We built a web-based tool to assist public health officials in designing their sentinel surveillance site network. Through simulation, we show that the sites our tool selects allow for better representation of disease burden. We also show that selecting the correct ICD-9 codes that the surveillance network should consider may be as important as selecting the locations of the sites themselves. Using our methods, we can help public health officials design surveillance systems, which are smaller and more easily managed but still detect cases that reflect reliable estimates of both disease burden and timing. 