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Hydrology of the Southeastern Arizona Planning Area - Surface Water Hydrology

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Figure 3.0-5 Southeastern Arizona USGS Watersheds

(Data source: USGS 2005)

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 five watersheds in the planning area at the accounting unit level: Middle Gila River; Rio Bavispe; San Pedro River; Santa Cruz River; and the Upper Gila River (Figure 3.0-5).  More detailed information on stream flow, springs, reservoirs and general surface water characteristics are found in the individual basin sections.

Middle Gila

The Middle Gila Watershed extends west from Coolidge Dam to the confluence of the Gila and Salt rivers in the Phoenix AMA.  The San Pedro River is the major tributary to this watershed in the Southeastern Arizona Planning Area.  Dripping Springs Wash, Donnelly Wash and the northernmost part of the Lower San Pedro basins are included in the Watershed. 

Below Coolidge Dam, flow in the Gila River is from releases from the San Carlos Reservoir and flood flow from the San Pedro River (ADWR, 1994). Perennial streams include the Gila River, and portions of the San Pedro River and Mineral Creek in the Lower San Pedro Basin, Box Canyon in the Donnelly Wash Basin and Mescal Creek in the Dripping Springs Wash Basin (see Figures 3.8-6, 3.5-5 and 3.6-5).

Since 1936, an average of 260,000 AFA of reservoir storage and inflows have been released to the river below Coolidge Dam (ADWR, 2006).  There are three streamgages in the watershed. The highest annual flow was recorded at the Kelvin gage where a flow of 2.375 maf was measured in 1993. Annual median flow at this gage is approximately 324,300 acre-feet (see Table 3.8-2). This gage is located downstream of the confluence of the San Pedro and Gila rivers.

Gila River in the Donnelly Wash Basin

Gila River, Donnelly Wash Basin.  Below Coolidge Dam, below in the Gila River is from releases from the San Carlos Reservoir and flood flow from the San Pedro River.

There are two major (10 gpm or greater) springs in the watershed, both located in the Dripping Springs Wash Basin. Both are warm springs with measured discharges of 200 gpm (Mescal Warm Spring) and 165 gpm (Coolidge Dam Warm Spring). These measurements were taken during or prior to 1982 and may not be indicative of current conditions.

Ten miles of Mineral Creek, located northwest of Kearny, are impaired due to elevated concentration of copper and selenium.

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Rio de Bavispe

The Rio de Bavispe Watershed drains south and extends into New Mexico and Mexico. Major drainages in Arizona are Whitewater Draw and Black Draw which are tributary to the Rio de Bavispe in Mexico. The Rio de Bavispe joins the Rio Yaqui which discharges into the Gulf of California. The watershed includes most of the Douglas Basin, the southernmost portion of the Willcox Basin, and the entire San Bernardino Valley Basin. Whitewater Draw is the major drainage in the Douglas Basin. Black Draw is the main surface water drainage in the San Bernardino Valley Basin and becomes perennial just north of the international boundary.  In this basin, artesian wells and springs support wetlands near the border. In addition to Black Draw, perennial streams in the watershed include reaches of Rucker Canyon in the Willcox Basin, and Leslie Creek in the Douglas and Willcox basins (see Figure 3 .5-5 and Figure 3.14-5).

There are two active streamgages in the watershed. The gage at Whitewater Draw near Douglas recorded a maximum annual flow of approximately 22,300 acre-feet in 1955 with a median annual flow of 5,960 acre-feet. The other operating gage is on Leslie Creek near McNeal with a median annual flow of approximately 750 acre-feet. There are no major springs in the watershed.

Charleston gage on San Pedro River

San Pedro River at Charleston, Upper San Pedro Basin.

San Pedro-Willcox Watershed

The Arizona portion of the San Pedro River Watershed is contained entirely within the planning area.  Approximately 696 square miles of the Watershed extends into Mexico. In Arizona, the Watershed includes all of the Aravaipa Canyon and Upper San Pedro basins, most of the Lower San Pedro and Willcox basins and relatively small portions of the Cienega Creek, Douglas and San Rafael basins.  A few tributaries to the San Pedro River begin on the southwest slopes of the Huachuca Mountains in the San Rafael Basin and drain into Mexico. (ADWR, 2005a) The San Pedro River enters the U.S. from Mexico near Palominas (see Figure 3.13-1) and flows north to its confluence with the Gila River. Major tributaries are the Babocomari River and Aravaipa Creek.

With the exception of Whitewater Draw in the extreme southern end of the basin that drains into the Douglas Basin, most of the surface water drainage in the Willcox Basin is to the Willcox Playa.  The playa occupies about 50 square miles in the center of the basin and is a remnant of Pleistocene-age Lake Cochise. (Oram, 1993) 

Some stretches of the San Pedro River are perennial, although recent drought and delay of the summer monsoon has affected some previously perennial stretches for short periods of time, most notably at Charleston in the Upper San Pedro Basin. The Babocomari River, in the Upper San Pedro Basin, is perennial in its upper reach. Aravaipa Creek is perennial within Aravaipa Canyon above its confluence with the San Pedro River as are three of its tributaries in the Aravaipa Canyon Basin (see Figures 3.1-5 and 3.8-6).  Other perennial streams are found in the Lower San Pedro, Upper San Pedro and Willcox basins (Figures 3.8-6, 3.13-5 and 3.14-5).

