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Lower Colorado River Cultural Water Demand - Agricultural Demand

Cultural water demand in the Lower Colorado River Planning Area, organized by water source and water demand sector, is shown in Table 7.0-10.  Total cultural water demand averaged approximately 2,899,700 AFA during the period from 2001-2005.   Almost 98% of this demand is by the agricultural sector with approximately 2,835,100 acre-feet of annual demand.  Agricultural demand occurs in all of the basins with the exception of Tiger Wash and Western Mexican Drainage basins.  About 66% of the agricultural demand is met by surface water of which all but 3% is Colorado River water.  Municipal demand averaged 50,900 AFA during the period 2001-2005.  Municipal demand is primarily met by Colorado River water and the municipal sector is the only sector that utilizes effluent.  Industrial demand, primarily related to dairies and feedlots, averaged 13,600 AFA during this period.  Tribal water demand is included in these totals.

Table 7.0-10 Lower Colorado River Planning Area average cultural water demand by sector (2001-2005)

Table 7.0-10

Agricultural Demand

The planning area contains one of the largest agricultural areas in Arizona and the nation.  Yuma County, which contains most of the agricultural lands in the planning area, is considered the nation’s winter vegetable capital. Crops grown here include head and leaf lettuce, romaine, broccoli, cauliflower, honeydew, cantaloupe, watermelon, cabbage, spring mix, celery, endive/escarole, and citrus including lemons, oranges, grapefruit, and tangerines. Many seed crops are also grown including broccoli, cauliflower, grasses, and onions.  Annual agricultural sales are reported to total over $1.3 billion.  In La Paz County, upland cotton is the largest crop, followed by Durum wheat, barley, corn for grain, and alfalfa.  Other crops include onions, honeydews, cantaloupe and watermelon. Annual agricultural sales are reported to total over $92 million in this county. (AZDA, 2005)

There are 13 irrigation districts in the planning area.  Their general location is shown in Figure 7.0-18 and described below.

Figure 7.0-18 Irrigation districts in the Lower Colorado River Planning Area

Figure 7.0-18

Irrigation water supply is primarily water diverted from the Colorado River.  As shown in Table 7.0-14, for the period 2001-2005, an average of about 1,108,000 AFA was diverted from the Colorado River for use in the Parker, Lower Gila and Yuma Basins. An additional 69,600 acre-feet was diverted via the Central Arizona Project for use in the Harquahala Basin.  Gila River water and effluent averaging 54,000 AFA was used in the Gila Bend Basin.  During this period an average of 935,700 acre-feet of water withdrawn from wells was used to irrigate lands in all basins with agricultural demand. 

Agricultural demand is greatest in the Yuma, Parker, Lower Gila, Gila Bend, McMullen Valley, and Harquahala basins.  As shown in Figure 7.0-20, agricultural demand has steadily increased over time in most of these basins.  Agricultural demand in each basin is described below. Included are findings from a USGS agricultural field survey conducted of the Butler Valley, Gila Bend, Harquahala, Lower Gila, McMullen Valley and Ranegras Plain basins in the summer of 2007, which are summarized in Table 7.0-15.

Butler Valley Basin

Agricultural demand in the Butler Valley Basin averaged 9,700 AFA during 2001-2005.  Demand has more than doubled compared to the 1971-1990 time period (Table 7.1-8). Agricultural lands are located in a contiguous area in the southwest part of the basin and groundwater is the only water supply. The USGS and found 1,352 acres of irrigated alfalfa/hay, all center pivot irrigated, in 2007. (USGS, 2009)

Gila Bend Basin

Irrigation in the Gila Bend Basin is located primarily along the Gila River valley and south of the Gila River in the western part of the basin.  Agricultural demand averaged  343,000 AFA during 2001-2005, of which 289,000 acre-feet was groundwater and 54,000 acre-feet was a mixture of Gila River surface water, agricultural drainage and effluent discharged upstream in the Phoenix AMA.  Gila Bend Basin agricultural demand was 12% of the total planning area agricultural demand.  Agricultural demand has increased steadily from an annual average of 278,000 acre-feet during the 1991-1995 time period (see Table 7.2-8).

