Methodologies for Calculating Baseline and Compliance Urban Per Capita Water Use was written with the assistance of the following consultants: Stephen Hatchett, Senior Economist, CH2M HILL Brian Van Lienden, Water Resources Engineer, CH2M HILL Anil Bamezai, Principal, Western Policy Research David Mitchell, Economist, M.Cubed The Urban Stakeholder Committee provided significant guidance in developing this document. The Department of Water Resources would like to thank the members for their help. Ernesto Avila California Urban Water Agencies Tim Barr Western Municipal Water District Joe Berg Municipal Water District of Orange County Tim Blair Metropolitan Water District David Bolland Association of California Agencies Lisa City of Roseville Heather Cooley Pacific Institute Mary Lou Cotton Kennedy/Jenks Consultants Jerry De La Piedra Santa Clara Valley Water District Edwin de Leon Golden State Water Company Chris Dundon Contra Costa Water District Penny Falcon Los Angeles Dept of Water & Power Sharon Fraser El Dorado Irrigation District Luis Generoso City of San Diego William Granger Otay Water District Richard Harris East Bay Municipal Utility District Jack Hawks California Water Association Bob Kelly Suburban Systems Dave Koller Coachella Valley Water District Nora Laikam City of Fresno Matthew Lyons Long Water Department Paul Selsky Brown and Caldwell Henry McLaughlin City of Fresno Jim Metropulos Sierra Club John Mills Offices of John S. Mills Lisa Morgan-Perales Inland Empire Utilities Agency Daniel Muelrath City of Santa Rosa Ron Munds City of San Luis Obispo Tom Noonan Ewing Irrigation Loren Oki University of California, Osann Natural Resources Defense Council Toby Roy San Diego County Water Authority Sanchez Irvine Ranch Water District Bob Wilkinson University of California, Santa Barbara John Woodling Sacramento Regional Water Authority Contents
Step 1. Baseline Water Use and Midpoint Year Whispering Glen Water District selected a 10-year baseline period of 1996-2005. The average base daily per capita water use for this period was calculated to be 228 GPCD. The savings are calculated based on water deliveries in the midpoint year of the baseline period, which is 2000. Step 2. Metering Savings (Equation 4) Deliveries to Unmetered Connections in Midpoint Baseline Year, gallons X 0.20 Metering Savings, GPCD 2,541,637,800 8.3 GPCD = = Service Area Population in Midpoint Baseline Year X 365 days 168,118 Step 3. Indoor Residential Savings Total Indoor Residential Savings, GPCD = Toilets Savings, GPCD + Toilets Savings, GPCD + Residential Washers Savings, GPCD + Residential Showers Savings, GPCD = 16.5 GPCD 7.6 1.6 6.0 1.3 Alternative 1, Target Method 4 Calculator: Alternative 2, Default: Total Indoor Residential Savings, GPCD = 15.0 GPCD Step 4. CII Savings (Equation 5) CII Savings, GPCD = Average baseline CII Water Use, GPCD X 0.10 = 6.9 GPCD 69.0
Step 5. Landscape Irrigation and Loss Savings (Equations 2 and 6) Landscape Irrigation and Water Loss Sector Use, GPCD = 2000 Base Daily per Capita Water Use – Standard Indoor Residential Use, GPCD – CII Deliveries in Midpoint Baseline Year, GPCD = 89.0 GPCD 227.7 70.0 68.7 Landscape Irrigation and Water Loss Savings, GPCD = Landscape Irrigation and Water Loss Sector Use, GPCD X 0.216 = 19.2 GPCD 89.0 Step 6. Total Savings Because are two alternative methods to calculate indoor residential savings, there are two alternatives for total savings, calculated using Equation 3. Alternative 1 (based on Target Method 4 Calculator for Indoor Residential Savings): Total Savings, GPCD = Metering Savings, GPCD + Indoor Residential Savings, GPCD + CII Savings, GPCD + Landscape Irrigation and Water Loss Savings, GPCD = 50.9 GPCD 8.3 16.5 6.9 19.2 Alternative 2 (based on default for Indoor Residential Savings): Total Savings, GPCD = Metering Savings, GPCD + Indoor Residential Savings, GPCD + CII Savings, GPCD + Landscape Irrigation and Water Loss Savings, GPCD = 49.4 GPCD 8.3 15.0 6.9 19.2 Step 7. 2020 Urban Water Use Target (Equation 1) Alternative 1 (based on Target Method 4 Calculator for Indoor Residential Savings):
Urban Water Use Target, GPCD = Base Daily per Capita Water Use, GPCD – Total Savings, GPCD = 176.8 GPCD 227.7 50.9 Alternative 2 (based on default for Indoor Residential Savings): Urban Water Use Target, GPCD = Base Daily per Capita Water Use, GPCD – Total Savings, GPCD = 178.3 GPCD 227.7 49.4 APPENDIX C Regulations for Implementing Process Water Provision California Code of Regulations 23. Waters