This report describes the investigation and appraisal of the flow and temperature of 100 springs in a 4,500- square-mile area comprising the Piedmont and Appalachian provinces of Maryland. The flow of these springs ranges from less than 1 to nearly 10,000 gallons per minute. The largest flow is from the Potomac Blue Spring in the Potomac River valley near Cumberland, Maryland. The flow of most springs ranges widely throughout an annual cycle, in some instances by as much as two orders of magnitude. All but 1 of 26 springs would be classed as variable to subvariable, according to a variability index proposed by Meinzer.