OAKLAND — Oakland’s embattled fire department, already under scrutiny for failing to inspect the Ghost Ship warehouse before this month’s deadly blaze, is facing a new round of allegations about its lax fire prevention efforts in one of the region’s most vulnerable areas to wildfires: the Oakland Hills, site of a 1991 firestorm that killed 25 people and destroyed thousands of homes.

Internal fire department emails obtained by this news organization conclude the department’s firefighters — tasked with regularly monitoring the hillsides — often signed off on properties despite overgrown vegetation around homes that clearly posed a high fire danger.

The issues date back to at least 2011 and persist to as recently as this month. One email, dated Dec. 15, shows department inspectors conducting spot checks earlier this year found fire hazards at 28 properties that had recently passed review by department firefighters. A 2014 email from a ranking inspector alleged that a property firefighters had passed turned out to be in “extreme violation” of safety rules.

“Any experienced firefighter with even basic knowledge of either structural or wildland firefighting could see these homes on this street are completely at risk and should have been marked out of compliance” and written up, the head of the department’s civilian wildland fire inspection team Vincent Crudele wrote to Deputy Fire Chief Mark Hoffmann.

Records show department infighting, arguments among people responsible for safety and what a city audit described as an attitude among firefighters that the inspections aren’t important.

The latest revelations upset Councilwoman Annie Campbell Washington, who represents neighborhoods at the center of the 1991 fire and said the city should investigate the integrity of the inspections.

“We suffered one of the worst wildfires in the country,” she said. “There’s no other part of the city that feels fire danger as severely. I take this extremely seriously.”

Both Fire Chief Teresa Deloach Reed and Fire Marshal Miguel Trujillo, who’s in charge of inspections, declined requests for interviews.

In an email sent on the chief’s behalf, she said: “Engine companies are directed to reinspect properties where deficiencies are identified. The Department makes every effort to ensure vegetation management inspections are done properly.”

The concerns about hills inspections raise new questions about whether the Oakland Fire Department can adequately perform an array of public safety inspections. The doomed Ghost Ship artists collective, where 36 people were killed Dec. 2, had never been inspected despite its owner registering it as city business 21 years ago. A fire station was right around the corner.

Last year, the department became the first in California to be stripped of its state certification to perform hazardous materials inspections of places like gas stations and industrial buildings where chemicals are used. In 2014, an Alameda County Grand Jury found more than a third of commercial buildings went unchecked despite city code that at the time had required annual inspections.

In the hills — where a firefighter and police officer were among the dozens killed in the 1991 blaze — firefighters are assigned to inspect about 21,000 residential properties each fire season. They are supposed to check for overgrowth of trees and bushes, tall weeds and grasses, dead vegetation, and even ivy growing on houses, which can act like a ladder for fire. A team of two full-time civilian inspectors, along with a few seasonal employees, check vacant lots and open lands. Those inspectors also investigate complaints about fire hazards, a duty that often leads to them spot-checking the firefighters’ work.

In 2013, then-City Auditor Courtney Ruby released an audit detailing problems with fire inspections in the hills dating back to at least 2011. “Our citizens’ lives are literally at stake,” Ruby wrote.

She identified the need for “stronger supervision, quality control measures, better oversight,” after finding lax enforcement and an attitude among firefighters that “fire inspections are not necessarily important.”

Current Auditor Brenda Roberts said Wednesday that many of the core problems remain with no firm timetable for fixing them. The department blew a deadline in February to explain how it would address the problems, and then missed a second deadline over the summer to formalize a vegetation inspection policy. Roberts plans to release another progress report in February 2017.

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In the wake of the Ghost Ship blaze, she indicated a broader look at fire inspections is planned. “Believe me that is high on my radar and has been,” she said. “Vegetation inspections are just one part of fire inspections.”

Many of the problems are highlighted in a 2014 email from the head of the department’s team of civilian vegetation inspectors to the deputy fire chief.

“Multiple homes on this street are in violation. Extreme violation to be frank,” Crudele wrote in a 2014 email to Hoffmann about properties on Pinehaven Road high in the hills above Montclair Village. Yet, Crudele said, a fire lieutenant had marked the properties as passing recent inspections in city records.

Crudele wrote that one property owner told him no firefighter had been by to inspect her property, which received a passing inspection but was “a mess.” Crudele wrote that he got nowhere when he later challenged the firefighter, Lt. Anthony Jackson, credited with the inspection in the city’s database.

“I stated that this level of inspection was substandard and unacceptable,” Crudele wrote. “His response was that he ‘doesn’t work for me’ and he ‘doesn’t want to do YOUR damn inspections in the first place.’ ”

Jackson did not respond to repeated requests for comment. Crudele, citing a department gag order, said he couldn’t discuss the email.

Hoffmann, in a telephone interview Wednesday, said he acted on the complaint, meeting with Jackson’s superiors and ordering new inspections of the area.

“They were forced to go back on it and told that any further complaints would lead to discipline,” Hoffmann said. He said he did not know the result of the re-inspections. The inspections are “extremely important,” he said, noting that he knows from experience: a house containing his belongings was lost in the 1991 firestorm.

Emails show Crudele kept up his complaints this year.

In June, he reported firefighters routinely failed to enter inspection results into the city database. Other inspections were not being completed because firefighters said they couldn’t locate the addresses or there was no access.

Still other inspections were incomplete or not accurate, the vegetation inspection manager wrote, but still signed off on by supervising firefighters.

“They are supposed to catch these errors and correct them, not just sign off in the upper left corner without reviewing their crews inspection quality,” he wrote.

On Dec. 15, Crudele alerted Trujillo and assistant Fire Marshal Cesar Avila that he and another vegetation inspector had turned up 28 properties with fire hazards that firefighters had marked compliant. He also reported that 47 inspections were missing from the system.

Sue Piper, a survivor of the 1991 fire and chair of the Wildfire Prevention Assessment District that collects special taxes from hills property owners to help fund the inspections, said the program is fraught with problems.

“For the people living in the hills, this is the number one public safety issue we have,” Piper said of the inspection process. She said she hears from people who report properties listed as passing that were clearly out of compliance.

The fire department released statistics recently claiming 99 percent of properties passed inspections this year.

But Piper was skeptical, saying members of her committee don’t trust the department’s numbers because detailed reports backing them up aren’t provided.

“The city doesn’t see they have a high liability,” she said, “and they are not taking it seriously.”