Surface water/effluent supplies are used in the northern part of the basin where they are diverted at Gillespie Dam through the Gila Bend Canal and Enterprise Canal. Prior to 1993, when Gillespie Dam was breached during a flood, more surface water was diverted.  Surface water has been a less reliable supply than groundwater due to upstream dams and diversions and the unpredictability of flow even under pre-development conditions.   As shown on Table 7.2-8, the proportion of groundwater used has increased since the 1990s. Investigations by the USGS found about 43,400 acres under irrigation and all acreage was flood irrigated.  The predominant cropped acreage at that time was alfalfa/hay (76%), followed by sorghum (8%), wheat (7%) and smaller amounts of cotton, corn, jojoba, grasses and nursery plants. (USGS, 2009)

Table 7.0-14 Agricultural water demand in the Lower Colorado River Planning Area

Table 7.0-14

Figure 7.0-19

Figure 7.0-19 Irrigation Water Supply for the Lower Colorado River Planning Area, 2001-2005 (acre-feet)

Harquahala Basin

The number of irrigation acres allowed in the Harquahala Basin is limited due to the basin’s designation as an irrigation non-expansion area, or INA. In an INA farmers must report agricultural water pumpage and use on an annual basis to the Department.  Demand averaged 106,100 AFA, during 2001-2005, representing 4% of the agricultural demand in the planning area (Table 7.3-8).  Non-contract CAP water began to be used in 1984 by the Harquahala Valley Irrigation District (HVID), replacing groundwater pumpage as the primary water supply in the basin.  Under the Department’s Recharge Program, HVID is a permitted groundwater savings facility. 

HVID lands are the most extensive in the basin, covering a large area in the southeast portion.  All irrigation canals and laterals are concrete-lined (ADWR, 1998).  Other irrigated areas exist near Centennial and south of the Buckeye-Salome Road in the northwest part of the basin.  The USGS found 25,950 acres under irrigation in the basin in 2007.  At that time, about 33% of the cropped acreage was alfalfa/hay, 25% cotton, 14% wheat,13% melons and lesser amounts of corn, sorghum, grasses, oats and nursery trees. About 86% of the lands were found to be flood irrigated and 13% were drip irrigated. (USGS, 2009)

Figure 7.0-20 Agricultural Demand in Selected Basins in the Lower Colorado River Planning Area 1991-2005 (in acre-feet)

Figure 7.0-20

Lower Gila Basin

The Lower Gila Basin contained 22% of the agricultural demand in the planning area during the 2001-2005 time period. Demand within the basin averaged between 619,000 acre-feet during 1991-1995 to a high of 652,000 acre-feet from 1996-2000. Demand declined during 2001-2005 to an average of 629,000 AFA. Colorado River water (surface water) comprises about 60% of the water supply (Table 7.4-8).

The principal farming area is the Wellton-Mohawk Irrigation and Drainage District (WMIDD), whose location generally follows the Gila River Valley west of Dateland and extends into the Yuma Basin (see Figure 7.0-18).  Other irrigated areas are located north and west of Dateland, north of Hyder, near Agua Caliente (south of Hyder) and in the Dendora Valley near the eastern basin boundary.  Crop type and estimated irrigated acres in the WMIDD are shown in Table 7.0-15.

Principal crops grown were vegetables, alfalfa/hay, wheat, cotton, grasses (bermuda) and melon.  A significant amount of double cropping occurs in the district (WMIDD, 2004).  The irrigation method for each crop type was not available but flood irrigation is the primary irrigation method for most crops, with a few center pivots. Vegetables are irrigated with a combination of sprinkler (for seed germination) and flooding and melons are most likely irrigated with drip irrigation (personal communication, S. Tadayon, 2009).

Table 7.0-15 Agricultural acreage, crop type and irrigation type in selected basins in 2007

Table 7.0-15

The USGS field investigation of non-district lands in the summer of 2007 found much less land being irrigated north of Hyder than suggested by Figure 7.4-10.  The USGS found 20,750 acres being irrigated on non-district lands.  Principal cropped acreage observed was alfalfa/hay (39%), jojoba (13%), vegetables (9%), cotton (8%) and sorghum (6%). Citrus comprised 5% of the “other category” with lesser amounts of date/palm trees and oats.  Irrigation methods vary in this area with 15% of the acreage flood irrigated, 17% sprinkler, 13% drip and 13% center pivot (primarily north of Dateland). The irrigation method was unknown on 42% of the acreage. (USGS, 2009)

