The Great Barrier Reef — the world’s largest living structure — is in trouble. Recent surveys have shown that over 90 percent of the 1,400 mile structure has been affected by some level of coral bleaching — an event that occurs when corals, stressed by rising water temperature and acidity, expel the symbiotic algae living within their tissues. This bleaching event, which is the worst in the reef’s history, has killed 35 percent of its corals in the northern and central regions.

While climate change-triggered ocean acidification and warming are the main culprits, the damage has been further exacerbated by sediments flowing onto the Great Barrier Reef as well as by fertilizer and pesticide runoff from farming.

In order to give the bleached corals in the region a better chance of recovering, activists have long demanded, among other things, immediate implementation of steps to improve the water quality in the removing land-based pollutants.

A new report commissioned by the Queensland government has now provided an estimate of what this is likely to cost over the next decade — 8.2 billion Australian dollars ($6.3 billion).

The money would be needed to reduce sediment runoff into the Great Barrier Reef by up to 50 percent below 2009 levels by 2025, and to cut nitrogen levels by up to 80 percent — targets that are part of the federal government’s Reef 2050 Plan.

“The cost estimate of the current policy solution sets to meet the regional Reef 2050 Plan targets for the GBR requires a significant increase in investment from current levels,” the report said. “Failure to increase current levels of investment could result in costs that are higher than the most likely estimate. Efficient policies should result in costs closer to, or potentially lower than, the most likely estimate.”

The lion’s share of the expenditure would be incurred in reducing the sediment runoff from the Fitzroy catchment — one of the reef’s five catchment areas. According to the report, halving sediment runoff from the farm-heavy catchment by 2025 would cost nearly 6.5 billion Australian dollars ($5 billion).

“The recommendations set the stage for a bold new era of reform in water quality improvement and that is what we will deliver,” Queensland Environment Minister Steven Miles said in a statement released Thursday. “We have agreed, or agreed in principle, to also review the reef water quality targets, better communicate how everyone can improve reef water quality, use incentives to drive water quality improvements, pursue targeted regulatory approaches, develop a strategic investment plan, and simplify and strengthen governance arrangements.”