The Turnbull government will establish a special $1 billion fund to protect the Great Barrier Reef from the ravages of climate change and declining water quality.

The Reef Fund – to be announced by Prime Minister Malcolm Turnbull in Queensland on Monday – will invest in clean energy projects across the reef's catchment area in a bid to keep the World Heritage-listed icon healthy.

Under the first major environmental policy announced by Mr Turnbull during the campaign, the money will be come from the Clean Energy Finance Corporation's $10 billion special account – meaning it will not affect the budget bottom line.