Earlier in the month, councillors approved a two-lot subdivision at 538 Ophir Road, however council staff noted in the report further subdivision and associated population growth could put the area into the next risk level, requiring the council to complete further upgrades to the dam itself. 

The council has already spent $19 million on upgrades, including raising the dam wall by a metre.

Councillors resolved on Tuesday to put a planning proposal together in consultation with landholders to increase the minimum lot size.

The report to councillors noted the recently-completed upgrades to the dam were based on the existing infrastructure and population downstream of the dam to meet the negligible life safety risk threshold should the dam fail in an extreme event.

“Should the population downstream of the dam increase further by way of additional development, the ‘negligible risk’ threshold may no longer be met,” the report said.

“As this locality is not considered to be a suitable to provide for population growth controls to restrict further development are therefore recommended.”

The report said 19 lots in the inundation area along Ophir Road, Bulgas Roas and Summer Hill Creek could potentially be subdivided in future years, also including in properties in Coolabah Drive, Trooper Place and Old Regret Road.

The potential yield would be 71 lots, although 31 was a more likely total.

Dam consultant Entura found 31 lots would pose additional risk over time, but it would fall close to the NSW Dam Safety Committee’s negligible risk cutoff and the risk could be minimised through emergency planning and extending the current flood warning system to cover all future developments.

At Tuesday’s meeting, councillor Neil Jones asked whether the the process could carry implications for residents’ insurance.

Technical services director Chris Devitt told councillors he did not believe so, but the council wanted to avoid the loss of life risk.