Estimating the Public Water Supply Protection Value of Forests

Abstract

We developed a methodology to assess the economic value of forested watersheds to improve water quality for public supplies. The interdisciplinary approach required collaboration between economists, municipal water managers, regional growth planners, hydrologic and water quality modelers. Data used in this project were derived from federal, state and local entities. We used regional growth projections with linked watershed and reservoir simulation models and cost‐based valuation economics. Additional treatment cost to comply with Safe Drinking Water Act regulations was calculated using volume treated and simulated total organic carbon (TOC) concentrations. Simulated base TOC concentrations (3 percent urban) were compared with TOC concentrations predicted by 2020 (22 percent urban). Mean increase in daily treatment costs ranged from $91 to $95 per km 2 per day. The developed methodology is applicable to other watersheds to estimate water purification ecosystem services and is recommended for use in future interdisciplinary modeling courses.