For infectious diseases like tuberculosis and HIV, treatment adherence plays an important role in treatment effectiveness and epidemic control. Studies of some infectious diseases indicate that patients who live closer to their health facilities maintain higher adherence; however, most models ignore the heterogeneity of patients' adherence. Clinics must balance knowledge about adherence with epidemic growth when creating successful treatment programs. We develop an optimization model that integrates a clinic's capacity decisions with population health outcomes. We find that incorporating adherence into clinic planning models can lead to decisions that significantly improve outcomes. For example, in a realistic case study of the HIV epidemic in Zambia, we find that decision makers who ignore decreasing adherence make suboptimal decisions and overestimate the effectiveness of their treatment programs by as much as 94%. Our model is a first step toward understanding the relationship between adherence and health delivery.