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Central Highlands Planning Area Hydrology -Surface Water (Agua Fria and Salt River Watersheds)

Click to view Figure 5.0-5

Figure 5.0-5 Central Highlands Planning Area USGS Watersheds

The U.S. Geological Survey (USGS) divides and subdivides the United States into successively smaller hydrologic units based on hydrologic features.  These units are classified into four levels. From largest to smallest these are: regions, subregions, accounting units and cataloging units.  A hydrologic unit code (HUC) consisting of two digits for each level in the system is used to identify any hydrologic area (Seaber et al., 1987).  A 6-digit code corresponds to accounting units, which are used by the USGS for designing and managing the National Water Data Network.  There are portions of three watersheds in the planning area at the accounting unit level: the Agua Fria River-Lower Gila River, the Salt River and the Verde River (Figure 5.0-5).

The Agua Fria-Lower Gila River Watershed

The Agua Fria-Lower Gila River Watershed extends from near Prescott to south of Gila Bend in the Lower Colorado River Planning Area.  It includes the drainage areas of the Agua Fria River, the Hassayampa River and the Gila River from below its confluence with the Salt River to Painted Rock Dam.  Within the planning area, this watershed covers the Agua Fria and the Upper Hassayampa basins. 

The Agua Fria River drains an area of about 2,700 square miles with elevations ranging from 7,800 feet in the Bradshaw Mountains, which define part of its western boundary, to 1,570 feet at Lake Pleasant, which is impounded by New Waddell Dam at the southern boundary of the Agua Fria Basin.  The Agua Fria River only flows below the dam when water is released during major flood events and is tributary to the Gila River a short distance downstream of the confluence of the Salt and Gila Rivers near Goodyear in the Phoenix AMA.  The Agua Fria River is perennial along several reaches within the Agua Fria Basin: above Lake Pleasant south of Black Canyon City; through portions of the Agua Fria National Monument; and in the northern part of the basin (see Figure 5.1-5).  Tributaries to the Agua Fria River with perennial reaches include Little Ash, Sycamore and Silver creeks.  Other tributaries to the river are generally intermittent or ephemeral.

The Agua Fria River drains an area of about 2,700 square miles with elevations ranging from 7,800 feet in the Bradshaw Mountains, which define part of its western boundary, to 1,570 feet at Lake Pleasant, which is impounded by New Waddell Dam at the southern boundary of the Agua Fria Basin.  The Agua Fria River only flows below the dam when water is released during major flood events and is tributary to the Gila River a short distance downstream of the confluence of the Salt and Gila Rivers near Goodyear in the Phoenix AMA.  The Agua Fria River is perennial along several reaches within the Agua Fria Basin: above Lake Pleasant south of Black Canyon City; through portions of the Agua Fria National Monument; and in the northern part of the basin (see Figure 5.1-5).  Tributaries to the Agua Fria River with perennial reaches include Little Ash, Sycamore and Silver creeks.  Other tributaries to the river are generally intermittent or ephemeral.

Agua Fria River

Agua Fria River near Black Canyon City.  The Agua Fria River is perennial along several reaches within the basin: above Lake Pleasant south of Black Canyon City; through portions of the Agua Fria National Monument and int he norther part of the basin.

The Hassayampa River originates in the northern Bradshaw Mountains and flows through the Upper Hassayampa Basin and the Phoenix AMA to its confluence with the Gila River.  The river drains a total of about 1,470 square miles.  It is perennial in the northern portion of the Upper Hassayampa Basin in the vicinity of Groom Creek, and in a reach south of Wickenburg.  A major fault crosses the river seven miles downstream from Wickenburg at “the Narrows”, which forms the southern boundary of the basin.  At this point, the entire flow of the river sinks into the streambed.  The only other perennial reaches within the basin are short reaches of Minnehaha, Ash, Weaver and Antelope creeks (AGFD, 1993).

Three streamflow gages are currently active in the watershed; all located in the Agua Fria Basin.  Included are real-time gages on the Agua Fria River near Humboldt, Mayer and Rock Springs.  The maximum recoded annual flow in the watershed was 360,541 acre-feet at the Rock Springs gage in 1992.  The median annual flow at this location is 19,692 acre-feet and the minimum annual flow was 1,528 acre-feet in 1975 (see Table 5.1-2).  There are currently no operating streamflow gages in the Hassayampa River drainage of the watershed.  The gage with the longest record (35 years), located north of Wickenburg, was discontinued in 1982.  During its period of operation, the highest annual flow recorded was 123,076 acre-feet in 1980, and its median flow was 7,457 acre-feet (see Table 5.4-2).

