WaterNSW claims Warragamba dam wall project stacks up despite not knowing cost of offsets

The NSW government proposes to raise the wall of the Warragamba dam by 14 metres. Photograph: Carly Earl/The Guardian

The New South Wales government agency charged with delivering the controversial raising of the Warragamba dam wall insists the project will have an overall economic benefit, despite not knowing how much it will have to pay in environmental offsets.

Dismissing criticisms of the project, WaterNSW on Monday released a series of long-awaited reports responding to almost 2,500 submissions objecting to the plan to raise the wall by 14m in a controversial bid to reduce flood risk in the Hawkesbury-Nepean Valley.