Managing Semi-Arid Watersheds: History of the Arizona Watershed Program
The main focus of the Arizona Watershed Program (AWP), a joint initiative
of the Arizona Water Resources Committee and the State Land Department,
was to work with the USDA Forest Service, their cooperators, and others
to obtain and extrapolate research findings on water yield improvement
to large-scale watershed management practices designed to increase water
yields by manipulating vegetative cover.
Need for Water
One situation that conditioned and circumscribed people's behavior throughout
Arizona and the Southwestern United States was the perennial shortage
of water. The expected but variable supplies of surface water have long
since been appropriated. Electricity and electric pumps enabled access
to previously unavailable groundwater sources, while the favorable climate
resulted in an increase in agriculture and urbanization.
As a consequence, nearly all of the increased water supplied to this
rapidly growing area is pumped from underground basins. This increase
in pumping has caused a steady decline in regional water tables, which
has affected local economies. Many acres that formerly supported agriculture
have been abandoned, converted to housing developments, or switched to
an alternate source of water, such as the Central Arizona Project (CAP)
water that became available in the late 1980s.
However, the water situation, especially in the heavily populated areas,
has had little affect on people's use of water, except for the farmer.
Within any user group (household, municipal, commercial, industrial, or
agriculture), the willingness to pay for water varies significantly depending
on the benefits obtained from its use.
Water uses by various crops and user groups
For example, as the price of water increases, the quantity demanded by
various users changes because of differences in their ability to purchase
water. Household users have the highest willingness to pay and one of
the lowest quantities demanded (about 2 to 3 acre-ft/acre/yr assuming
4 families per acre). On the other hand, the willingness of farmers to
pay is far less than any other user. However, their crops require much
more water (5 and 6 acre-ft/acre/yr to grow cotton and alfalfa, respectively).
To put this in perspective, the native desert around Phoenix uses about
When the cost of water sufficiently reduces the farmer's income, he is
forced to stop farming and either abandons or sells his land to a developer
who provides what many homeowners desire: artificial lakes, golf courses,
pools, and green lawns. Conversion of water previously used for agriculture
(5 or 6 times that used by a household), therefore, has the potential
to sustain growth of municipalities and industry for some years into the
Barring conversion of saline water, additional importation of outside
water, advancements in rainmaking, and rigorous conservation measures,
regional residents must rely on the variable surface and diminishing groundwater
supplies. In response to this situation, the initial direction of research
in the arid and semi-arid Southwest focused on investigating the potentials
for increasing water yields from forests, woodlands, and shrublands of
the region through vegetative manipulations.
Arizona Watershed Program
The University of Arizona was commissioned in 1955 to investigate the
potential for increasing water yield from the state's forest and rangelands.
Numerous watersheds were instrumented with various climatic and hydrologic
measuring equipment by the USDA Forest Service, and its cooperators, in
the late 1950s and throughout the 1960s to study the effects of vegetative
clearings, thinnings, and conversions on water yields under controlled,
These watersheds formed a research network, called the Arizona Watershed
Program, for public agencies and private groups interested in obtaining
more water for future economic growth while maintaining the state's watersheds
in good condition. This collaborative program was the focus of watershed
research in Arizona through the 1960s, 1970s, and into the early 1980s.
Barr, G.W. 1956. Recovering rainfall: More water for irrigation,
Part I. Arizona Watershed Program. Cooperating: Arizona State Land
Department, Water Division of the Salt River Users' Association, University
of Arizona. 33 p.
Fox, K.M., P.F. Ffolliott, M.B. Baker, Jr., and L.F. DeBano. 2000. More water for Arizona: A history of the Arizona Watershed Program
and the Arizona Water Resources Committee. Primer Publishers, Phoenix,
Arizona. 118 pp.
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