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Cultural Water Demand in the Southeastern Arizona Planning Area - Industrial Demand

Total cultural water demand for tribal, municipal, agricultural and industrial uses in the Southeastern Arizona Planning Area averaged approximately 515,100 AFA in the period from 2001-2005. The agricultural demand sector is by far the largest water demand sector with over 440,000 acre-feet of demand (see Figure 3.0-16).  This is primarily due to agricultural demand in 4 basins Willcox, Safford, Duncan Valley and Douglas, which account for 410,600 acre-feet, or 95% of the agricultural demand. About one-fifth of the agricultural demand is met with surface water. 

Figure 3.0-16 Southeastern Arizona Planning Area Average Annual

Cultural Water Demand by sector, 2001-2005

Cultural Water Demand

Industrial water demand in the planning area includes mining, electrical power generation, dairies and feedlots, and golf course irrigation served by a facility water system. This demand is summarized in Table 3.0-14 for selected years. Mining is the largest industrial user in the planning area, primarily due to activities in the Lower San Pedro and Morenci basins.

The Morenci Mine in the Morenci Basin is North America’s largest producer of copper and one of the largest open pit mines in the world. The mine property covers about 60,000 acres and includes five pits, three of which are currently in operation, and SX/EW (solution extraction/electrowinning) facilities.  Reportedly, almost all of the water used at Morenci is recycled, some of it many times (InfoMine, 2006).  Most of the water utilized by the mine and by the Morenci Water & Electric Company (a subsidiary of Phelps Dodge) is diverted from the Black River in the Salt River Basin and transported into the basin, or is from the Upper Eagle Creek Well Field. Water diverted from Gila River tributaries typically accounts for about 10% of the total (ADWR, 2005c).  Phelps Dodge has a 50-year lease agreement with the San Carlos Apache Tribe pursuant to the San Carlos Apache Tribe Water Rights Settlement Act of 1992, as amended in 1997, to lease up to 14,000 AFA of its allocation of CAP water by means of an exchange at the Black River Under the 1944 Horseshoe Exchange Agreement, Phelps Dodge also is entitled to diversions of up to 250,000 acre-feet from the Black River (ADWR, 2005c).  As of the beginning of 2009, Phelps Dodge had used almost 102,500 acre-feet of Horseshoe Reservoir credits (SRP, Personal Communication). Water from recovery wells installed in the mine area for dewatering purposes is also used at the mine, as is effluent from the Morenci Water & Electric Company.

In the Lower San Pedro Basin, the ASARCO Ray Complex includes a 250,000 ton/day open pit mine northwest of Kearny, a SX/EW operation and a smelter at Hayden.

Two large copper mines in the planning area are currently out of production. The BHP Billiton Base Metals in-situ copper leaching operations at San Manuel in the Lower San Pedro Basin closed in early 2002 and  underground mining at the site ceased in August 1999.  In February 2002, Pima County approved BHP’s request to redesignate some of its property for uses other than mining. (ADWR, 2006) 

The Phelps Dodge Copper Queen mine in the Upper San Pedro and Douglas Basins currently consists of a small dump leaching and precipitation operation at the Lavender pit  (Arizona Mining Association, 2006). Open pit mining started in 1917 and continued, with some interruptions, at the Sacramento pit and Lavender pit until 1974.  All active mining stopped in 1984. Considerable dewatering of the mine workings was necessary with long-term groundwater production of about 4,000 AFA (Southwest Ground-water Consultants, Inc., 2004). 

 

Table 3.0-14  Industrial Demand in the Southeastern

Arizona Planning Area

 
1991-1995
1996-2000
2001-2005
Type/Basin Water Use (acre-feet)
Mining Total
48,195
47,085
25,831
Cienega Creek
Groundwater
<300
<300
<300
Lower San Pedro
Groundwater
30,800
26,100
15,700
Morenci
Surface Water
2,425
2,105
1,141
Groundwater
13,700
17,800
8,100
Safford
Groundwater
650
500
370
Upper San Pedro
Groundwater
170
200
210
Willcox
Groundwater
300
230
160
Power Plant Total
6,000
5,200
5,700
Willcox
Groundwater
6,000
5,200
5,700
Golf Course Total
1,596
1,806
2,316
Duncan Valley
Groundwater
210
210
210
Lower San Pedro
Groundwater
211
211
211
Morenci
Groundwater
75
75
75
Safford
Groundwater
0
210
420
Upper San Pedro
Groundwater
1,100
1,100
1,400
Dairy/Feedlot Total
262
272
502
Duncan Valley
Groundwater
100
100
100
Upper San Pedro
Groundwater
42
42
42
Willcox
Groundwater
120
130
360
Other Total
290
290
290
Upper San Pedro
Groundwater
290
290
290
Total
56,343
54,653
34,639
Sources:  ADWR 2008d, USGS 2007a
Notes:  Volume <300 acre-feet assumed to be 150 acre-feet for computation purposes.

 

Copper Queen Mine

Copper Queen Mine, Douglas Basin

Phelps Dodge Corporation began full operation of a large open pit mining operation in the Safford Basin in 2008.  Located eight miles north of the town of Safford, the 3,400 acre Safford (Dos Pobres) operation includes two open pits, one heap leach pad, one process solution pond, one evaporation pond, a SX/EW process plant and other infrastructure and support facilities (InfoMine, 2008; ADEQ, 2006c).  Average annual groundwater demand by the mine is projected to be about 5,500 AFA (ADWR, 2006).

The only power plant in the planning area is the Arizona Electric Power Cooperative (AEPCO) Apache Station Generation Plant located in the Willcox Basin in Cochise, southwest of Willcox. The plant is a gas-fired combined cycle plant built in 1963 that generates 520 megawatts of electric energy for its cooperative members located throughout Arizona and California (AEPCO, 2006). Average annual demand during the period 2001-2005 was slightly lower than the average annual demand during the period 1991-1995 but annual demand can vary considerably, from a low of 4,100 acre-feet in 1996 to a high of 6,600 acre-feet in 1991.

There are seven industrial golf courses in the planning area, which are defined as those courses with their own facility water supply. They are shown in Table 3.0-11, along with municipally served golf courses, with estimated demand and source of water.

Three dairies and two feedlots have been identified in the planning area. There is a small, approximately 350 animal dairy north of Benson in the Upper San Pedro Basin (Cliff’s Dairy), a large dairy of about 5,400 animals near Kansas Settlement (Faria Dairy) in the Willcox Basin that began operation in 2004, and an approximately 855 animal dairy in the Duncan Basin (Lunt’s Dairy). Demand is about 42 acre-feet, 588 acre-feet and 120 acre-feet respectively.  There are also two feedlots in the Willcox Basin with a combined total of about 4,000 animals and a demand of about 130 acre-feet in 2005. Development of dairies and feedlots typically results in increased agricultural irrigation for feed.

The Apache Nitrogen Products facility is an ammonium nitrate manufacturing plant located south of Benson in the Upper San Pedro Basin.  The facility has made efforts to reduce its water consumption, and in 2005 used an estimated 289 acre-feet of groundwater, a reduction of about 250 acre-feet since 1991.

A number of sand and gravel facilities are located throughout the planning area. Some of these are identified on the cultural demand maps for each basin. However, not all are identified in the source data used for the maps. Water is used for aggregate washing, dust control, vehicle washing and equipment cooling. Typically, there is relatively little water consumed at these sites since most facilities recycle wash water. The Department estimated that a typical sand and gravel facility in the Upper San Pedro Basin uses less than 50 AFA (ADWR, 2005a).

 

 

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