Plenty of Water?
JC Huntington, May 12, 2001


Because it is possible for a few individuals to make huge amounts of money by importing people to live in large, golf-oriented developments, we will be told that experts have determined that there is "plenty of water" to sustain several large, golf-oriented communities in the Oracle Junction area.

Although Arizona Water law makes it appear as though there is sufficient water, the reality is quite different.  In reality, groundwater in our active management area is being depleted much faster than it is being replaced. 

The regional aquifer that supplies water for Oracle is one of the few remaining aquifers in the Tucson AMA that is not suffering a severe overdraft.  However, if proposed development projects in the area are allowed to be built, this situation will change and the regional aquifer will be depleted just as the other aquifers in the Tucson AMA are currently being depleted.

The Tucson Active Management Area

In 1980, when it was finally recognized that unrelenting groundwater pumping was sucking aquifers dry, the Arizona Legislature passed the Groundwater Management Act. 

Areas that needed special attention were designated as Active Management Areas (AMA's). The Department of Water Resources (ADWR) was established and given legal tools to manage groundwater use in the AMA's. 

The figure below shows the Tucson Active Management Area and the other AMA's. 

The area around Oracle Junction is shown in the inset, with the aquifer represented by a light blue color.  The dashed line in the inset shows the boundary of the Tucson AMA. 

Source: ADWR and Montgomery and Associates 
Mark Cross, a hydrologist with Montgomery & Associates described the portion of the aquifer north of Oracle Junction as "pristine" -- in other words, the regional aquifer is relatively undefiled (at least as of now). 

The unsullied nature of the regional aquifer can be seen in the above image.  Note that while the southern region of the aquifer is coated with houses and golf courses, the portion of the aquifer north of Pinal/Pima line is relatively clear (except, of course, for the decades old Page-Trowbridge radioactive/toxic waste landfill).

A Very Large Overdraft

In 1995, 301,881 acre feet of groundwater was withdrawn from the Tucson AMA and only 60,800 acre feet of water was recharged into it. 

This is an overdraft of 241,081 acre feet (78,556,484,931 gallons) of water. 

Overdrafts of this magnitude continue to this day despite the use of CAP water. The Tucson area's overdraft on ground-water in 2000 was 169,500 acre-feet (55,231,744,500 gallons). 

Thus, the aquifer north of Oracle Junction may be the last remaining intact aquifer in the Tucson AMA.

Oro Valley affords and example of the more normal aquifer within the Tucson AMA.  While the water level of the aquifer north of Oracle Junction is stable, the aquifer in Oro Valley area is being depleted to the point that the water level is dropping at a rate of 7 feet per year1.

The effect of the overdraft on the water supply in Oro Valley is shown in the chart below2.

The top line of the chart shows the amount of rainfall for the years 1971 to 1997. 

The bottom line shows the decline in the water level from 1971 to 2000. 

So, while rainfall is fairly constant, the amount of available groundwater is declining at a rather alarming rate. 

Development & Decline

A quick look at the map of the portion of the aquifer in the area of Oro Valley shows us that the portion of the aquifer suffering a dramatic decline in groundwater is coated  with houses and golf-courses. (This is not too surprising -- the more you use a limited resource, the faster it is used up).

An Insane Response

The sane response to the severe overdraft condition on the Tucson AMA would be to take steps to control it. 

The figure below shows the actual response to the severe overdraft problem.  The figure shows the proposed developments that will pump water from the one of the last unsullied aquifers in the Tucson AMA.  If these developments are allowed, a few years from now the decline in the water supply north of Oracle Junction will mimic that seen today in Oro Valley and Tucson.

In other words, the response to a severe depletion of groundwater in the Tucson AMA is to continue to cover the aquifer with more houses and golf-courses. 

A System of Aquifers

Groundwater in the aquifer north of Oracle Junction moves to the south and helps replenish the water supply for the communities below Oracle Junction.  Depleting water from the portion of the aquifer north of Oracle Junction will lower the water level and slow the movement of water to the south, exacerbating the overdraft problem in Catalina, Sun City Vistoso, Oro Valley and Northwest Tucson.

