FINAL Backup_Appendix C - Population, Employment, and Demand Projections — original pdf

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FINAL – Water Forward 2024 Appendix C APPENDIX C: POPULATION, EMPLOYMENT, AND DEMAND PROJECTIONS Integrated water resource planning provides a blueprint that ensures residents and businesses in Austin have sustainable access to clean water now and into the future. To properly plan and manage Austin’s water resources, it is critical to have a reasonable understanding and characterization of how and where water is currently used in the city as well as quantifiable estimates of how much water will be needed in the future. Appendix C.1 describes the primary tool used to characterize and explore water demands, referred to as the Disaggregated Demand Model (DDM). Using the tool, current water use is defined, as described in Appendix C.2, and future demand is projected, as described in Appendix C.3. These sections describe the City’s water demand at the water source (diversions), at the water treatment plant (pumpage), and at the Austin Water customers’ meters (consumption). C.1. Disaggregated Demand Model The foundation of the Water Forward 2024 water demand estimates is the underlying DDM, which evaluates historical demand, population, housing units, and employment and uses projections of future population, housing units, and employment to project future demands. The DDM was used to develop a range of demands based on high, medium, and low population and employment projections. The DDM provides the analytical environment for assessing potential water savings from conservation and reuse measures being evaluated during plan development. The DDM also includes functionality to assess water demands under future climatic scenarios and tracks water consumption by end uses, which informs the assessment of yield potential for decentralized supply options. The following sections describe the model’s attributes, primary data sources, and development. C.1.1. Demand Model Attributes The DDM is a data-driven Python tool that models water use by sector, subsector, and end use at geographic planning units for current demands as well as high, medium, and low demand projections for the key planning horizons of 2040, 2080, and 2120. Austin Water staff conducted this analysis using geographic units known as the Delphi, Trends, and Imagine Austin (DTI) polygons, which refers to Austin’s comprehensive plan, Imagine Austin. The DTI polygons divide the city into 235 geographic units. The area covered by the DTI polygons includes the City of Austin’s full and limited purpose jurisdictions, as well as the city’s extra-territorial jurisdiction, as shown in Figure C-1. The DDM provides an estimate of existing and future water demands by sector, subsector, and end use for each DTI polygon using baseline and projected population and employment, which are the primary drivers of water use in the City of Austin. C - 1 FINAL – Water Forward 2024 Appendix C Figure C - 1 Disaggregated Demand Model DTI Geographic Units. For analysis purposes, it is useful to group water demands according to similar user characteristics. Water demands are grouped into customer sectors, subsectors, and end uses, as shown in Figure C-2. Residential units, which are tied to population, are the basis of residential demands. Number of employees is the basis of commercial demands. The sectors included in the DDM are: • Single family residential (SFR) • Multi-family residential (MFR) • Wholesale customers (WS) university subsectors • City of Austin (COA) • Commercial (COM), which includes large volume customers in the industrial and C - 2 FINAL – Water Forward 2024 Appendix C Figure C - 2 Disaggregated Demand Model Sectors, Subsectors, and End Uses. C.1.2. Primary Data Sources The primary data sources for developing the DDM are described below: • DTI Polygons - Geographic unit of analysis for the DDM. The data include long-range population and employment forecasts produced by the City Demographer in conjunction with Austin Water, which have been disaggregated to a small-polygon level by Austin Water. The data also contain estimates of water service population, wastewater service population, and similar employment figures for 2020, as well as projections for 2040, 2080, and 2120. Both single family and multi-family population served estimates were developed by Austin Water for the DTI polygons. • ESRI Community Analyst Dataset - Dataset featuring a generally complete listing of employers within the City of Austin as well as pertinent data (number of employees, North American Industry Classification System code, sales volumes, etc.) for