Nitrogen loading models are often designed and built without any input from decision makers. Better understanding and communication between modelers and decision makers would improve the usefulness of models. In interviews with sixteen modelers and outreach professionals in southern New England, USA, we inquired about how nitrogen-loading models should be designed and used in local decision-making. Qualitative analysis revealed several insights about: differences between models intended to advance science and those to advance policymaking; matching the scale of the model with that of the decision; the danger that models might promote technocracy; how to present uncertainty information; ecological transferability and social acceptance of models to new locales; involvement of local decision makers and citizens in the design of models; and the use of models by lay decision makers. The findings highlight both opportunities and obstacles to the use of models in local policy making.