Abstract
The U.S. Geological Survey (USGS) Wisconsin Water Science Center is
responsible for presenting data collected or estimated for water withdrawals
and diversions every 5 years to the National Water-Use Information Program
(NWUIP). This program serves many purposes such as quantifying how much,
where, and for what purpose water is used; tracking and documenting
water-use trends and changes; and providing these data to other agencies
to support hydrologic projects. In 2005, data at both the county and
subbasin levels were compiled into the USGS national water-use database
system; these data are published in a statewide summary report and a
national circular. This publication, Water Use in Wisconsin, 2005, presents
the water-use estimates for 2005; this publication also describes how
these water-use data were determined (including assumptions used), limitations
of using these data, and trends in water-use data presented to the NWUIP.
Estimates of water use in Wisconsin indicate that about 8,608 million
gallons per day (Mgal/d) were withdrawn during 2005. Of this amount,
about 7,622 Mgal/d (89 percent) were from surface-water sources and
about 986 Mgal/d (11 percent) were from ground-water sources. Surface
water used for cooling at thermoelectric-power plants constituted the
largest portion of daily use at 6,898 Mgal/d. Water provided by public-supply
water utilities is the second largest use of water and totaled 552 Mgal/d.
Public supply served approximately 71 percent of the estimated 2005
Wisconsin population of 5.54 million people; two counties—Milwaukee
and Dane—accounted for more than one-third of the public-supply withdrawal.
Industrial and irrigation were the next major water uses at 471 and
402 Mgal/d, respectively. Non-irrigational agricultural (livestock and
aquaculture) accounted for approximately 155 Mgal/d and is similar to
the combined withdrawal for the remaining water-use categories of domestic,
commercial, and mining (131 Mgal/d).
Data on water use in Wisconsin by source of water and category of use
have been compiled at 5-year intervals since 1950. During the past 55
years (1950–2005), water withdrawn to meet demands for public supply
and self-supplied irrigation, industrial, commercial, domestic, and
livestock increased 333 percent (1,117 Mgal/d). The greatest increases
were for public supply, industrial, and irrigation, and are reflected
in the increasing total per-capita water-use values. In recent (2000
and 2005) water-use estimation years, both public-supply and self-supplied
domestic per-capita-use values have been declining. This can be attributed,
at least in part, to a reduction in industrial-water deliveries, increased
water-efficiency standards, and the implementation of leak-detection
programs and water-conservation practices. However, when making comparisons
to evaluate trends among other Wisconsin water-use estimation years,
it is important to be aware of changes that may have occurred in estimation
methods or objectives that create differences. Some changes that have
occurred are the availability of data and information about water use,
changes in data sources and estimation methods, and the inclusion and
exclusion of certain water-use categories. These differences may have
an effect on apparent trends and make comparing trends difficult.