the year 2020. • Austin Water Billing Accounts and Consumption Data - Historical billing records (in the form of GIS feature point datasets) for every Austin Water customer from 2015 through 2020. • COA Building Permit Data - All approved building permit data provided by the City’s Development Services Department in the form of a database (the Application Management and Data Automation database known as AMANDA) and shapefiles of permits by year. C - 3 FINAL – Water Forward 2024 Appendix C • 2020 Land Use GIS polygon - GIS layer produced by the City of Austin Planning Department that indicates land use types. This geographic unit of analysis was used to look for inconsistencies between the billing point rate classes and land use types. Edits were made to the billing dataset and the land use layer where appropriate so that they matched each other (i.e. single family accounts on single family land use parcels, commercial accounts on commercial parcels, etc.). • 2020 Census – Data collected by the US Census Bureau, containing estimates of population, housing units, occupancy, and other demographic information. • County Appraisal District – Travis, Williamson, and Hays appraisal district data includes spatial information about ownership and land use classification that were also used to look for inconsistencies in billing point rate classes and to provide information where COA Land Use data was not available. • City of Austin Address Points – GIS data providing address information for parcels across the City. • Service Extension Request (SER) Data – data including GIS polygons and information about potential developments, including development type and estimates of the amount of water a development may need provided in terms of living unit equivalents, or the amount of water typically used by one single family home. C.1.3. Model Input Development C.1.3.1. Baseline and Projected Population, Units, and Employment Census blocks within the DTI polygons were used to create a baseline estimate of housing units and population estimates in each polygon, as seen in Table C - 1. An employment population dataset, ESRI Community Analyst, was used as a reference for baseline estimates of employees and business type within each DTI polygon. Table C - 1 Historical Served Population for Austin Water Service Area. Year 2015 2016 2017 2018 2019 2020 Served Population 977,500 1,006,600 1,033,000 1,055,800 1,065,500 1,064,700 Population and employment projections were then developed for three planning horizons: 2040, 2080, and 2120. The population projections were developed in conjunction with the City of Austin Demographer using a control total approach, which assumed the recent historical population growth would continue with a gradual decay factor over the coming 100 years. High, C - 4 FINAL – Water Forward 2024 Appendix C medium, and low projections for population were developed to represent a range of possible futures, as seen in Table C - 2. Employment projections were developed assuming a similar ratio of population to employees though the planning horizons. Table C - 2 Long Range Population Forecast for Austin Water Planning Area. Year 2040 2080 2120 Low Projection Medium Projection High Projection 1,454,500 2,301,800 2,865,400 1,524,200 2,457,700 3,209,300 1,554,100 2,580,200 3,571,300 COA Building Permit Data and Service Extension Requests for utilities were aggregated and sorted based on the likelihood that a proposed development would be completed. Austin Water staff then used the development data and insights to distribute added population and employees throughout the planning area. C.1.3.2. Baseline and Projected Water Use The DDM uses a bottom-up approach that relies on detailed, account-level billing data from 2015 through 2020. For each active account, the DTI polygon location was identified. Customer types and rate codes, along with County Property Appraisal land use classifications, were used to determine the water use sector of the account. All billing sets were normalized to calendar month usage using the daily average of the billing cycle and the number of days in the billing cycle that occurred in each calendar month. Water use data were then aggregated by subsector, DTI polygon, and month. Using the DTI polygon data for housing unit and employment estimates and the aggregated water use, water use factors (WUFs) were calculated for each polygon for each year. Water use for single and multi-family residential customers was based on residential units within those housing types, while commercial and City of Austin water use was based on employment within the sector. Base year WUFs from the average of 2015 