Since the publication of the Millennium Ecosystem Assessment (MEA 2005), awareness has steadily grown regarding the importance of maintaining natural capital. Forest vegetation is a valuable source of natural capital, and the regulation of water quantity and quality is among the most important forest ecosystem services in many regions around the world. Changes in forest cover alter the provision of water resource ecosystem services via influences on precipitation regimes, drinking water supply and purification, flood control, maintenance of streamflows, provision of recreational opportunities, and cooling water for thermoelectric power production. In this chapter, we describe how the ecosystem service values of water resources from forest landscapes can be estimated. Although much of the literature we reference is focused on the Southern United States, the concepts and methods described here are broadly applicable to other regions.