Demand Forecast Work Plan
Water Suppliers’ Forum
Steering Committee Proposal
Working Draft Version 3.4
Objective:
The Water Suppliers’ Forum (Forum) will develop an updated municipal water
supply demand forecast for King, Pierce, and Snohomish County. This work will
result in an updated Municipal Water Supply Demand Forecast for each of the
three counties and is expected to meet the objectives of the King County
Planning process. The Forum is committed to provide a creditable and
transparent demand forecast and meaningful participation to interested
stakeholders (See Stakeholder Input and Process Transparency below). The
goal is to develop the best available information on future municipal water
demands to assist in making more informed decisions on future water supplies.
Approach:
The municipal water supply Demand forecast will be based on Growth
Management Act compliant data provided by the Puget Sound Regional Council
(PSRC). The data includes both historic demographic data (single and multifamily households, employment, and population) at the Transportation Analysis
Zone (TAZ) level as well as projected future forecasts to be used for planning by
all local governments. The PSRC forecasts account for land uses as established
by local land use authorities and has been “approved” by a local and state
government review process.
Water use factors will be based on historic water consumption of each water
utility which reflects the effects of land-use, historic conservation and community
values. The effects of future water efficiency and conservation programs will be
discussed, and may either be embedded in water use factors, or included in
conservation scenarios that may be part of the demand forecasts.
To the extent that the Forum surveys water utilities for use data, the Forum will
request data from utilities on any significant known non-potable water users or
self-supplied uses in their service area and will include reported information in
any summary report prepared. It should be noted that water utilities generally do
not have information on that portion of water that they provide that is used for
non-potable water uses, consequently any data reported should not be
considered complete or accurate. Additional information on self-supplied users
and uses will be requested from Ecology.
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Stakeholder Input and Process Transparency:
It is the intent of the Forum to provide any interested stakeholders the opportunity
to participate in the development of the Municipal Water Supply Demand
Forecast. To achieve process transparency and opportunity for meaningful
participation and input, the Water Suppliers’ Forum will establish a municipal
water supply Demand Forecasting Review and Oversight Committee
(Committee). The Committee will provide both technical review and oversight
functions.
The Committee will be made up of interested persons: selfselected, stakeholder selected, or selected by or through other planning
processes, such as planning process underway in King County.
The Committee will be formed before the scope of work for the demand forecast
is finalized or any technical consultant is selected. The Forum is looking to the
Committee to provide advice on process issues, as well as on technical and
policy issues that arise throughout the development of the Municipal Water
Demand Forecast.
It is the intent that the Committee will seek to reach substantial agreement on
elements that are important to the development of the Municipal Water Demand
Forecast. Such elements may include conservation and efficiency assumptions,
population expectations, including alternatives to the PSRC forecasts. It is
anticipated that in some cases a variety of scenarios may be developed to
provide a range of forecast. The Committee will have the opportunity to review
and suggest alternatives to scenarios that are to be used. All data used and
materials produced will be available to members of the Committee.
Formation of the Committee will be an initial step in the work to assure input on
the criteria for the work, the consultant selection process and initial direction of
the work. It is anticipated that the Committee will establish a regular meeting
schedule to monitor work progress and work product development and provide
advice on the project to the Forum. In addition, the Committee may choose to
have additional meetings and/or other means to allow an appropriate level of
review and comment on the development of the Demand Forecast.
The Water Suppliers’ Forum will support and facilitate the coordination and work
of the Committee. The Forum may retain specialized facilitation services as
necessary to complete this work.
Background:
A computational model similar to that used to develop the municipal water supply
demand forecast in the Outlook will be used. Seattle Public Utilities has built
upon the approach used to develop the original demand forecasts in the Outlook
and developed a model that is available for the Forum’s project. The model uses
population and household data from the Puget Sound Regional Council. The
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data includes a detailed distribution to Transportation Analysis Zones (TAZ).
Seattle’s model then assigns the TAZ data to water utility service areas using a
graphic approach (with some enhanced sub-routines). Water use factors can be
developed from historic data.
Seattle has included a number of enhancements that may or may not be of
interest in a regional forecast. As a result the demand forecast may include
“adjustments” that would allow the model to develop a “suite” of demand
projections.
Moving Forward:
A new set of regional forecasts are to be available by March 2006 from the Puget
Sound Regional Council. That date would constitute an early start time for the
beginning actual work on the update.
If the Water Suppliers Forum agrees to undertake this effort then the process
would begin with identification and convening of the Demand Forecasting Review
and Oversight Committee (Committee). It is estimated that it would take a
minimum of 9 months (and likely longer) to prepare the Demand Forecast with
coordination and review with local utilities and with meaningful participation of
Committee.
Demand Forecast Features:
The municipal water supply demand forecast will include the following features:

Forecast periods – 6 and 20 years (or as close as possible from available
data) and a long-range forecast estimate of 50 years. Forecast periods of
6 and 20 years are selected to match Department of Health Water System
Planning Requirements.