There are approximately 460 total springs in the watershed. Only five springs with a discharge of 10 gpm or greater have been reported; all located in the Agua Fria Basin.  Discharges from those major springs were last measured during or prior to 1982, therefore these rates may not be indicative of current conditions. The largest spring, Castle Spring, discharges approximately 340 gpm from Precambrian rocks at a temperature of 131°F.  Castle Spring is located northwest of Lake Pleasant at Castle Hot Springs, reportedly Arizona’s first resort, opened in 1896.  The four other major springs have discharge rates less than 100 gpm and are located in the northeastern portion of the basin (see Figure 5.1-5).  There are 14 minor springs (discharge of 1-10 gpm) in the watershed, also located in the Agua Fria Basin.  While there are no major or minor springs reported in the Upper Hassayampa Basin, there are approximately 164 to 166 springs with a discharge of less than 1 gpm. 

Within the watershed, reaches of Turkey Creek in the Agua Fria Basin, and Cash Mine Creek, French Gulch and the Hassayampa River in the Upper Hassayampa Basin have surface waters with impaired water quality.  Parameters of concern include cadmium, copper, zinc, pH and lead due to mining activities in the area.

Salt River

Salt River.  The Salt River and Tonto Creek basins comprise most of the watershed.

The Salt River Watershed

The surface water characteristics of the Salt River Watershed are influenced by precipitation patterns, topography and geology.  The Salt River and Tonto Creek basins comprise most of the watershed with the exception of the westernmost part, which extends to the confluence of the Salt and Gila rivers in the Phoenix AMA.  The Salt River is the largest tributary of the Gila River with a drainage area of about 5,980 square miles.  Its headwaters are the White and Black rivers that originate in the high elevations of the Salt River Basin where winter snow accumulation is critical to downstream water supplies.  This area is the most prolific producer of surface water in Arizona with unit runoff values as high as 674 acre-feet/square mile (12.6 inches) in the drainage of the East Fork of the White River. (See Figure 5.2-4).   By comparison, the Tonto Creek Basin has a unit runoff of about 160 acre-feet/square mile (3.1 inches).  (ADWR, 1992) Within the planning area, the elevation of the watershed ranges from near 11,400 feet in the White Mountains to 1,500 feet at Saguaro Lake.

There are many perennial streams in the Salt River Watershed, particularly in the Salt River Basin (see Figures 5.2-5 and 5.3-5). The Salt River and Tonto Creek are both perennial throughout their lengths in the planning area.  Numerous small streams that begin along the Mogollon Rim and the White Mountains feed tributaries of the Salt River and Tonto Creek.  Perennial flow in these streams is primarily due to geologic features (e.g. joints and fractures) that cause groundwater to surface and discharge to streams.

Surface water from the watershed flows into Theodore Roosevelt Lake, and is subsequently released to a series of three downstream reservoirs along the Salt River, Apache Lake, Canyon Lake and Saguaro Lake.  These reservoirs and their associated dams are operated by the Salt River Project (SRP) for the benefit of agricultural, municipal and industrial users in the Phoenix metropolitan area.  Figure 5.0-6 shows the capacity of the SRP reservoir system on both the Salt and the Verde rivers.  Also shown is C.C. Cragin Reservoir, formerly known as Blue Ridge Reservoir. Water stored at C.C. Cragin, located in the Eastern Plateau Planning Area, is diverted by pipeline to the East Verde River in the Verde River Watershed to supplement the SRP water supply and satisfy obligations to the Gila River Indian Community in accordance with the Arizona Water Settlement Act (Act).  The Act also allocated 3,500 AFA from the reservoir to improve the water supply situation in northern Gila County, of which 3,000 AFA will be used by Payson. Surface water stored in the Salt and Verde reservoir system is generally not available for use in the Central Highlands Planning Area.

Salt/Verde capacity

Figure 5.0-6 SRP Reservoir System Capacity

The Salt River system dams were constructed beginning in 1911 with completion of Roosevelt Dam.  Mormon Flat Dam was completed in 1926, followed by Horse Mesa in 1927 and Stewart Mountain in 1930.  Prior to dam construction, the flow in the Salt River was heaviest in the spring and early summer.  Flow is now regulated in response to flood control and downstream water demand.  As a result, flows below the reservoirs are generally highest during June-August when water demand is greatest in the Phoenix metropolitan area or when high inflow to the reservoirs necessitates release of water from the dams.  In February 1980, a wet winter combined with a storm that dropped up to ten inches of rainfall on the watershed resulted in the largest controlled flood ever to go down the Salt River.  Releases from Roosevelt Dam peaked at 180,000 cfs and the water level behind the dam was inches from overflowing the crest (SRP, 2007). 

 

 

For more information on surface water in the Central Highlands Planning Area see Streams (for surface water conditions) and Springs (for perennial/intermittent streams and springs) in the menu to the right.

water drop Click here to continue to Section 5.0.2 Hydrology - Surface Water (Salt River and Verde River watersheds)

 

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References and Supplemental Reading for the Central Highlands Planning Area Overview

Colorado River Central Highlands Planning Area Download entire Central Highlands Planning Area Atlas in pdf Verde River Lake Pleasant