Military testing ranges 30km offshore from Wollongong could block any chance of a proposed offshore wind farm being moved further away from the coast.
And it has residents asking why bombing and practice ranges are needed so close to cities.
BlueFloat Energy proposes to build an offshore wind farm with 105 turbines at least 200m high, starting about 14km off the coast between Wollongong and Shellharbour.
The impact on the view out to sea has been drawing concern from residents - even those in favour of renewable energy.
But the possibility of moving the turbines further out would butt up against declared military exclusion zones which start about 30km offshore, where navigators are warned not to enter.
Maps from the Australian Hydrographic Office show a web of these ranges with varying purposes.
Related documents state the two directly off Wollongong, named R485A and R485B, are for naval flight training.
Others further out and moving south, including R495A which spreads east and south from off Bass Point, are listed as being for "firing, bombing, radar tracking", under control of the navy.
A Defence spokesperson confirmed the maps were current but did not say whether the ranges had recently been used.
"Military firing practice areas are promulgated to meet Defence training requirements," the spokesperson said.
"The activation of training areas to meet training requirements occurs on a frequent ongoing basis with dynamic training schedules subject to late changes.
"Although the activation of training areas is publicly notified, the details of the training activities conducted are not publicly available for operational security reasons."
Dapto resident Colin La Flamme first found out about the ranges at a community information session held by BlueFloat last week in Thirroul.
He said the wind farm may gain more public support if it was less visible further out to sea.
"I don't see why we need a military firing zone 30km out to sea," he said.
"I don't think anyone knew that was there.
"I'd be interested for the Federal Government to review that so that they'd get a bit more local support from people [for the wind farm] if it was a bit further out and a little bit less visual impact."
He had several questions about the range.
"What do they use it for, to blow up things with submarines?
"Do they use it, and if they don't use it why is it there, and why is it needed? And why is it more important than the local community?
"I don't think it is. Could it be somewhere else maybe?"
BlueFloat Energy country manager Nick Sankey declined to comment on the military ranges other than to say his company's proposed site had respected these areas.
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