TITLE:
The Public Water Supply Protection Value of Forests: A Watershed-Scale Ecosystem Services Analysis Based upon Total Organic Carbon
AUTHORS:
Emile Elias, David Laband, Mark Dougherty, Graeme Lockaby, Puneet Srivastava, Hugo Rodriguez
KEYWORDS:
Ecosystem Services, Water Quality, Drinking Water Treatment, Urbanization, Land Use Change
JOURNAL NAME:
Open Journal of Ecology,
Vol.4 No.9,
June
9,
2014
ABSTRACT: We developed a cost-based methodology to assess the value of forested
watersheds to improve water quality in public water supplies. The developed
methodology is applicable to other source watersheds to determine ecosystem
services for water quality. We assess the value of forest land for source water
mitigation of total organic carbon (TOC) through the use of linked watershed
and reservoir simulation models and cost-based valuation economics. Watershed
modeling results indicated that expected urbanization will increase TOC loads
to Converse Reservoir (Mobile, AL). Reservoir model results indicated that
future median TOC concentrations increased by 1.1 mg·L-1 between
1992 and 2020 at the source water intake. Depending upon dynamic reservoir TOC
concentrations, additional drinking water treatment with powdered activated
carbon (PAC) often is necessary between May and October to comply with Safe
Drinking Water Act regulations. The cost for additional treatment was
calculated using minimum and maximum volume treated with simulated TOC
concentrations at the source water intake. Daily simulated TOC concentrations
for the base scenario using 1992 land cover (3% urban) were compared with
simulated TOC concentrations following forest to urban land conversion
predicted in the watershed by 2020 (22% urban). The daily cost for additional
drinking water treatment with PAC was calculated if simulated TOC
concentrations exceeded 2.7 mg·L-1. The mean increase in
daily treatment costs between base and future scenarios ranged from $91 to $95
per km2 per day for forest land water purification ecosystem
services.