Section B, Data and Methods — Estimating Service Area Population Served

The data for the estimation of service area populations are developed in accordance with the requirements of Part D of the Water Use Permit Information Manual and are based on your public supply service area boundary.

We encourage you to first verify that your public supply service area map on file with the District is accurate and up-to-date.

Once you have verified the accuracy of your public supply service area, all you need is your dwelling units to be able to generate the required Functional Population Served estimate. Additional information is provided to also assist you in developing optional service area tourist and net commuter population estimates. Those seeking a detailed understanding of the functional population estimation or willing to perform calculations from the raw data are encouraged to review the full technical documentation and datasets.

For those considering a significant use deduction, the District has also made available the three-year average Districtwide percent industrial/commercial use (Section F). Please note that there are limitations on the combined use of certain per capita significant use deductions and tourist and net commuter populations. See Significant Use in Section 3.6 in “Part B” of the Water Use Permit Information Manual for details and limitations.

New and renewing water use permit applicants are encouraged to review the population projections available in sections C and D of the Utility Demographics page.

Section B-1

Quick calculation guide for estimating service area population

If your retail water service area has not changed in the past year and you are not interested in background information or verifying the District’s calculations, we have prepared a guide, below, that shows you how to generate population estimates using the population data by utility service area.

Section B-2

Utility data to complete Appendix C worksheets

This spreadsheet provides required and optional data at the service area level that are needed to estimate service area population using the required population methodology and worksheets outlined in Part D. All data are provided with the exception of year-of-interest dwelling units served (which must be supplied by the utility in Worksheet A — see Section B-3 below) and the number of public lodging rooms served (which may be identified by the utility as served from the District’s public lodging facilities layer in Section B-4). Provided data also includes optional net commuter population data.

Section B-3

Required Appendix C population estimation worksheets

Data from Section B-2 above may be entered directly into the required Appendix C Worksheets.

Section B-4

Public lodging facilities layer for estimation of tourist population

This is an ArcGIS layer in which location, address and rental unit data (e.g., number of rooms) for all licensed public lodging facilities have been updated and geocoded annually. Lodging unit (rooms) data on the facilities, if actually served by the utility, may entered in Worksheet G (see Section B-3 above) in order to estimate the tourist population of the utility service area.

ArcGIS users: Download the Public Lodging Facilities Layer  via the District’s Open Data Portal.

Non-GIS users: Use our Public Supply Service Areas Map Viewer. This map viewer may take a minute to open completely. Map viewer is not available from 10 p.m to 6 a.m. for maintenance.

Need help? This document will guide you on viewing your service area, obtaining lodging room data and, if not using the District-provided data, will also guide you on how to obtain census data for your retail water service area using the Map Viewer.

Section B-5

Population estimation methodology:
Technical documentation and data

This section will be of interest to those who would like either to estimate the “functional population served” not using District-supplied data or to gain a detailed understanding of the District’s methodology. Below, you will find the technical documentation for the methodology, survey minimum requirements, all Appendix C worksheets, seasonal resident and permanent population by ZIP Code, optional tourist and net commuter estimation materials, and the census variable layer.