The level of desperation from staff was laid out in a video and email sent on behalf of 93 union members to Dunedin City Council chief executive Sandy Graham in September.
In the email, which was released to the Otago Daily Times under the Local Government Official Information and Meetings Act, heritage collections senior library assistant Malcolm Deans said a lack of staff had left tired workers "anxious and demoralised".
"We have also been experiencing increasing abuse and threatening behaviour from members of the public, most noticeable over the last couple of years.
"Bare minimum staffing, especially in the evenings and on weekends, has left some staff feeling unsafe at work. This situation also has the potential to put public safety at risk."
Responding to what Ms Graham called a "powerful" video, a council senior manager held a meeting with staff in September and later started a review.
It is understood the review, which would look into ways to reduce pressure on staff and cover how the service might be better set up for the future, has led to further stress for some library staff.
Staff were told it was hoped the review would be done by Christmas, but a council spokesman said last week it was yet to be completed.
The spokesman acknowledged the process could be unsettling for staff, but reiterated it was not envisaged the review would lead to job cuts.
The union resorted to sending the email and video to Ms Graham after its earlier complaints were not acted on, it said.
In the email, Mr Deans told Ms Graham union delegates met council community services manager Simon Pickford and then library services manager Bernie Hawke in July to raise serious concerns over staffing levels and welfare.
The union requested more relievers to ease pressure on permanent staff, but had heard nothing back from Mr Pickford 11 weeks later.
Mr Deans said staff shortages had built up over the previous about eight years and been exacerbated by Covid.
"We have put up with budget-related hiring freezes and vacancies not being filled for excessive lengths of time.
"The worst example is one post being left vacant for well over two years and counting.
"Unfilled positions leave teams short-staffed, lacking leadership or even just the power to reach decisions, which are all stressful for those left to stretch themselves ever more thinly to cover widening gaps in services."
Staff had also been unable to take leave and there had been an impact on the quality of service provided to the public, with floor closures in the central library, as well as community library closures, Mr Deans said.
"We do not think this is an acceptable practice and we do not believe the Dunedin public are happy with this situation either.
"We have public service hard-wired into us, so being unable to provide those services, paid for by the community, leaves us anxious and demoralised."
In an email responding to concerns and inviting staff to take part in a Zoom meeting where they would be given an update on work to alleviate pressure on them, Mr Pickford acknowledged the situation had been difficult.
As well as the usual budget pressures across many council services, there was a significant amount of change across the library sector, he said.
Work was under way to redesign the central library space with some funding in the 2024-25 financial year.
"However, while we work toward this future state, we are very aware of the pressures on the library team which have been exacerbated by Covid and winter illness," he said.
"These pressures have been felt across the team and have sometimes affected our ability to deliver the service that is so highly valued by our community.
"These pressures have also impacted staff wellbeing."