A discussion of seasonal variations in water use and estimates of
appropriate seasonal water use factors for a regional demand forecast.

A clear narrative that describes the three county municipal water supply
demand forecast (Regional Demand Forecast) including its development
and uses and the differences between regional forecasts and utility
specific water demand forecasts that are done as part of the water system
planning process. The narrative should also provide an overview of
changes in regional use that occurred in the past 30 years to provide a
basic understanding of the dynamic nature of water use by municipal
water customers.
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
A discussion of the effects of weather and climate change on municipal
water demand will be included. Historically water suppliers have
experienced significant changes in year to year water use based on
current weather patterns (damp spring, cool summer, hot summer, etc.).
The work will include identification of any important metrics associated
with weather and the associated effects on demand.

A discussion of the effects of regional economic conditions and household
income on municipal water demand will be included. The objective would
be to develop an estimate of how water demand may change from these
factors. The result could be a “range of effects” that could be used to
modify base demand projections.

The Municipal Demand Forecast is being prepared to assess the future
water needs for municipal water suppliers and other domestic water users.
It will not include agricultural water use, industrial water use or irrigation
water uses not provided by municipal water suppliers. (The demand
forecast will estimate future water needs of households not currently
served by water suppliers, both inside and outside water service areas,
but will not include extraordinary irrigation uses beyond those normally
provided by public water systems.)

Water utilities do not maintain information on self supplied water users
inside or outside their water service areas. Consequently any
identification of self supplied users is beyond the scope of a Municipal
Water Supply Demand Forecast, and will be separately identified.
The Demand Forecast should include the following:

Conservation and Effects of Future Water Efficiency and Conservation The work will include a reevaluation of how to best include the historic
affects of water conservation programs and recommendations of how to
include projected future water conservation effects on the municipal water
demand forecast. The intent is to have the Committee play an important
role in deciding how conservation and future conservation be handled in
the demand forecast. Initially it seems it might be done through a series of
conservation levels that result in different demand scenarios, but there are
likely other useful approaches.
Water Suppliers’ Forum Role:
The Municipal Water Supply Demand Forecast is a Water Suppliers’ Forum work
effort that will be funded and managed by the Water Suppliers’ Forum.
Consequently the Water Suppliers’ Forum will establish the schedule and will
have final authority on approval on the scope of work, the work product and other
issues to assure that the project is conducted consistently with the availability of
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necessary data, Water Suppliers’ Forum ability to manage the work, legal
constraints such as consultant selection requirements, and consultant schedules,
accepted professional practice and Water Suppliers’ Forum cash flow.
The Water Suppliers’ Forum will provide quarterly reports, as requested, on the
progress of the Municipal Water Supply Demand Forecast to interested groups,
including those in the King County Planning Process.
Supply Analysis:
The Municipal Water Supply Demand Forecast will end with identification of a
suite of future demand scenarios and will not include identification and evaluation
of municipal water supply alternatives which will be a separate work element.
Initial Thoughts on Demand Forecast Budget:
The budget necessary to do the work will be finalized after defining the Scope of
Work and selecting the Project Consultant. The Water Suppliers’ Forum Steering
Committee has prepared the following as a discussion budget to assist the
Forum in defining the work and the level of detail. Work done by Seattle Public
Utilities developing the model, and preparing demand forecasts for the Seattle
Water Supply System was used to prepare this initial discussion budget. Bruce
Flory indicated that the development time to prepare the model and do the initial
forecasts for Seattle required about 4 months of Bruce’s time and about one
month of GIS time. The advantage that Seattle had in this process is that they
did not have to depend on others (except PSRC) and it was a priority so they had
access to decision makers when needed. The Forum would not have that luxury
and would need to coordinate with utilities within the region and the Committee,
consequently it will take longer.
In considering what this effort might cost I have developed the following:

Demand Forecasting Review and Oversight Committee facilitation: Labor
allowance $45,000; expenses allowance $5000.
Total $ 50,000

Demand Forecasting, Preparation of Alternative Scenarios, and
Production of a Demand Forecasting Report: Labor allowance $175,000;
expense allowance $25,000.
Total $200,000

Forum Project Management: Labor allowance $35,000; expense
allowance $2000.
Total $37,000
Total $287,000
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