LAKE Macquarie faces environmental security risks worth $4.4billion by 2110, a city council report says.

The value of the risks, which related to natural disasters, climate change and pollution, stood at $249million last year, the report said.

The council said its sustainability department aimed to reduce those costs through managing contaminated land and air quality, flood mitigation and climate change adaptation.

‘‘The extent of risk reduction achieved through these programs is monitored and audited by council,’’ the report said.

The sustainability department has been criticised recently, with mayor Greg Piper and Cr Barry Johnston saying it should shed staff.

Their comments reflected wider concerns that the department was too big and too academic and must produce more tangible results.

Lake Macquarie councillor Phillipa Parsons defended the department, saying it did a good job.

Cr Parsons said surveys showed Lake Macquarie residents rated the environment a top priority.

‘‘The programs the sustainability department are implementing now are putting us in good stead,’’ Cr Parsons said.

Cr Johnston reaffirmed his concerns, saying the council had to ensure the department was ‘‘not wasting money or duplicating state issues’’.

Challenging criticism of the department, Cr Parsons said: ‘‘Council bashing is a regular occurrence in the media. It almost qualifies for an Olympic event.’’

Council general manager Brian Bell has not said publicly that the department, which he started, should shed staff.

But a council statement said the department had reduced staff by 12per cent in the past year.

The department had about 20 staff and a $9million budget in its first year in 2008-09, but now has 36 full-time equivalent staff and a $12.4million budget.

Councillors voted recently to significantly increase rates over seven years, which includes continuing sustainability programs.

On the weekend before the vote, the council advertised for a ‘‘sustainability engagement officer’’ earning up to $72,000 a year for a 35-hour week.

The council said the position was ‘‘required to meet commitments under the sustainability levy’’.