A Labor government would implement a $200 million environmental plan designed to protect the Great Barrier Reef from climate change and declining water quality.

Opposition Leader Kevin Rudd unveiled the policy while visiting the reef today, describing it as the largest-ever single financial contribution to help secure the future of the reef, one of Australia's best-known tourist attractions.

The bulk of the funding package is $146 million for a new water quality grants scheme.

Mr Rudd said the climate change initiative would benefit the reef, local landholders and farmers, and the tourism and fishing industries dependent on the reef.

The money will come from the Natural Heritage Trust in the form of grants to landowners who reduce run-off and sediment loss into the sea and the reef.

"The Great Barrier Reef is Australia's greatest natural asset and we have a responsibility to the next generation of Australians to do whatever we can to properly preserve it," Mr Rudd said.

He said climate change was already having an impact on the reef which was also under threat from sediment and nutrient run-off from farming activity in the area, predominantly sugar cane.

"This also is of a critical nature when it comes to the quality of water in the areas surrounding the reef itself and it affects, therefore, the long term of reef eco-systems."

Mr Rudd said he was confident the two could co-exist by encouraging farmers to improve land-management practices.

AAP