through 2020 water use data for each sector/subsector and DTI were calculated and used as the starting point of the forecast. Historical water billing data was classified into customer sectors and subsectors, and then sector or subsector annual water usage was aggregated to the DTI polygon level. This annual total was then divided by either the appropriate number of units or employees, depending on the sector or subsector, to develop the WUFs. In this fashion, WUFs were calculated for each customer class of Austin Water: single family, multi-family, commercial, wholesale, and City of Austin. Residential customer WUFs are presented as amount of water consumed per housing unit, while non-residential customer WUFs are presented as amount of water consumed per employees. To account for annual fluctuations in demand, a time series regression analysis was carried out for each sector/subsector at the utility level to assess the impact of weather and the COVID pandemic on water demand, as well as to quantify time series trends in the WUFs. The results of this regression analysis served to adjust the base year WUF for average weather conditions and to neutralize for the impacts of the COVID pandemic. The COVID pandemic had a significant impact on water demands in 2020, with residential sectors generally showing an increase in water demand, and commercial sectors generally showing a decrease in water C - 5 FINAL – Water Forward 2024 Appendix C demand. Following the adjusted base year WUFs, the time series trend from the regression analysis was used to arrive at projection WUFs which continued the observed historical trend into the future. This trending served as a means of accounting for passive replacement of water using devices and other underlying development, demographic, and behavioral trends. Given the uncertainty surrounding these trends, a conservative estimate of 50% of the historical trends was used to project changes in the WUFs over time. The incorporation of the weather and COVID normalized base year WUFs, along with 50% of the historical trend serves as the basis for the baseline water demand scenario in the DDM. The baseline scenario, which reflects baseline levels of conservation and water reuse, was included in the identification of baseline water supply needs. The DDM allows for these projected WUFs to be further adjusted based on the anticipated impact of active water conservation and reuse strategies for other analysis scenarios. Water demand was calculated and projected as the mathematical product of the sector/subsector base year WUF and the count of housing units or employees for each DTI for each planning year. C.1.3.3. End Use Projections of Water Use Austin Water staff used estimates of the percentage distribution of indoor water use among specific end uses of water for each sector as inputs for the DDM. End use ratios were developed for the single family residential, multi-family residential, and commercial sectors. Starting with the indoor/outdoor split, in instances where dedicated irrigation meters were present on a parcel, all the water use from these meters were taken to be outdoor water use, while the remaining non-irrigation meters were taken to be indoor use. For customers without dedicated irrigation meters, the industry standard minimum month method was used to estimate the portion of monthly water demands that are used for outdoor watering. Specifically, the lowest water use month for each sector/subsector within each DTI was identified and multiplied by 12 to estimate the total annual indoor water use. The difference between the total water use and the calculated indoor water use was identified as annual outdoor water use. To estimate current single family residential indoor end uses, Austin Water staff did research to identify and use best available data sources. The Water Research Foundation’s 2016 Residential End Uses of Water, Version 2 Report (DeOreo et. Al, 2016) informed the indoor end uses for single family residences. Austin Water staff developed the multi-family residential and commercial indoor end uses based on a comprehensive literature review of available information coupled with insight and guidance from other City of Austin staff. The literature review conducted to identify relevant estimates of indoor water use by end use among the multi- family and commercial sectors included the following studies: • CDM Smith. (2016). Los Angeles Department of Water and Power (LADWP) • Aqucraft. (2011). Embedded Energy in Water Studies Study 3: End-use Water Demand • University of Arizona Water Resources Research Center (WRRC). (2007). City of Conservation Potential Study. Profiles. Tucson