Calculation of the Environmental Benefits of Water Conservation BMP’s

1. Katie Coughlin, Ph. D. Lawrence Berkeley National Lab kcoughlin@lbl.gov Calculation of the Environmental Benefits of Water Conservation BMP’s • LBNL Team • Robert Van Buskirk • Camilla Dunham-Whitehead • Peter Chan • Chris Bolduc • UC Berkeley • Michael Hanemann CUWCC Workshops September 20-21 2006

2. Outline • Conceptual Discussion • Definition of environmental benefits as an avoided cost • Assumptions and constraints imposed by the modeling framework • Ecological impacts and environmental values • Model Application • Model organization and output • Model input and interaction with the Avoided Cost model • Example Calculations • Questions and Discussion

3. Conceptual Discussion:Definition of environmental benefits as an avoided cost • Calculate value in $/volume of environmental benefits of reduced water use • The environmental benefit (EB) valuations can then be included in the cost-benefit analysis of water conservation BMP’s • Look at direct benefits of reduced raw water withdrawals which are not already accounted for in other environmental programs • Two exceptions: avoided cost of waste-water treatment for urban run-off; environmental benefits of reduced energy use for system operations • Like all avoided costs, this value is hypothetical, i.e. one must make numerous assumptions about the future • Philosophical issues related to monetization of environmental impacts are not part of this project

4. Conceptual Discussion:Assumptions and constraints • Requirements for this project include: • User inputs annual or seasonal water savings; no environmental data required • Model should cover all of CA and be “generic” • Compatibility with AC model • No double counting • Use data from literature reviews • Allow users to modify all default data values • These impose constraints on the model: • Use annual average environmental data • Benefits are product of environmental impact and economic value • No accounting for water year type • Limited spatial resolution (hydrologic regions) • Doesn’t model system operations • Doesn’t consider water transfers • Focus on accounting: all regions, services and sources • This type of integrated calculation has not been done before

5. Geographic resolutionCalWater 2.2 Hydrologic Regions

6. Conceptual Discussion:Environmental (ecological) impacts • EB=unit environmental impact * economic value per unit • Ecological impacts are defined in terms of services: maintenance of fish populations; maintenance of wetlands; improved water quality • UEI = fraction*(service per unit volume of water) • Fraction = probability that a unit of water saved at a source will be used by a particular service • Use the most basic, robust physical parameters to define the relationship between service and water availability • Account for seasonal variation in water requirements • Depends on water source type and location

7. Unit Environmental impacts • Determine the relationship between environmental service and water availability • Express as unit impact per acre-foot • Multiply by fraction for this service to get net impact per unit of saved water

8. Conceptual Discussion:Economic values • EB=unit environmental impact * economic value per unit • Units are $/service unit • Economic values can be market or non-market • Market values exist in the form of prices paid for land acquired expressly to restore riparian or wetland habitat • Non-market values are drawn from the available literature and focus primarily on recreational uses such as fishing • Urban runoff: use wastewater treatment costs • Energy benefits: use emissions permit prices • No geographic variation

9. Data Sources • Fish habitat (4.2.4) • Populations and Regional Distribution: NOAA-NMFS West Coast Salmon Biological Review Team Report (2003) and Calfish www.calfish.org • Flow data: CADWR water plan • Economic values: BASES study; Sportfishing Values Database www.indecon.com/fish/signin.asp • Riparian habitat (4.2.2) • River data: California Rivers Assessment www.ice.ucdavis.edu/newcara • Flow fractions: DWR water plan • Species distributions: California Natural Diversity Database www.dfg.ca.gov/whdab/html/cnddb.html • Evapotranspiration rates: CIMIS • Species water needs: California Native Plant Society www.cnps.org • Economic values: purchases for conservation and restoration • Wetlands (4.2.3) • Flow fractions: DWR water • Water requirements: USBR-DWR CALSIM II demands data; LBNL (N. Quinn) spreadsheet model • Economic values: purchases for conservation and restoration

10. Data Sources • Reservoir and lake recreation (4.2.1) • Average seasonal storage: California Data Exchange Center www.cdec.org • Storage-area relation: USBR-DWR CALSIM II data • Visitation rates, visitation elasticity, economic values: QED studies from 1980 • Economic values: BASES study at www.indecon.com/fish/signin.asp • Interagency Ecological Program quarterly reports iep.water.ca.gov • California Natural Diversity Database www.dfg.ca.gov/whdab/html/cnddb.html • California Native Plant Society www.cnps.org • San Francisco Bay Salinity (4.2.5) • Flow-salinity data: DWR Dayflow model • Species distributions: Interagency Ecological Program quarterly reports iep.water.ca.gov • Salinity impacts: Kimmerer et al. studies • No economic value data • Energy Benefits • User input of energy intensity and energy/emissions costs • Urban runoff • User input of runoff fractions and wastewater treatment costs