Reclamation’s Gila Project delivers Colorado River water to two divisions in the planning area - the Wellton-Mohawk Division and the Yuma Mesa Division.  The WMIDD was created in 1951 to provide a legal entity that could contract with the United States to repay the cost of the Gila Project and to operate and maintain project facilities.  Lands in the area have been cultivated for many centuries.  During the late 19th century, diversion structures and canals were constructed to expand agricultural lands, but periodic floods and construction of upstream reservoirs led to abandonment of the surface water system and conversion to groundwater wells.  However, by the early 1930s, increasing salt concentrations in groundwater and falling groundwater levels made successful farming in the area difficult and many farms were abandoned.  Area farmers approached Reclamation for delivery of Colorado River water and the project was constructed during the late 1940s and early 1950s. (WMIDD, 2004)

Agriculture in the Welton Mohawk

Agriculture in the Wellton-Mohawk IDD

Water for the District is diverted at Imperial Dam into the Gila Canal, a joint-use facility shared by five Yuma Basin irrigation districts (WMIDD, 2004).  The WMIDD Colorado River entitlement is diverted into the 18.5 mile long Wellton-Mohawk Canal and to its major branches, the Wellton Canal (19.9 miles long) and the Mohawk Canal (46.8 miles long).  The 13-mile long Dome Canal branches off the Wellton-Mohawk Canal west of the major branches and serves the western part of the District.  There are 13 small pumping plants and 227 laterals in the WMIDD.  (USBOR, 2007f)  Facilities include 378 miles of main canals, laterals and return flow channels, three major pumping plants, drainage wells and groundwater level observation wells.  All canals and laterals are concrete-lined except for eight miles of the main canal west of the first pumping plant.  There are also hundreds of domestic turnouts along the system (WMIDD, 2004).

The WMIDD has a Colorado River Priority 3 right with a current allowable consumptive use of 278,000 AFA, but diversions are significantly higher.  Diversions to the District averaged 408,258 AFA during the 2001-2005 time period.  Water pumped from drainage wells and returned to the Colorado River is deemed “return flow” that is subtracted from the District’s diversions to derive its consumptive use.

Long-term irrigation with Colorado River water combined with naturally elevated salt concentrations in groundwater and soil require that salts be leached from the soil by irrigating in excess of the crop consumptive use and removal of excess groundwater to prevent waterlogging.  In addition, occasional flooding on the Gila River raises groundwater levels.  The District operates 90 drainage wells spaced about a mile apart with an average depth of 100 feet to control rising groundwater levels, keeping water below the root zone of crops. Three-hundred observation wells monitor groundwater levels. (WMIDD, 2004)

Because the high salinity of the WMIDD return flows increased the salinity of the Colorado River, a number of actions have been taken to achieve the salinity standards for delivery to Mexico specified in Minute 242.  The drainage water is pumped into a concrete-lined channel (Main Outlet Drain and Extension, MOD/MODE), which allows it to be either diverted to the main channel of the Colorado River at the NIB above Morelos Dam, or bypassed around the dam through a canal to the Cienega de Santa Clara.   WMIDD has also taken steps within the District to reduce return flows including acreage reduction, improved irrigation scheduling, land-leveling and improvements to ditches and turnouts. (WMIDD, 2004)

McMullen Valley Basin

About 3% of the recent agricultural demand in the planning area is near the communities of Aguila and Wenden-Salome in the McMullen Valley Basin.  There are two irrigation districts but neither the Aguila Irrigation District nor the McMullen Valley Water Conservation District has a consolidated distribution system and all district wells and ditches are privately owned.  Both districts were formed in order to contract water and power from the Colorado River. (ADWR, 1998) Groundwater is currently the only water supply. 

Agricultural demand in the basin has been increasing with an annual average of 89,100 acre-feet of demand during the 2001-2005 time period.  The USGS field investigation in 2007 found  approximately 14,600 acres under irrigation with 79% flood irrigated and 20% drip irrigated.  Cropped acres at the time of the investigation included melons (60%), cotton (19%) and sorghum (8%).  Other crops observed were vegetables (chilis), oats, alfalfa/hay, corn, guayule, pistachio, palm and oats (USGS, 2009)

Agriculture near Salome

Agriculture near Salome in the McMullen Valley Basin

McMullen Valley is one of the few groundwater basins in the state designated for out of basin transportation of groundwater.  About 14,000 acres of agricultural land have already been purchased by the City of Phoenix for transport of groundwater to the Phoenix AMA (ADWR 1994b).