Water Use. • Gleick, P. A. (2003). Waste Not, Want Not: The Potential for Urban Water Conservation C - 6 FINAL – Water Forward 2024 Appendix C in California. Water. • EPA. (2016). EPA WaterSense - Commercial Buildings. • Water Research Foundation (WRF). (2000). Commercial and Institutional End Uses of Table C - 3 shows the distribution of indoor water by end use for the single family and multi- family residential sectors used in the DDM. Table C - 3 Distribution of Indoor Water Use for the Residential Sectors. Indoor End Use Showers/Baths Toilets Clothes Washers Dishwashers Faucets/Basins Leaks Single Family Residential Multi-Family Residential 23.9% 18.1% 17.0% 1.8% 19.5% 19.8% 20.3% 23.9% 13.7% 1.1% 20.8% 20.2% Indoor End Use Medical Equipment Pools Laundry Kitchens HV/AC Domestic Misc. Table C - 4 shows the distribution of indoor water by end use for each commercial (including large volume) subsector used in the DDM. Table C - 4 Distribution of Indoor Water Use for the Commercial Subsectors. Hospitals Offices Schools Restaurants Hotels Retail Industrial Large Volume Universities Large Volume Industrial Commercial Subsectors 13.0% 0.0% 3.0% 5.0% 0.0% 0.0% 0.0% 5.8% 34.0% 36.3% 35.0% 10.0% 43.5% 14.4% 0.0% 0.0% 2.0% 7.9% 8.7% 66.0% 15.3% 0.0% 0.0% 0.0% 0.1% 0.0% 15.2% 48.2% 14.8% 0.0% 0.0% 0.0% 9.2% 1.3% 11.4% 23.2% 37.4% 13.1% 41.3% 52.1% 17.1% 15.5% 0.0% 0.0% 0.0% 0.0% 48.0% 10.5% 41.5% 1.1% 0.3% 5.9% 2.3% 40.6% 29.5% 20.3% 0.0% 0.0% 0.0% 5.0% 10.0% 10.0% 75.0% C.2. Historic Baseline Water Use From baseline estimates calculated using the average diversions from year 2015 to 2020, Austin Water and its customers used an average of approximately 148,900 acre-feet of raw water diversions each year. The historic baseline total pumpage of treated water into the distribution system per year was approximately 98% of diversions. The difference between raw water diversions and treated water pumpage is attributable to several factors including use of some of that water in the treatment process itself, water loss due to evaporation, and metering differences. Historic baseline amounts of water consumed by Austin Water and its customers was approximately 83% of diversions. The difference between treated water pumpage and C - 7 FINAL – Water Forward 2024 Appendix C consumption makes up non-revenue water (NRW). Some NRW is lost through leaks in pipes on its way to customers, while other components of NRW include water used for flushing or fighting fires. Historic baseline NRW made up about 15% of the historic baseline estimate of raw water diversions. See Table C - 5 for a summary of the historic base year average water demands by sector. Table C - 5 Historic Baseline 2015-2020 Average Water Demands by Sector. i t Sector SFR n MFR o COM WS COA Total p m u s n o C NRW Pumpage Diversions Base Year Demands (Acre-Feet/Year) Base Year Demands As % of Diversions 28% 22% 26% 5% 1% 83% 15% 98% 100% 42,200 32,300 38,800 7,800 2,100 123,300 22,400 145,700 148,900 Residential (single family and multi-family) water use accounted for about 60% and commercial water use accounts for about 32% of all water consumed by the City of Austin (Table C - 4). Figure C - 3 Historic Baseline 2015-2020 Average Water Consumption by Sector. Figure C-5 shows the complete breakdown of historic baseline water consumption for all sectors and their end uses for the years 2015-2020. C - 8 FINAL – Water Forward 2024 Appendix C Figure C - 4 Historic Baseline 2015-2020 Average Water Consumption End Use Breakdown. C.2.1. Single Family and Multi-Family Residential Single family residential customers consumed a baseline of approximately 42,000 acre-feet of water, or 28% of total raw water diversions, while multi-family residential customers consumed a baseline of approximately 32,000 acre-feet of water, or 22% of raw water diversions. Outdoor water use is estimated to be 31% of all single-family residential use and 18% of all multi-family residential historic baseline water use (Figure C - 5). C - 9 FINAL – Water Forward 2024 Appendix C Figure C - 5 Residential Sector Historic Baseline Consumption Indoor/Outdoor Breakdown. Figure C - 6 shows a schematic for the average yearly residential consumption in gallons of water consumed per person for the base years of 2015-2020. C - 10 FINAL – Water Forward 2024 Appendix C Figure C - 6 Historic Baseline 2015-2020 Residential Water Consumption Per Person Schematic. C.2.2. Commercial and Large Volume Commercial Commercial customers consumed a historic baseline of approximately 38,000 acre-feet of water, or 26% of raw water diversions. Commercial water use is divided across seven subsectors: hospitals, hospitality