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United States Department of Agriculture

Agricultural Research Service

Research Project: MANAGEMENT TECHNOLOGIES FOR CONSERVATION OF WESTERN RANGELANDS

Location: Range Management Research

Title: The public water supply protection value of forests: A watershed-scale ecosystem services based upon total organic carbon

Authors
item Elias, Emile -
item Leband, David -
item Dougherty, Mark -
item Lockaby, Graeme -
item Srivastava, Puneet -
item Rodriguez, Hugo -

Submitted to: Open Journal of Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 18, 2014
Publication Date: June 1, 2014
Repository URL: http://handle.nal.usda.gov/10113/59430
Citation: Elias, E., Leband, D., Dougherty, M., Lockaby, G., Srivastava, P., Rodriguez, H. 2014. The public water supply protection value of forests: A watershed-scale ecosystem services based upon total organic carbon. Open Journal of Ecology. 4:517-531.

Interpretive Summary: Linked watershed and reservoir models were used with projected land use change to estimate the changes in TN, TP and TOC in a drinking water supply reservoir. The change in TOC was then evaluated using a cost-based methodology to estimate the water filtration services provided by forests in the watershed. The additional drinking water treatment cost following urbanization was $91-$91 per square km per day following urbanization.

Technical 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.

Last Modified: 11/26/2014
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