Proposed Expansion of SWUCA Public Supply Requirements

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Proposed Expansion of SWUCA Public Supply
Requirements

• Jay Yingling, Senior Economist
• June 5, 2007

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Overview

• Background
• Service area delineation requirements
• Per capita calculation deductions reuse/desal
• Per capita calculation significant use
  deductions
• Per capita calculation service area population
  methodology
• Per capita compliance
• Residential water use reporting
• Reclaimed/stormwater reporting
• Open discussion
• Next steps

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Background

• Desire to standardize per capita calculations
  before considering revisions to standards
• Make NTBWUCA deductions consistent with rest of
  District
• Clarify and standardize significant use
  deductions
• Standardize current year population estimation
  methodology and documentation
• Desire to standardize per capita reporting
  requirements and compliance
• Desire to standardize and keep service area
  delineations and data current

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Service Area Delineation Reporting Requirements

• Service area more precisely defined
• Revisions must be relative to map in District
  layer
• Must delineate non-served areas (including
  definable areas served by domestic wells)
• Update map, contact, sales and purchases
  information at least every six years

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Proposed Per Capita Calculation

• GPCD (withdrawals imports - exports
  treatment loss significant uses environmental
  mitigation) / functional population
• New for northern counties are addition of
  significant use deductions and SWUCA population
  methodology
• New for NTBWUCA are revised significant uses,
  loss of reuse/desal credit and change to SWUCA
  population methodology

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Per Capita Reporting

• Will go from optional to required for utilities
  in northern counties with permitted average equal
  to or greater than 100,000 gpd
• Already required in all WUCAs
• May be reported on annual Public Supply survey

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Significant Use Deductions

• Per capita water demand should reflect the
  population-related demands of the service area
  such as residences, K-12 schools, recreation,
  local government and businesses that serve the
  local service area population.
• Significant use deductions are designed to allow
  you to deduct all or part of uses, such as large
  manufacturing, regional government and health
  centers and universities that serve a much
  broader population than the service area
  population.

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Significant Use Deductions

• Single significant uses
• I/C use in excess of District average
• Combined regional government and higher education
  facilities
• Individual regional health facilities
• I/C facilities where the primary ingredient is
  water

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Significant Use Deductions

• Conservation plans must be developed for deducted
  significant uses
• May not take some deductions if net commuter
  population is claimed (cant claim population and
  deduct use!)
• May not take all deductions (like single
  significant uses and I/C use in excess of
  District average)

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Population Issues (Outside SWUCA)

• Variety of population methodologies used
• Estimation of seasonal population is optional
• All households assumed permanent by some
• Some utilities seasonally adjust incorrectly
  inflating permanent resident estimates
• No allowance for seasonal resident outdoor use
  when away

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Population Issues (Outside SWUCA)

• No standardized methodology to estimate tourist
  populations
• No current allowance for other water use by
  tourist population
• No standardized methodology to estimate commuter
  population

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Proposed Population Rule Revisions

• Required population permanent, seasonal and
  group quarters population
• Tourist population estimation optional but
  methodology prescribed
• Net commuter population optional but methodology
  prescribed
• Data and calculations must be documented on
  required worksheets

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Features of New Methodology - Permanent and
Seasonal Population

• Requires calculation of both permanent and
  seasonal resident population to improve equity
  between utilities with large and small seasonal
  populations.
• Uses zip code level hospital admissions data to
  calculate service area seasonal resident peak
  population.
• Provides default seasonal resident
  persons-per-household value and residency
  duration.

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Features of New Methodology - Permanent and
Seasonal Population (Continued)

• Provides optional methodology for conducting
  surveys to determine seasonal resident
  population, persons-per-household, and residence
  duration
• Uses Census data tailored to service area for
  more accurate calculation of permanent resident
  persons-per-household data
• Ratios need only be calculated every ten years or
  when service area changes

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Features of New Methodology - Permanent and
Seasonal Population (Continued)

• Utilizes ratios of Census and hospital admissions
  data and served housing unit data
• Census data readily available on District and
  Census websites select Census blocks in service
  area
• District provides seasonal and permanent resident
  data by zip code on District website select
  ZCTAs in service area
• Seasonal resident ratio data used to divide
  service area households into permanent and
  seasonal households without having to conduct
  seasonality surveys

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Seasonal Resident Ratio Use of Hospital
Admissions Data to Estimate Seasonal Residents

• Uses difference between Census era average first
  quarter (Jan, Feb, Mar) and third quarter (Jul,
  Aug Sep) admissions
• for patient residence zip codes in service area
• Census era Census-1, Census, Census1
• for patients age 55 84
• emergency admissions only

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Seasonal Resident Ratio Census Era Seasonal
Populationfor Selected ZCTAs in Service Area

• (Avg Q1 admissions Avg Q3 admissions) /
  probability of admissions seasonal population
• Probability of admissions 0.015302
• Example ZCTA seasonal population
  (265/3 205/3) / 0.015302
  1,307

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Seasonal Resident Ratio Census Permanent
Populationfor Selected ZCTAs in Service Area

• Sum the Census population in households for the
  ZCTAs in the service area.
• Example ZCTA population in households 10,439

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Calculation of Census Era Seasonal Resident Ratio

• Seasonal resident ratio (Census era estimated
  seasonal population Census population in
  households) / Census population in households for
  service area zip code(s)
• Example ZCTA seasonal resident ratio
  (1,307 10,439) / 10,439 1.125

