ECONOMIC LINKAGES BETWEEN COASTAL WETLANDS AND WATER QUALITY: A REVIEW OF VALUE ESTIMATES REPORTED IN THE PUBLISHED LITERATURE

Abstract

This manuscript summarizes a total of 12 peer-reviewed studies, published from 1981 to 2001, reporting 28 separate estimates for the disaggregate2 value of water quality services provided by coastal and non-coastal wetlands. Estimates ranged across three orders of magnitude and are highly dependent on the specific geographic site providing the service, the type of water quality service provided, the measurement technique, and whether locally derived benefits were calculated to extend across all existing wetlands. Considering only coastal zone wetlands across all study categories, the value of water quality services ranged from $2.85/acre/year to $5,673.80/acre/year, with a mean and median of $825.04/acre/year and $210.93/acre/year, respectively. The large difference between the mean and median value reflects the non-normal distribution of the estimates, and in particular the influence of a few very high values. Eliminating the most extreme outliers from the calculations generated mean and median values of $323.05/acre/year and $178.64/acre/year, respectively. By comparison, reported estimates of willingness-to-pay (WTP) values for wetland water quality services were relatively consistent across studies, ranging from $41.71 to $101.81, with a mean and median of $66.59 and $63.19, respectively. The apparent importance of geographic location, and the specific use demand, on water quality service value suggests that this facet of coastal wetland benefits needs to be carefully examined within a spatially disaggregated context.