Staff costs at nine Perth councils jumped more than 5 per cent last year, paving the way for ratepayer-funded local government salaries to push past $1 billion for the first time.

In rapidly growing southern council Rockingham, staff costs jumped 10.9 per cent or more than $5 million.

The next highest rises came mostly from smaller inner city councils: Belmont and Mosman Park tied at 8.8 per cent, then East Fremantle (8 per cent), Victoria Park and South Perth (both 7.4 per cent) and Vincent (6.5 per cent). Mandurah (6 per cent) and Kwinana (5.7 per cent) were the other big risers.

Those increases were offset by nine councils — including many of Perth’s biggest — that slashed employee costs in 2017-18, limiting the overall rise to just $8.5 million or 0.8 per cent.

Still, that pushed the total figure into 10 figures for the first time at $1.075 billion.

In Subiaco, staff costs fell 12.1 per cent, while Kalamunda (down 7.3 per cent), Wanneroo (5.8 per cent), Canning (5.2 per cent), Stirling (3.6 per cent) and Joondalup (2.4 per cent), Nedlands (2.3 per cent), Perth (2 per cent) and Fremantle (0.9 per cent) also found savings worth a combined $18 million.

City of Rockingham chief executive Michael Parker attributed the steep payroll rises to the City assuming management of the Warnbro Aqua Jetty and Mike Barnett Sports Complex.

A three-year project to overhaul IT systems — with a view to long-term savings — was partly behind South Perth’s jump, chief executive Geoff Glass said. In Belmont, some retiring senior employees received higher-than-normal termination payouts.

Mosman Park executive manager corporate services Bronwyn Rose said the affluent locality had expanded its ranger coverage to seven days a week and paid out a number of redundancies.

“Environmental health services were brought in-house as they were too expensive when outsourced,” she said.

Victoria Park froze recruitment during 2016-17 as part of a review of staffing levels before filling vacant positions last year, leading to the jump.

Other councils blamed their rises on annual leave accrual, expansion of services, increased insurance costs and annual salary bumps.

City of Wanneroo Mayor Tracy Roberts said her council had slashed staff costs despite adding about 8000 residents last year. “The reduction in staff costs is a reflection of the City’s strong focus on implementing organisational services efficiencies and minimising cost pressures faced by our community,” she said.

In Canning, a detailed review of staff structure undertaken by incoming chief executive Arthur Kyron in 2016 is continuing to pay dividends for ratepayers. Subiaco reduced costs after ceding a large part of it municipality to the City of Perth in 2017.

Joondalup chief executive Garry Hunt said the digitisation of administration and business operations had helped reduce costs, while acting Nedlands chief executive Martyn Glover said trainees and apprentices had been introduced in some roles.