennifer Siebel Newsom, tweeted Wednesday, “And yes, unfortunately the thorn — we run out of toilet paper, paper towels and Kleenex tomorrow. I wish people had not hoarded.”

Using alternatives to toilet paper and flushing them into sewer systems is not a new problem. Sanitation districts have long been trying to educate their customers about how even products marketed as “flushable” don’t degrade easily and urging them never to substitute paper towels for toilet paper.

“Think about every paper towel commercial you’ve ever seen telling you how strong the paper towels are,” said Chris Carpenter, community affairs representative for the Central Contra Costa Sanitary District. “I tell people the three p’s: pee, poop and (toilet) paper. That’s the only thing we want down the drain.”

A bill before the state Legislature, authored by Assemblyman Richard Bloom, D-Santa Monica, would require “nonwoven disposable products” like wipes to be clearly labeled as unsuitable for flushing.

Graham Jones, owner of Genteel Plumbers in San Francisco, has another idea — a fix that won’t lead to errant objects in the toilet or require people to seek out hard-to-find toilet paper: buy a bidet.

“You just wash off your buttocks with the sprayer,” he said. “It’s really nice. I have two at my house and one at my shop.”

Jones said he is offering big discounts on hand bidets and installation, at least until the coronavirus goes away.

Kurtis Alexander is a San Francisco Chronicle staff writer. Email: kalexander@sfchronicle.com Twitter: @kurtisalexander