WSP06374

• File Number: 8056
• Description: Drought Preparedness
• State: CO
• Basin: Statewide
• Date: 6/1/1988
• Author: Washington State DSH
• Title: Guidelines for the Preparation of Water Shortage Response Plans
• Water Supply Pro - Doc Type: Report/Study

Based upon a utility's cu=ent collSUl1pt.ion infonnation (Worksheet 1) and
any projected growth or dl:y weather that may cx::cur (Worksheet 2), a one-
year water demand forecast can be made. To project water demand for the
next twelve months, or for the projected duration of a water shortage,
s:i.rrply add current consumption, projected growth demand, and projected
"drought factor", if appropriate. '!his is vour proiected del1land.

~RKBHEET 3
Water IleInand PrOjections

B. supplv Analvsis

Once utilities have an estilllate of their expected water del1land over a given
time periOd, the focus can shift to an evaluation of existing sources and
their limitations. Knowing how much supply is available allows utilities
to compare supply and demand and to project, not only a shortage, but the
maonitude of the shortage they are likely to have. Knowing the magnitude
of a potential shortage would give utilities more precise infonnation upon
which to base nanagement decisions.

Unfortunately, quantifying or estilllating available supply is a much more
difficult task than quantifying or estilllating consumption. As a result,
utilities may have only a vague idea of how much water is safely or
optilllally available for withdrawal from a source. Although prediction of
the magnitude of a potential water supply deficit is desirable, it is not
always possible given the cost and effort of obtaining such infonnation and
cu=ent knowledge of aquifer and basin capacities. Therefore, the inportant
thing to detemine is whether a utility believes there is a trend toward
decreasing supplies in the near future.

1.... Water SooPl v Factors

Natural r~ce agencies and larger water utilities use various factors
as indicators of water supply. For surface water, some of these supply
indicators are:

o river and stream inflow projections;
o reservoir and lake levels;
o intake or water extraction levels;
o snowpack; and
o evaporation and seepage rates.

For ground water, some of these supply indicators are:

o static water levels;
o pumping water levels;
o ground water table elevations;
o aquifer characteristics;
o well depth, construction, and pump limitations; and

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