Parker Basin

Irrigation in the Parker Basin represented 22% of the agricultural demand in the planning area in 2001-2005. The annual average Colorado River demand for the basin during that period was 630,600 acre-feet.  A relatively small amount of groundwater, less than 1,000 acre feet, was reportedly pumped for agricultural irrigation. 

Irrigation occurs primarily on the CRIT Reservation and also within the Cibola Valley Irrigation and Drainage District (CVIDD).  As mentioned in the Tribal Demand section, about 72,610 acres were irrigated on the CRIT reservation in 2006.  Of this total, CRIT Farms manages over 15,000 acres of alfalfa, cotton, durum wheat and other crops (CRIT, 2005).

CVIDD was formed in 1962, and in 1964 the southern half of the district was incorporated into the Cibola National Wildlife Refuge.  There is an integrated canal system and all main canals are owned by the district and concrete-lined. On average about 3,550 acres of land are irrigated within CVIDD.  Primary crops are alfalfa, bermuda and cotton, although a variety of other crops are grown including vegetables, wheat and barley. (ADWR, 1998)  Colorado River water is the sole source of water.  CVIDD has a Priority 4 Colorado River entitlement of 12,066 acre-feet and 5th and 6th Priority entitlements totaling 3,500 acre-feet.  The USGS did not visit agricultural lands in the Parker Basin in 2007.

Ranegras ag

Agriculture in the Ranegras Plain Basin

Ranegras Plain Basin

Agricultural demand in the Ranegras Plain Basin averaged 28,800 acre-feet during 2001-2005, all met with groundwater pumping.  Agricultural demand has been relatively stable since 1991 (Table 7.7-8).  In 2007, the USGS found agricultural activity primarily along Vicksburg road north of Interstate 10, and north of Highway 72 in the northern part of the basin. Cropped acres at that time were corn (26%), cotton (19%), barley (17%), jojoba (17%) and smaller acreages of alfalfa/hay, guayule and sorghum. Their investigations found 99% of the irrigation was by drip systems and 1% by sprinkler.  (USGS, 2009)

San Simon Wash Basin

Irrigation in the San Simon Wash Basin appears to be restricted to about 2,200 irrigable acres at the end of Reservation Road 21 near the international boundary.  It is not known how many acres are currently being irrigated. Average annual demand was estimated to be 3,900 acre-feet of groundwater during 2001-2005.  Historic withdrawals were higher, up to 11,300 AFA during the late 1970s.  After 1980, the principal crop was alfalfa, irrigated year round (Hollett, 1985).

Yuma Basin

The Yuma Basin is the largest agricultural demand center in the planning area with 35% of the recent demand, an annual average of 994,200 acre-feet during the 2001-2005 time period.  Of this total demand, 762,000 acre-feet was water diverted from the Colorado River and 232,200 acre-feet was water pumped from wells.  Annual demand has increased by over 77,000 acre-feet on average since 1991.  Agricultural lands surround Yuma and extend through much of the western part of the basin from north of Fortuna Foothills to San Luis. 

Bureau of Reclamation Projects

Two Reclamation projects serve irrigation water in the basin – the Gila Project and the Yuma Project.  Water for the Gila Project is diverted at Imperial Dam and delivered via the Gila Gravity Main Canal.  The project is separated into the Wellton-Mohawk Division (discussed previously) and the Yuma Mesa Division.  The Yuma Mesa Division includes three irrigation districts in the basin: Yuma Mesa Irrigation and Drainage District (Yuma Mesa IDD), North Gila Irrigation District (North Gila ID) and Yuma Irrigation District (Yuma ID).  (USBOR 2007f) 

The Yuma Project includes lands in both Arizona and California.  In Arizona, the project is divided into the Valley Division and the Yuma Auxiliary Division. The Valley Division consists of the Yuma County Water Users Association (YCWUA).  Water for the Valley Division is diverted at Imperial Dam into the All-American Canal to the Yuma Main Canal, then through the siphon under the Colorado River at Yuma and into the Valley Division canals. Water for the Yuma Auxiliary Division, also referred to as Unit “B”, is diverted at Imperial Dam and conveyed via the Gila Project Canals to the Unit “B” Irrigation District (Unit “B” ID) (see Figure 7.0-14).

