For decades Queensland’s sugar cane farmers have been throwing money into the creeks and rivers that flow past their properties. That’s the money spent on excess fertiliser that runs off during heavy rain and makes its way to the ocean. It’s estimated that three quarters of nitrogen fertiliser put on cane farms leaches from the soil within a few months of application.

When nitrogen and phosphorus fertiliser enters rivers and ends up in the Reef, it upsets the natural balance of the marine environment. Algae love nitrogen and phosphorus. In a high nutrient environment algae can then become so numerous that the sunlight that normally reaches the sea floor can no longer do so. That means seagrass and other light dependent bottom-dwelling organisms have trouble growing and reproducing. Crown of Thorns starfish that destroy hard corals also love nitrogen and that’s one of the reasons they are in such large numbers on the Reef at present.

The scientific community has recognised the need to reduce fertiliser and sediment runoff to the Great Barrier Reef for decades. Many plans have been made with the noble aim of reducing runoff but they have not resulted in much change. In 2003 the Reef Water Quality Protection Plan set a goal of reversing the decline in water quality to the reef within ten years. By 2009 another plan called for nitrogen loads to be halved by 2018, the result was a 17 per cent reduction.

A couple of years ago UNESCO considered putting the Great Barrier Reef on the “in danger” list because we were doing such a poor job of managing it. That would have been an embarrassment for Australians as well as threatening our tourism economy. Millions of people visit Australia from overseas each year and their main destination is the Great Barrier Reef. Without them Queensland’s economy would be in serious trouble.

In response, the Queensland Government has recently proposed new laws to ensure that the quality of water reaching the Reef is improved. The voluntary programs that have been in place for decades have been ineffective in reducing runoff. The new rules aren’t about punishing farmers, they are about ensuring farmers know how much fertiliser is optimal for their land and applying no more than is necessary. That is going to be good for the Reef and it's also likely to save a lot of money for sugar farmers.