Use and Effectiveness of Municipal Water Restrictions During Drought in Colorado Bobbie Klein and Do

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Use and Effectiveness of Municipal Water
Restrictions During Drought in ColoradoBobbie
Klein and Doug Kenney
Natural Resources Law Center
Western Water Assessment
2002 Drought the Context
Results
Study Methodology
This table summarizes the various watering
restrictions and the period in which they were
effective. The most typical was the
circle-square-diamond schedule that permitted
watering every third day. The next most common
was the twice weekly schedule. One city was
forced to limit outdoor watering to once a week.
Some cities also limited the time of day and the
number of hours each day that watering was
permitted. Additional restrictions are noted.
The Western Water Assessment launched this study
to answer these questions How did Colorado
Front Range cities respond to the 2002 drought?
Were these responses effective? If so, by how
much?
The winter and spring of 2002 were abnormally dry
in Colorado. In the South Platte Basin snowpack
was never more than 55 of average. Snowmelt
provides a substantial portion of the municipal
water supply in Colorados Front Range.
We selected eight large and small municipal water
providers in the area around Denver extending
north to Ft. Collins. Their estimated 2002
populations are shown in this table.
Our study focused on outdoor water restrictions
since outdoor use accounts for over half of all
residential use in Colorado. We collected daily
water use data from each provider, as well as
daily precipitation and maximum temperature data,
for the period May 1 August 31. We compared
water use in 2002 to use during the same period
in 2000 and 2001 for both voluntary and mandatory
restriction periods and for the entire study
period.
Reservoir storage, which is vital to the Front
Range water supply, quickly fell to very low
levels. Some reservoirs were virtually empty by
the end of the summer.
This table summarizes the percent savings in
water use. In general, savings during mandatory
restrictions were greater than during voluntary
restrictions, and cities allowing watering only
one or two days per week saved more than cities
allowing watering every third day.
In this table we show water savings in terms of
acre feet. One acre foot equals 325,851 gallons
and is roughly the amount needed to satisfy the
needs of a Colorado family of 4 for one year.
Union Reservoir in Longmont holds approximately
12,000 acre feet.
We measured water use three ways Overall
deliveries in 2002 versus 2000/01 Per capita
use in 2002 versus 2000/01 Expected per capita
use in 2002 versus actual per capita use in 2002.
Expected per capita use is our estimate of what
per capita use would have been in 2002 absent
restrictions--based on the assumption that
demands that year would be higher than in normal
years due to the hot, dry conditions. To
estimate expected per capita consumption maximum
daily temperature and precipitation were used as
predictors in a multiple regression equation.
By early May, the entire state was a moderate to
extreme drought, though the South Platte basin
had avoided the worst of it. This would quickly
change as the weeks wore on.