Arizona Water Law: A Word Game

The names used to describe Arizona Water law make it sound as though the law is addressing the problem of a declining water supply. 

For example:

  • Developers must obtain a Certificate of Assured Water Supply showing  that there is sufficient water to supply a new development for at least 100 years -- 
  • Safe yield is a rule governing water use in the Tucson AMA to assure that by the year 2025, no more groundwater is pumped than can be recharged either from natural sources (rain) or artificial sources (CAP, etc.).
  • However, when the details are looked at, it is seen that Arizona Water law only makes it appear as though the problem is being addressed -- it is a trick of words that is being played here.

    In a very real sense, the current situation is worse than having no law at all. If there were no law, people would not be mislead into believing the problem is actually being addressed.

    Certificate of Assured Water Supply

    Before a development is permitted to be built in the Tucson AMA, the developers must obtain a Certificate of Assured Water Supply.  Certificates of Assured Water Supply are issued by the ADWR, and is an assurance from the state that water is legally and physically available to the development for at least 100 years.

    While the name Certificate of Assured Water Supply sounds great, the key is understanding exactly how ADWR goes about assuring the water supply.

    According to the law, physical availability simply means that the developer must show that the water used by the proposed development along with existing developments will not lower the water level more than 1000 feet below land surface, or the bottom of the aquifer, whichever comes first within a 100 years.

    So, if the hydrologists hired by the developers can show that the demands of the developments will only lower the water level by 9.99 feet per year, then in 100 years the water level will have dropped only 999 feet.  Since 999 is less than 1000, ADWR will declare that there is plenty of water available for the developments.  (Of course the wells for the developments would have to be punched at a location where the aquifer is at least 1000 feet deep).

    Unfortunately, because aquifers are shaped like saucers, the depth of the aquifer near the edge is much more shallow than the depth near the center. 

    The following figure below (from ADWR) shows the shape of the aquifer under Tucson and illustrates the "shallow bowl" shape of aquifers:

    Because of the saucer shape, wells on the margins of the aquifer will go dry before the wells near the deep part of the aquifer go dry, as illustrated below:
    By the way, the regional aquifer has the same saucer shape.  The deepest part of the regional aquifer is near Oracle Junction.

    It is a very, very good bet that the wells for SaddleBrooke Ranch and the South Village of Willow Springs will be located near Oracle junction for the same reason that the wells supplying Oracle are at Oracle Junction -- that is where the water is.

    The Myth of Safe Yield

    The goal of the Tucson AMA is to achieve safe yield by the year 2025 so that no more groundwater is pumped out of the aquifers in the Tucson AMA than can be naturally or artificially recharged.

    Like the Certificate of Assured Water Supply, the name "Safe yield" sounds good, but there is a little catch.  In the case of safe yield, the catch is that the law allows the "replacement" water to be put back anywhere in the Tucson AMA. 

    In the case of Willow Springs, SaddleBrooke Ranch, Eagle Crest and other proposed projects, the CAP water used to "replace" the water pumped from the aquifer north of Oracle Junction to feed the golf courses and residents in these new developments, will be recharged at the Avra Valley CAP Recharge Project.  The Avra Valley Recharge Project is some 40 miles down aquifer from the aquifer that supplied the groundwater.

    Since the Avra Valley Recharge Project is several hundred feet lower than the regional aquifer and since water doesn't flow uphill,  none of the CAP water used to "replace" water taken from the regional aquifer will ever make it to the regional aquifer. 

    In other words, the regional aquifer be legally depleted because another aquifer miles away will be recharged with the same amount of water pumped from the regional aquifer to supply the new residents and their golf courses with water. 

    So, while the water level in the aquifer north of Oracle Junction declines, a computer data base at ADWR will record that everything is ok because X acre-feet of water was recharged at Avra Valley to make up for groundwater pumped at Oracle Junction.

    The figure below is from the CAP web site ( and shows the location of the Avra Valley Recharge project.


    1: Conde, H.  Report on Oro Valley Water Table Decline. Oro Valley, AZ, 1999
    2: Personal communication from H. Conde

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