Working with the Queensland Government and Alluvium Consulting (Alluvium), NCEconomics staff helped to evaluate the cost effectiveness of investment options for meeting specific regional water quality targets across the Great Barrier Reef. Our work specifically focused on determining least cost pathways to meet these targets. Alluvium completed physical modelling to estimate reductions in pollution loads attributable to policy solution sets and from this we developed marginal and total abatement cost curves. A cost range was established for actions within each policy solution set and the total costs of achieving regional targets were determined.