The head of the Oakland police union sent a scathing letter Monday to the president of the City Council citing a police staffing crisis and calling on her to “stop the anti-police rhetoric” — to which the City Council president fired back to say she and others value the Police Department’s work.

In a letter addressed to City Council President Nikki Fortunato Bas, Barry Donelan, the head of the police union, said the staffing crisis is “fueled by the anti-police rhetoric continually streaming from your City Council meetings, which is driving hardworking, dedicated Oakland police officers to leave in droves at a time when Oakland residents are facing decade-high levels of violent crime.”

In his letter, Donelan said that from 2010 to 2020, the city lost an average of 60 officers per year, mostly due to retirement. In 2021, the Oakland Police Department lost 86 officers — 37 transferred to different law enforcement agencies, 22 left law enforcement and 27 retired.

The letter was sent to the entire council, Mayor Libby Schaaf and Police Chief LeRonne Armstrong.

Bas responded with her own letter to Donelan on Monday night and said she and other council members have publicly stated they value the department’s work.

“For you to suggest otherwise using divisive, inflammatory rhetoric is dangerous and simply untrue,” Bas wrote. “All of us are working hard to reduce violent crime and achieve safer streets and neighborhoods — and for those solutions to be effective, we all need to unite as a City and work together.”

Oakland has been grappling with a police staffing crisis over the past year — reflecting a nationwide trend of officers leaving police departments in droves. Schaaf has urged the council to approve funding to hire more officers to help with the rise in violent crime seen in 2021. The City Council approves the city budget and the Police Department recruits officers. In early December, Schaaf said the police staffing levels “are at a crisis right now.” The council voted in December to add more police academies to boost the department’s staffing.

Oakland police have said in previous council meetings that department personnel have left for a number of reasons, including dissatisfaction with department leadership, workload and feeling a lack of support.

In her letter to Donelan, Bas wrote that she has called for adding more “community-based neighborhood policing approaches to reduce violent crime at the neighborhood level, with a focus on the neighborhoods most impacted by gun violence, human trafficking, and violent crime.”

Bas also noted that she has advocated for more resources to address the root causes of crime, including investments in homelessness solutions, mental health help and generating jobs.

“I will not allow my full-throated advocacy of a holistic, well-rounded approach to fighting crime to be distorted by you or anyone else,” Bas wrote.

In his letter, Donelan called on the city to “support your Oakland police officers” and engage with the department to stop people from leaving. He said he invited all the council members in 2020 to “thank your police officers,” but only one only council member, Treva Reid, took him up on the offer.

“The fact you and your colleagues are unwilling even to say thank you to the men and women who strive everyday to protect the residents of Oakland speaks volumes and is at the core of what is driving this exodus of police officers out of Oakland,” Donelan wrote.

He also called on the city to move mental health calls to the Fire Department’s Mobile Assistance Community Responders of Oakland, known as MACRO. Donelan said moving mental health calls out of the Police Department will help the department’s workload. Last year, the city hired a program manager for MACRO and is currently in the process of hiring technicians.

MACRO is not yet off the ground, but is expected to launch early this year.

Bas called on Donelan to work with the council to address public safety.

“The stakes are too high to put politics over the community’s safety,” she wrote. “I, for one, am ready, willing and able to do that.”

Last year, the department’s staffing reached below the minimum 678 officers required by Measure Z, a 2014 voter-approved parcel tax that funds public safety and violence intervention programs.

Now the department’s ranks have dropped to 673. The city budget currently has funding for 737 sworn positions, but the department struggled to fill the vacant positions.

The City Council has passed a number of measures to address the staffing issues. In December, the council approved two more police academies, bringing the total to seven academies over two years, to help boost the department’s ranks and directed city staff to hire a professional recruiter to help lure experienced police officers.

At the December meeting, Armstrong said existing officers need more support because they face bigger workloads as employees retire or transfer departments at a higher rate than expected.

The mayor and Police Department had applauded the council’s move to add two police academies. Council Member Sheng Thao, who introduced the proposal, said at the time, “As a council member and a mom, I have heard the anger and the fear.”

However, Donelan told The Chronicle on Monday that the addition of new academies hasn’t kept up with the number of officers leaving the department.

“I am absolutely supportive of the academies,” Donelan said. “Even with as many academies as they’ve pushed through, they can’t keep up with the attrition.”

Thao, who is running for mayor, also introduced a proposal to offer $50,000 cash bonuses to attract officers to the department. But that proposal has not yet been voted on.

Council Member Loren Taylor has also advocated for more police resources and had wanted to front-load the number of academies in the first year of the city budget to help with the loss in staff, but his proposal was rejected.

Donelan said the department has lost 18 officers since the start of the year, including 13 who left in February.

Sarah Ravani is a San Francisco Chronicle staff writer. Email: sravani@sfchronicle.com Twitter: @SarRavani