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Now ready to apply seasonal resident ratio
developed at ZCTA(s) level to service area
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Calculation of Census Era Seasonal Households

• Seasonal households
• ((seasonal resident ratio 1) x Census
  population in households) / seasonal persons per
  household
• Example service area seasonal households
  ((1.125 1) x 5,460) / 1.95 351

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Calculation of Census Era Seasonal to Total
Household Ratio

• Seasonal to total household ratio (seasonal
  households) / (seasonal Census households)
• Example service area season to total households
  
• 351 / (351 2,289) 0.1328

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Current Year Seasonal Population

• Current year residential units served 1,479
• Seasonal population residential units served x
  seasonal / total household ratio x 1.95
• Example service area seasonal population
  1,479 x 0.1328 x 1.95 383

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Current Year Service Area Permanent Population

• Permanent population (1 seasonal/total
  household ratio) x residential units served x
  Census persons per household
• Example service area permanent population (1
  0.1328) x 1,479 x 2.385 3,059

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Seasonal Resident Adjustment Factor to
Functionalize Seasonal Population

• For Coastal Beach Destination Counties
• ((0.442 x 132) ((1 - 0.442) x (132 69.3))) /
  132 .707
• For All Other Counties
• ((0.567 x 132) ((1 0.567) x (132 69.3))) /
  132 .773
• 0.442 and 0.567 portion of year seasonal
  residents are here
• 132 gpcd the District-wide average per capita
  1996-2001
• 69.3 gpcd AWWARF study value for indoor
  residential use

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Functionalize Current Year Service Area Population

• Functional seasonal population seasonal
  population x seasonal resident adjustment factor
• Assume non-beach destination county
• Example functional service area seasonal
  population 383 x 0.773 296

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Calculate Current Year Service Area Group
Quarters Population

• Group quarters population (Census service area
  group quarters population / Census service area
  total housing units) x current year residential
  units served
• Example service area group quarters population
  (183 / 2,742) x 1,479 99
• Can do survey to estimate current year group
  quarters population

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Calculate Current Year Service Area Required
Population

• Required population permanent population
  functional seasonal population group quarters
  population
• Example service area required population
• 3,059 296 99 3,454

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Features of New Methodology Optional Tourist
Population

• Provides a standardized, public lodging- based,
  methodology for estimating a functional tourist
  population based on average occupancy rates,
  guests per room, and number of rooms served
• Allows for optional in-home tourist survey as
  part of a seasonal resident survey or a separate
  survey

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Current Year Service Area Tourist Population

• Tourist population total lodging rooms for
  lodging facilities served x average occupancy
  rate x average persons per room
• District has recent GIS layer of lodging
  facilities and rooms select served lodging
  facilities
• District has recent occupancy rates
• District has default average persons per room
• May do survey for lodging data in-home tourists

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Calculation of Current Year Service Area Tourist
Population

• Service area tourist population rooms served x
  average occupancy rate x average persons per room
• Example service area tourist population
  48 x 0.605 x 2.3 67

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Features of New Methodology Optional Net
Commuter Population

• Net change in service area population during the
  regular work week caused workers entering or
  leaving the service area to work
• Select Census tract(s) to represent current
  service area
• Create ratio of Census era tract level net
  commuters (calculated by District) to tract level
  housing units
• Net commuter ratio is applied to current year
  residential units
• Net commuter population multiplied by 8/24
  (0.333) and 5/7 (0.714) to functionalize

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Calculation of Current Year Service Area Net
Commuter Population

• Example service area net commuter population is
  zero so would not calculate
• Assume Census net commuter population is 40
• Census housing units in tract is 1,639
• Example service area current year service area
  net commuter population
  (40 / 1,639) x 1,479 x .33 x .714 9

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Compliance Assistance

• District willing and able to provide all
  necessary data to all utilities except lodging
  units served (but have layer)
• District identifies data from appropriate Census
  blocks, ZCTAs and tracts
• Data will be available online in the Utility
  Demographics page.
• Data is based on service area map on
  PS_SERVICEAREA layer as of the time of
  calculation
• Very important Help us keep your PSSA map
  current by submitting updates

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Spreadsheet includes basic Census 2000 statistics
for PSSA, seasonal resident estimates, and....
General Formulae provided to assist in
understanding how calculated numbers were
generated
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...net commuters.
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Analysis of Change in Population

• 44 utility service area populations from 2002
  Public Supply Survey
• Housing units served corrected where obviously
  incorrect
• Average percent change 1.51
• Median percent change 0.45

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Per Capita Compliance

• Typically addressed at time of renewal
• Must develop conservation plan to come into
  compliance
• Be proactive

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Residential Water Use Reporting

• Report annually on public supply survey
• Number of single-family units served and total
  water use
• Number of multi-family residential units served
  and total water use
• Number of mobile home units served and total
  water use unless included in SFR or MFR

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Reclaimed Stormwater Reporting

• Report annually on public supply survey
• Total reclaimed water or stormwater provided by
  permittee on both a total average annual daily or
  monthly basis
• For all individual customer reuse connections
  with line size 4 or greater account name and
  address, location of connection, line size,
  quantities if metered

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Questions and Discussion
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Next Steps

• Report input to Governing Board at June 26th
  meeting
• Based on input, Board could decide to hold
  additional hearings or publish notice of proposed
  rulemaking when rule language ready
• Once published, would have 21 days from date of
  publication to comment