Biosecurity incursion response decisions require timely, high quality information involving science and economics. The value of the impact on indigenous biodiversity is a key aspect of the economics typically involving cost-benefit analysis. The hypothetical incursion of Biosecurity New Zealand’s top priority weed hydrilla (Hydrilla verticillata) in a typical New Zealand lake (Lake Rotoroa otherwise known as Hamilton Lake) elicits dollar values of impacts on indigenous biodiversity in a freshwater environment. Using the stated preference tool, Choice Modelling, the experimental design was maximised for efficiency of Willingness to Pay (WTP) estimation. The survey method of community meetings of four population samples at varying distances to the incursion site is a cross between a mail survey and an individual interview survey. Results show an efficient design with minimal sample size and biodiversity attributes that have values statistically different from zero but not statistically different between locations.