The North Berkeley landmark has been on the receiving end of soap and colored dye multiple times in the past year, and it is no easy feat to clean up the messes.

The bears of the Marin Circle fountain are taking a bubble bath.

On the receiving end of a bottle of detergent earlier this week, the North Berkeley landmark is now a pool of suds awaiting a costly clean-up. It is the second instance of vandalism of the fountain in just the past two weeks.

“For some reason, there’s been a rash of these in the past year,” said Michael Gray, a neighbor and the president of the board of directors of the Friends of the Fountain and Walk, a non-profit volunteer group. The organization has tracked four instances of tampering in the past several months, he said, including an “epic soaping” in December.

Berkeley spokesman Matthai Chakko said the five or six incidents of fountain pollution the city responds to yearly are usually clustered around high school and college graduation time.

“People might think it’s fun or cute, but this is vandalism,” he said. It costs the city around $1,000 to clean and refill the fountain each time, he said.

And it is no easy feat to remove soap — or colored dye, which was added over Memorial Day weekend — from the fountain. The structure is connected to the storm drain system instead of the sewer system, preventing the tainted water from simply being drained, as it would pollute the bay. Instead, volunteers do their part to scoop out the foam early on, until the city comes in with a big vactor truck to suck it all up and refill the fountain with clean water.

“Whatever we do takes days and days and days,” Gray said.

The Friends organization was established in 1993 to bring the now century-old fountain back to life. The original was built in 1911 and destroyed in 1957, when a truck barreled into it. The Friends celebrated the 20th anniversary of the current concrete fountain last year. Now the group helps handle maintenance, beautification — and disaster control.

“We’re trained in how to clean filters, replace filters and make sure things are working right,” Gray said. “We rely on the city for the bigger-ticket stuff like bringing out the machine and refilling it. They have been great about responding.”

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In May, the neighbors, at the end of their ropes, reported an act of vandalism to the police for the first time. They are also thinking up possible preventive measures, like installing a sign that says vandalism is prohibited.

Councilwoman Sophie Hahn, whose district includes the Marin Circle, plans to meet with the neighbors to discuss possible preemptive acts that can be taken to avoid resorting to “criminalizing” those who pollute the fountain.

“Our goal is to have the community better understand that what seems like it might be a fun and innocous and harmless prank actually can damage the fountain, and it’s a very costly thing,” she said.

In the meantime, the fountain should be up and running again on Thursday, Chakko said.