Lake Macquarie council’s sea level rise policy said it was ‘‘appropriate to prepare for a linear increase of 1centimetre [10millimetres] in sea level a year’’ from 2008 to 2100.

Data shows that sea levels have risen by only 2.6millimetres a year from 1991 to 2011.

A council statement said the bureau’s National Tidal Centre provided data on sea level rise from 14 gauges around Australia, which were ‘‘corrected for changes in land elevation and barometric effects’’.

‘‘The closest gauge to Lake Macquarie is at Port Kembla, which has recorded a 2.6-millimetre-a-year increase [since 1991],’’ the council said.

The council said mean lake level had risen sevencentimetres over the past 25 years, which equated to 2.8millimetres a year.

The council said the state government monitored lake levels, but they were ‘‘not a measure of sea level rise, as flows between the sea and the lake are restricted by Swansea Channel’’.

The NSW Department of Planning said in its assessment of a Lake Macquarie Yacht Club redevelopment plan that there was ‘‘uncertainty surrounding the manner in which sea level will rise’’. The council said it agreed with that analysis.

‘‘There is uncertainty around the timing of predicted future sea level rise,’’ the council said. ‘‘It may occur slower or faster than the NSW Sea Level Rise Policy benchmarks.’’

The state policy planned for sea levels to rise 40centimetres by 2050 and 90centimetres by 2100, from ‘‘mean sea level’’ in 1990.

The policy said that was based on ‘‘the best national and international projections of sea level rise along the NSW coast’’.

The Newcastle Herald has recently reported Belmont developer Jeff McCloy is planning a class action against Lake Macquarie councillors for devaluing and restricting waterfront properties with its sea level rise policy.