The rumbling of city trucks packed with shovels, leaf blowers and telescoping pole saws broke through the stillness of a recent cool, gray morning in San Francisco’s Outer Mission neighborhood.

Sidling up to a line of trees next to the Pacific Supermarket on Alemany Boulevard, a crew of professional pruners from the Public Works department set to work hoisting themselves into the tree-tops to trim off gangly, drooping limbs and feed them into a wood chipper.

It seemed like an ordinary scene, but the crew was in the midst of an unprecedented change in San Francisco.

Starting Saturday, the city will for the first time take full responsibility for the care and maintenance of the nearly 124,800 street trees in the city’s right of way, sweeping aside its unpopular practice of making property owners care for most of the trees.

In November voters passed Proposition E, which set aside $19 million annually from the city’s general fund for Public Works to maintain the trees and the sidewalks surrounding them — most everything short of raking leaves and fallen twigs. Both property owners and people who want to see San Francisco’s civic forest remain healthy have welcomed the change.

The city had long maintained a clunky and often confusing system of designating tree-care duties, sometimes making it difficult to know who was responsible for a particular tree. It was assumed that property owners would care for trees they planted, with the city taking charge of trees on major thoroughfares.

“The policy we used to have actually made no sense from so many different directions,” said Dan Flanagan, executive director of the nonprofit Friends of the Urban Forest, which campaigned for Prop. E.

“A lot of people didn’t know they were responsible for the trees to begin with; and if they did, they couldn’t afford it,” he said. “That’s why we got 79 percent of the vote.”

Confusion over who was responsible for a decades-old cypress in Noe Valley contributed to its unpermitted removal last month. Though the tree appeared to be on private property, nestled next to an apartment building, the city actually owned it.

“Neighbors were absolutely devastated to see it gone one day,” said Carla Short, superintendent of the city’s Bureau of Urban Forestry. The property manager that had the tree chopped down, Greentree Property Management, will be fined $8,000 and says it will pay.

“There was some confusion regarding the ownership of the tree based on its location, but the removal of the tree was not intentional,” Greentree spokesman Ron Heckmann said, adding that the company had “initiated a donation” to the Friends of the Urban Forest “to create significant tree plantings and landscaping in the Clipper Street area.”

When tree maintenance budgets were slashed in 2011 amid broader spending reductions, the city made the deeply unpopular decision to shift care of thousands of trees to private citizens.

Prior to Prop. E. taking effect Saturday, property owners were responsible for more than two-thirds of all city-owned trees, Short said. Under the city’s old rules, property owners could face fines if their pruning harmed those trees or they otherwise failed to live up to city codes.

Back to Gallery San Francisco takes back its trees, to the relief of... 4 1 of 4 Photo: Paul Chinn, The Chronicle 2 of 4 Photo: Paul Chinn / The Chronicle 2017 3 of 4 Photo: Paul Chinn, The Chronicle 4 of 4 Photo: Paul Chinn, The Chronicle







“Suddenly, you’re given this role. You’re not a tree expert, you have to pay to have someone take care of it and you’re still getting a bill of $2,500 from the city for not doing it right — that was a major frustration,” said Charley Goss, manager of government affairs for the San Francisco Apartment Association, an advocacy group for landlords.

An even bigger concern, Goss said, was the liability property owners could face from sidewalks swollen and cracked by tree roots.

“Maybe the way a sidewalk is damaged creates a tripping hazard,” he said, “and if someone gets hurt, who are they going to look to?”

Data compiled in a recently completed census of the city’s trees have helped Short and her team map out block by block which trees need the most attention. Over the first two years of Prop. E’s implementation, crews will prioritize trees that are in decline or pose potential safety hazards, gradually moving on to those with less pressing needs.

Under Prop. E, the city will assume responsibility for sidewalks damaged by trees, but residents who previously received notices from the city to prune a tree or fix a cracked sidewalk may still be held liable until that repair work is completed, said Public Works Director Mohammed Nuru.

“We’re not going to go after you, but you’re taking a risk because if someone trips and falls, or the city has a lawsuit, we’re going to be holding hands with you in court, saying, ‘You knew to do this repair, and you didn’t do it,’” Nuru said. “It doesn’t mean we’re not going to do (the repair work), but if something happens, you’re taking a risk.”

Work will begin soon, but Short said that San Francisco residents shouldn’t expect to see caravans of tree-trimming bucket trucks descending upon the city’s streets right away.

“We’re going to be systematic about this, and we can’t necessarily respond to individual requests, so we’re asking for patience as we get the program up and going,” she said.

“Our hope is that within three to five years we will have brought all the trees to a baseline standard, and then we’ll be on a routine pruning cycle based on the species and needs of any particular block,” Short said.

Using data from Public Works’ tree census, the city will then establish a maintenance schedule for each tree. Short said that schedule will be posted online soon.

Short is also looking to bolster the size of the fleet of specialized tree-trimming trucks and double the number of people on her in-house pruning crew. About 75 percent of city tree trimming is now done by contractors; Short hopes to eventually get that down to 50 percent.

Transferring tree maintenance responsibilities back to the city, she said, will also be a boon for the trees themselves. Research conducted on behalf of Public Works found that overall, “city-maintained trees tended to be larger and healthier than privately maintained trees, and that was consistent with research from other cities,” Short said.

“If we’re successful in getting the word out, my hope is that people say, ‘Great, that tree is your responsibility now, I’m not going to touch it.’ People were trying to do the right thing, but they didn’t do the research or didn’t understand how. Now they’ll say, ‘I’ll let the city do it,’” she said.

Dominic Fracassa is a San Francisco Chronicle staff writer. Email: dfracassa@sfchronicle.com Twitter: @dominicfracassa