Towards ecologically relevant targets for river pollutant loads to the Great Barrier Reef

► This study links river pollutant load reductions with GBR ecosystem outcomes. ► River TSS loads need to be reduced by 7,000ktons/yr (41%) to achieve GBR water quality guidelines. ► River DIN loads need to be reduced by 6,000tons/yr (38%) to achieve GBR water quality guidelines. ► If successful, current targets will accomplish 40% of TSS and 92% of DIN load reductions required. ► This highlights the need to establish ecologically relevant targets for river pollutant loads. Degradation of coastal ecosystems in the Great Barrier Reef (GBR), Australia, has been linked with a decline in water quality from land-based runoff. This paper examines the reduction in current end-of-catchment loads required for total suspended solids (TSS) and dissolved inorganic nitrogen (DIN) to achieve GBR water quality guidelines. Based on first-order estimates of sustainable pollutant loads, current TSS and DIN loads would need to be reduced by approximately 7000ktons/y (41%) and 6000tons/y (38%), respectively. Next, these estimated reductions for TSS and DIN are compared with Reef Plan targets for anthropogenic sediment (−20% by 2020) and nitrogen (−50% by 2013) loads. If successful, these targets will accomplish approximately 40% of TSS and 92% of DIN load reductions required to achieve sustainable loads to the GBR lagoon. These first-order estimates elucidate the need to establish ecologically relevant targets for river pollutant loads to the GBR for management and policy.