Irrigation Districts

A total of eight irrigation districts operate in the basin (see Figure 7.0-18).  The western part of the Wellton-Mohawk Irrigation and Drainage District extends into the basin and is discussed above in the Lower Gila Basin section.  The general location of the water delivery and drainage infrastructure in the Yuma area including canals, conduits, drains and drainage wells is shown in Figure 7.0-14 and 7.0-21.

Agriculture in Yuma Basin

Agriculture in the Yuma Basin

Figure 7.0-21 Yuma area drainage fields and conduit systems

Figure 7.0-21

The three Gila Project/Yuma Mesa Division irrigation districts have a shared 3rd priority entitlement of 250,000 AFA on 37,187 acres.  In addition, North Gila Valley ID has 1st and 2nd Priority entitlements, and Yuma Mesa IDD and Yuma ID have 2nd Priority consumptive use entitlements (see Appendix C).

Crops grown on Yuma Mesa IDD lands (the Mesa Unit) include citrus, alfalfa hay and seed, peanuts, cotton and grains.  There are about 25,000 irrigated acres in the district.  Crops grown on North Gila ID and Yuma ID lands (North and South Gila Units) include alfalfa, cotton, melons, citrus, winter vegetables and Bermuda grass seed (USBOR, 2007f).  About 6,300 acres of the North Gila ID and 9,600 acres of the Yuma ID are irrigated (Yuma Area Ag Council, 2004).  The South Gila Valley Unit of the Yuma Mesa Division consists of 24 drainage wells (Figure 7.0-21). Water is conveyed to the Gila River Pilot Channel and the Colorado River to become part of the Treaty water delivered to Mexico. (USBOR, 2007g)

Unit “B” ID is a relatively small district that operates and maintains the water distribution facilities of the Yuma Auxiliary Project. It distributes water to about 3,400 acres of land on the Yuma Mesa. Crops are almost entirely citrus including grapefruit, oranges and lemons. (USBOR, 2007h)  The district has a 1st Priority diversion entitlement of 6,800 acre-feet and an unquantified 2nd priority diversion entitlement.

YCWUA provides water to the Yuma Valley south of Interstate 8. It encompasses all of the Colorado River flood-plain land, approximately 53,000 acres, between the City of Yuma and the international boundary.  YCWUA assumed operation and maintenance of Valley Division works of the Yuma Project in 1951 and the Siphon Drop Power Plant 1962.  There are approximately 28,800 irrigable acres in the district (Yuma Area Ag Council, 2004).  YCWUA has an annual Colorado River entitlement of 254,200 acre-feet or, the consumptive use for irrigation of 43,562 acres (whichever is less) of 1st and 4th Priority water.  Principal crops grown are lettuce and other produce crops in the fall and winter months and wheat, cotton, hay, and melons in the spring and summer months.  In 2003, YCWUA received funding to line a number of its earthen canals to reduce seepage and conserve water. (BECC, 2003)

Excess irrigation water from the Valley Division of the Yuma Project is removed via an open drain that runs through the center of the division and terminates at the Boundary Pumping Plant at the international boundary (see Figure 7.0-21).  The main drain and its branches total 56 miles in length. This drainage system is supplemented by 16 drainage wells located along the east side of the Yuma Valley that intercept groundwater flows from Yuma Mesa. YCWUA operates 11 of the wells and Reclamation operates the others.  Most of this pumped water is discharged into the open drain. At the Boundary Pumping Plant, the drainage water is discharged into the bypass canal that flows into Mexico (USBOR, 2007i).

Gila Monster Farms is a relatively small operation located north of the Yuma ID and west of the Wellton-Mohawk IDD.  It has 1st Priority diversion rights of 780 AFA and 3rd, 4th, 5th and 6th priority rights for a total entitlement of 9,156 acre-feet (see Appendix C).  Water is delivered through the Gila Gravity Main Canal.  In 2002, the total irrigated area covered 1,780 acres.

Hillander “C” Irrigation and Drainage District, located north of the international boundary east of San Luis, pumps groundwater to irrigate about 2,300 acres within the 3,440 acre district. Historic use was between 15,000 and 20,000 AFA for irrigation of citrus and asparagus. Center pivot systems in the area suggest that alfalfa or other crops may be grown.  The District is located adjacent to the 242 well field and has a contract to pump up to 4,000 acre-feet of water annually from the 242 Lateral (see Section 7.0.6).

 

water drop  Continue to Section 7.0.7 Cultural Water Demand - Industrial Demand

 

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