services, industrial, offices, restaurants, retail/commerce, and schools & universities. The breakdown of baseline commercial consumption is shown in Figure C - 7. Austin Water classifies some of its customers as large volume commercial customers. These customers consume more than 261 acre-feet of water per year and include several large industrial customers, such as Samsung Semiconductor, as well as the University of Texas at Austin. Large volume commercial water use is estimated to be 29% percent of all historic baseline commercial consumption. C - 11 FINAL – Water Forward 2024 Appendix C Figure C - 7 Commercial Historic Baseline Consumption Subsector Breakdown, including Large Volume Commercial Customers Figure C - 8 shows a schematic for the average yearly commercial consumption in gallons of water consumed per employee for the base years of 2015-2020. C - 12 FINAL – Water Forward 2024 Appendix C Figure C - 8 Historic Baseline 2015-2020 Commercial Water Consumption Per Employee Schematic. C.2.3. City of Austin and Wholesale The City of Austin’s historic baseline consumption was approximately 2,100 acre-feet of water, or 1% of raw water diversions. The City’s outdoor water use is estimated to be about half of its indoor water use (Figure C - 9). C - 13 FINAL – Water Forward 2024 Appendix C Figure C - 9 City of Austin Historic Baseline Consumption Indoor/Outdoor Breakdown. Austin Water wholesale customers used a baseline of approximately 7,800 acre-feet of water, or 5% of raw water diversions. Single family residential water use accounts for about 69% of wholesale customer use, multi-family residential water use accounts for about 12%, and commercial water use accounts for about 19% of all water consumed by the City’s wholesale customers in the historic baseline (Figure C - 10). Figure C - 10 Wholesale Historic Baseline Consumption Sector Breakdown. C - 14 FINAL – Water Forward 2024 Appendix C C.3. Future Baseline Water Demand Projections Future baseline water demands are based on an average of the base years of 2015-2020 water consumption (adjusted for weather, COVID, and historical trends) and represent future conditions based on projections of population, housing units, and employment in Austin. The base years were chosen to represent average year demands. Future baseline water demands also incorporate projected passive conservation, which can result from reductions in water use from existing conservation, continued improvements primarily in indoor water using fixture efficiencies, and changes to plumbing and/or housing code that would impact future water use. These passive conservation trends were analyzed per sector and used to develop percent reductions to indoor and outdoor water demand. These passive reductions in water use were then applied to each of the planning horizon years (2040, 2080, and 2120) as a percent reduction in the WUF for the year of interest. As shown in Figure C - 11, without potential future water strategies in a medium projection scenario, 2120 treated water pumpage is projected to be 429,500 acre-feet to serve a projected population of about 3,210,000. Austin’s corresponding future baseline water diversion projection is 444,500 acre-feet by 2120, which accounts for water used in the water treatment process. It is important to note that future baseline water demands do not include future conservation savings from additional conservation programs, codes, or ordinances. Additionally, future baseline demands do not reflect reductions in potable water demand due to future increases in centralized, decentralized, and onsite water reuse. The future baseline results of the DDM are meant to be a starting place to assess the various conservation, reuse, and supply strategies considered in the Water Forward planning process. Demand projections that incorporate the implementation of Water Forward 2024 strategies show a marked decrease from future baseline demands. Additional details on savings from Water Forward Plan recommendations can be found in Appendix J. Figure C - 11 Baseline Water Pumpage with Population to 2120 in a Medium Projection Scenario. Table C - 6 presents the future baseline water demands by sector for low, medium, and high C - 15 FINAL – Water Forward 2024 Appendix C projection scenarios. Figure C - 12 presents the future baseline water demands by sector for a medium projection scenario. Future baseline system pumpage is projected to grow by 226% from its current level over the next 100 years. Again, this projection does not include projected effects of water use savings of potential future conservation, reuse, or other strategies that may be included in the Water