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

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

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

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

Geographic resolution CalWater 2.2 Hydrologic Regions

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

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

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

Data Sources Fish habitat (4.2.4) Populations and Regional Distribution: NOAA-NMFS West Coast Salmon Biological Review Team Report (2003) and Calfish Flow data: CADWR water plan Economic values: BASES study; Sportfishing Values Database Riparian habitat (4.2.2) River data: California Rivers Assessment Flow fractions: DWR water plan Species distributions: California Natural Diversity Database Evapotranspiration rates: CIMIS Species water needs: California Native Plant Society 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

Data Sources Reservoir and lake recreation (4.2.1) Average seasonal storage: California Data Exchange Center Storage-area relation: USBR-DWR CALSIM II data Visitation rates, visitation elasticity, economic values: QED studies from 1980 Economic values: BASES study at Interagency Ecological Program quarterly reports iep.water.ca.goviep.water.ca.gov California Natural Diversity Database California Native Plant Society San Francisco Bay Salinity (4.2.5) Flow-salinity data: DWR Dayflow model Species distributions: Interagency Ecological Program quarterly reports iep.water.ca.gov 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