There are 12 active streamgages in the watershed; two in the Lower San Pedro Basin and 10 in the Upper San Pedro Basin. The gage on the San Pedro River at Charleston has been in operation since 1904. The largest annual flow ever measured in the watershed, (152,798 acre-feet), was recorded at this gage in 1914.  More recently, in 1984, a maximum annual flow of 102,107 acre-feet was measured at the gage on the San Pedro River near Tombstone.  Median annual flow at these gages is 33,203 acre-feet and 29,654 acre-feet, respectively.

The only major springs in the watershed are found in the Lower San Pedro and Upper San Pedro basins. There are 14 major springs in the Lower San Pedro Basin. The largest, Cooks Lake Spring, had a discharge rate of 1,000 gpm when last measured in 1951.  Twelve major springs have been identified in the Upper San Pedro Basin. The largest is Garden Canyon No.1 with a discharge of 134 gpm measured in 1963. Most of the spring measurements in both basins date from before 1980 and may not be indicative of current conditions (see Tables 3.8-5 and 3.13-5).

Fifteen miles of the San Pedro River in the Lower San Pedro Basin from Aravaipa Creek to the Gila River are impaired due to elevated concentrations of E. coli and selenium (Table 3.8-7). In the Upper San Pedro Basin, water quality standards were exceeded in three reaches of the San Pedro River for a total of 53 miles. These reaches are impaired due to elevated levels of E. coli, nitrate and copper (Table 3.13-6).

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Santa Cruz Watershed

The Santa Cruz Watershed includes most of the Cienega Creek and San Rafael basins and extends south into Mexico and west to include the Santa Cruz AMA and most of the Tucson and Pinal AMAs. The Santa Cruz River originates in the San Rafael Valley and flows southward to Mexico before turning north and reentering the U.S. east of Nogales, Arizona.  Surface water in the Cienega Creek Basin drains west to the Santa Cruz River from Sonoita Creek and north to tributaries of the Santa Cruz River from Cienega Creek.

The Santa Cruz River is perennial in the planning area.  In the Cienega Creek Basin there are perennial reaches of Cienega Creek, Sonoita Creek and Red Rock Canyon. The only streamgage on the Santa Cruz River is near Lochiel with a maximum annual flow of 12,600 acre-feet measured in 1955. Median flow at this gage is 1,410 acre-feet. The only other streamgage in the watershed is a gage on Cienega Creek near Sonoita (see Table 3.3-2).

Major springs are located only in the Cienega Creek Basin.  The largest of the seven major springs is Monkey Spring with a discharge rate of 430 gpm.  A measurement date is lacking for this spring (Table 3.3-5). 

There are several impaired waters in the Santa Cruz Watershed. Parker Canyon Lake in the San Rafael Basin contains elevated levels of mercury.  In the Cienega Creek Basin, a total of 20 miles of impaired stream reaches occur on Alum Gulch, Harshaw Creek, Humboldt Canyon and on an unnamed tributary to Harshaw Creek. These waters contain concentrations of cadmium, copper, zinc or pH that exceed standards (Table 3.3-6).

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Headwaters of the Santa Cruz River

Santa Cruz River near the

headwaters, San Rafael Basin

Upper Gila Watershed

The Upper Gila Watershed drains about 7,400 square miles in the planning area above Coolidge Dam and contains the Bonita Creek, Duncan Valley, Morenci, and Safford basins.  Major tributaries include the San Francisco River, Eagle Creek, Bonita Creek, San Simon Creek and the San Carlos River. 

An average of about 160,000 AFA of Gila River water flows into Arizona from New Mexico and over 40% of this flow typically occurs in the winter. Tributary inflows from the San Francisco River are significant, typically over 150,000 AFA.  Inflow to the San Carlos Reservoir from the Gila and San Carlos Rivers averages about 310,000 AFA (ADWR, 2006).  There are three active streamgages on the Gila River. The maximum annual flow recorded was at a gage near Solomon with a flow of 1.56 maf in 1993.  Median flow at this gage is approximately 273,000 AFA (see Table 3.10-2).

The San Francisco River is perennial with a number of hot springs located above Clifton. The Gila River has a 35-mile perennial stretch about 20 miles northwest of the New Mexico border. Flow in this stretch is maintained by tributary inflow and springs, including hot springs (ADWR, 1994). Flow in the Gila River becomes intermittent farther downstream due to irrigation diversions and seasonal variations in flow (ADWR, 2006).

Upper Gila River in the Duncan Valley Basin

Upper Gila River near Three Way in the Duncan Valley Basin.  The Gila River has a 35-mile perennial reach about 20

miles northwest of the New Mexico State line.  Flow in the River becomes intermittent downstream due to irrigation

diversions and seasonal variations in flow.

The largest spring in the planning area is located in the Safford Basin.  Warm Springs, with a measured discharge of almost 3,400 gpm is located at the headwaters of the San Carlos River.  There are also a number of large springs downstream of Pima near the Gila River (USGS, 2006c). In total, there are 22 major springs in the Safford Basin. Other major springs are found in the Bonita Creek Basin (1 spring), Duncan Valley Basin (2), and Morenci Basin (9).  Most of the spring measurements shown on the springs tables in sections 3.2, 3.7, 3.9 and 3.10 were taken between 1940 and 1982 and may not be indicative of current conditions.

In the Safford Basin, a 6-mile reach of the Gila River exceeded the water quality standard for E.coli and turbidity and a 8-mile reach of Cave Creek exceeded the standard for selenium (Table 3.10-7).  In the Morenci Basin, water quality standards were exceeded at Luna Lake and in a 13-mile reach of the San Francisco River near Alpine (Table 3.9-7).

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

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Santa Cruz River

Flowers in San Rafael Valley