Forward 2024 plan. Water use of the residential sector (single family and multi-family) is expected to grow about 206% over the next 100 years, while the commercial sector’s water use growth rate of nearly 211% over the next 100 years captures the trend that employment is projected to grow at a rate greater than population served. Table C - 6 Baseline Future Water Demand Projections by Sector. Future Water Demands (Acre-Feet/Year) Low Projection Scenario Medium Projection Scenario High Projection Scenario Sector 2040 2080 2120 2040 2080 2120 2040 2080 2120 56,700 82,200 95,200 53,200 85,900 108,900 58,600 86,600 104,100 60,500 91,300 114,400 55,200 91,600 123,800 57,300 97,700 141,500 COM 55,400 94,500 110,800 56,800 98,200 120,600 58,100 102,200 131,400 9,600 2,800 11,400 12,900 4,000 5,200 9,600 2,800 11,400 12,900 4,000 5,200 9,600 2,800 11,400 12,900 4,000 5,200 Total 177,800 278,000 332,900 183,000 291,900 366,500 188,300 306,600 405,400 NRW 34,900 47,900 57,800 34,000 50,100 63,000 34,900 52,400 69,100 Pumpage 212,700 325,900 390,700 217,000 342,000 429,500 223,200 359,000 474,500 Diversions 220,100 337,300 404,400 224,600 354,000 444,500 231,000 371,600 491,100 SFR MFR WS COA n o i t p m u s n o C C - 16 FINAL – Water Forward 2024 Appendix C Figure C - 12 Future Baseline Demand Projections for a Medium Projection Scenario to 2120. Figure C - 13, Figure C - 14, and Figure C - 15 show the breakdown of future baseline water consumption per year for all sectors and their end uses for the planning years of 2040, 2080, and 2120, respectively, in a medium projection scenario. C - 17 FINAL – Water Forward 2024 Appendix C Figure C - 13 Future Baseline Water Consumption Breakdown for 2040 in a Medium Projection Scenario. C - 18 FINAL – Water Forward 2024 Appendix C Figure C - 14 Future Baseline Water Consumption Breakdown for 2080 in a Medium Projection Scenario. C - 19 FINAL – Water Forward 2024 Appendix C Figure C - 15 Future Baseline Water Consumption Breakdown for 2120 in a Medium Projection Scenario. Figure C - 16, Figure C - 17, and Figure C - 18 provide future baseline medium projection schematics of residential consumption in gallons consumed per person for the planning years of 2040, 2080, and 2120, respectively. C - 20 FINAL – Water Forward 2024 Appendix C Figure C - 16 Future Baseline 2040 Medium Projection Residential Water Consumption Per Person Schematic. C - 21 FINAL – Water Forward 2024 Appendix C Figure C - 17 Future Baseline 2080 Medium Projection Residential Water Consumption Per Person Schematic. C - 22 FINAL – Water Forward 2024 Appendix C Figure C - 18 Future Baseline 2120 Medium Projection Residential Water Consumption Per Person Schematic. Figure C - 19, Figure C - 20, and Figure C - 21 provide future baseline medium projection schematics of commercial consumption in gallons consumed per employee for the planning years of 2040, 2080, and 2120, respectively. C - 23 FINAL – Water Forward 2024 Appendix C Figure C - 19 Future Baseline 2040 Medium Projection Commercial Water Consumption Per Employee Schematic. C - 24 FINAL – Water Forward 2024 Appendix C Figure C - 20 Future Baseline 2080 Medium Projection Commercial Water Consumption Per Employee Schematic. C - 25 FINAL – Water Forward 2024 Appendix C Figure C - 21 Future Baseline 2120 Medium Projection Commercial Water Consumption Per Employee Schematic. C - 26 FINAL – Water Forward 2024 Appendix C References Aquacraft Inc. (2009). Embedded Energy in Water Study 3: End-Use Water Demand Profile. UC Berkeley: California Institute for Energy and Environment. Embedded Energy in Water Study 3 Hourly Profiles FINAL.XLS DeOreo, W.B., Mayer, P., Dziegielewski B., Kiefer J. (2016). Residential End Uses of Water, Version 2. Water Research Foundation. Residential End Uses of Water, Version 2: Executive Report EPA. (2024). Commercial and Institutional Sector. EPA. Types of Facilities | US EPA Gleick, P., Haasz, D., Henges-Jeck, C., Cushing, K. K., Mann A. (2003). Waste Not, Want Not: The Potential for Urban Water Conservation in California. Pacific Institute. Waste Not, Want Not: The Potential for Urban Water Conservation in California Los Angeles Department of Water & Power, CDM Smith. (2017). Water Conservation Potential Study. Water Conservation Study June 2018.pdf Mayer, P. W., DeOreo, W. B., Opitz E. M., Kiefer J. C., Davis W. Y., Dziegielewski, B., Neson, J. O. (2000). Residential End Uses of Water. AWWA Research Foundation and American Water Works Association. Residential End Uses of Water University of Arizona Water Resources Research Center. (2007). Water Use by Sector in Tucson Water’s Service Area. City of Tucson. Water Use by Sector C - 27