Gila River



Report by Marc W. McCord

Coolidge Dam to Kelvin
~ 40 Miles

The Gila River is a major waterway for Arizona, though flows (and especially navigable flows) are rare. It usually runs in the early to late spring, when snows melt in the San Francisco Mountains of Apache National Forest in far western New Mexico. The river begins as three forks (North Fork, Middle Fork and South Fork) north of Silver City and west of Truth of Consequences. From its headwaters the Gila River flows west through Safford, Florence, Glendale and Yuma, then into California along the Mexico border to the Colorado River. The Gila River has three major tributaries in the San Carlos, San Francisco and San Simon Rivers in southeastern Arizona.


At the bottom of San Carlos Lake, about 30 miles below Bylas, is Coolidge Dam, which regulates Gila River flow with its releases, supplemented by very occasional thunderstorms that give the river a temporary bump. Access is via the county road that veers left off US Highway 70 at Bylas, then driving about 30 miles to the river just below the dam. (NOTE: Access near the base of the dam MAY be restricted, or banned completely, by order of the Department of Homeland Security amid concerns that terrorists may attempt to damage or destroy dams, causing floods that kill many and cost billions of dollars to repair. Check with the US Army Corps of Engineers at Coolidge Dam for information regarding river access below the dam.) Take a visual cue off the water level, current and dam outflow to get a feel for downriver conditions. Water will almost always flow in this section, though not always at navigable levels. Expect the best flows about 1-2 days after a major rainstorm event in the drainage basin above San Carlos Lake that prompts a dam release, though this reach of the river is usually navigable from May through September.

The upper part of this run begins on a winding river canopied by shade trees of the sycamore, cottonwood and alder species before opening into the typical Arizona desert topography that we all know and love. Many birds, including the Great Blue Heron, call this place "home". Jerusalem Mountain (5,294') is on river left, and the Mescal Mountains are on the right side, about 5-6 miles below the put-in. Runs descend on a very shallow gradient with a normally slow current as the river flows to the desert floor between Phoenix and Casa Grande about halfway between its headwaters and its rendezvous with the Colorado River. With a good current a strong paddler could run this reach in a day, though most will take 2-3 days for the entire run. Take along plenty of drinking water! Hayden, a small town about midway through the run, has access, food, supplies, and accommodations for those not wanting to camp in a tent. Trips can end or start here depending upon downriver conditions. Kelvin is about 15 more miles downriver.


Pinal County in southcentral Arizona near the Mexico border. Tucson is the nearest sizeable Arizona city, Nogales, Mexico is just a few miles south of Tucson and Las Cruces is the closest major city in New Mexico. It flows near the Mescal Mountains in southeastern Tonto National Forest on river right (north) and Sonoran desert floor on river left (south).


Tucson 120 miles; Phoenix 125 miles; Flagstaff 263 miles; Albuquerque 448 miles; Durango 579 miles; Grand Junction 749 miles; Denver 918 miles; Salt Lake City 1,034 miles; Oklahoma City 990 miles; Dallas 970 miles; Austin 989 miles; San Antonio 970 miles; Houston 1,175 miles; Little Rock 1,295 miles; Kansas City 1,471 miles (all distances are approximate, depending upon starting point, destination point at the river and route taken.)


When it flows the Gila is usually clean and sandy brown, turning slightly clear if flows are sustained for several days after a significant rainfall. Flows are controlled by releases at Coolidge Dam several miles upriver, and are usually low and slow except right after a flash flood, in which case the river may flow fast and furious, occasionally running out of its banks.


May through September is usually the best time to catch navigable waters in this section of the Gila River, but it can become a boatable stream anytime a significant dam release occurs at San Carlos Lake or right after a major local rainstorm in the drainage basin. Do NOT drive to Arizona specifically to paddle this river!


Other than desert heat during the day, cool to cold nighttime temperatures and the aforementioned snakes and scorpions, there are few hazards in this reach of the Gila River. Flash flooding can produce strong currents and Class II to II+ rapids, but the river is primarily free of obstacles and hazards that pose injury problems for boaters and equipment.


Pinal County Road to the left off US Highway 70 at Bylas about 30 miles to the river at 0.0 miles; Christmas Access, off SH 77, at about 17.0 miles; Winkleman Access, off SH 77, at about 25.0 miles; SH 77 at Hayden Access at about 28.0 miles; Kearney Access at about 34.0 miles; SH 177 Access at Kelvin at about 40.0 miles. There are no other known convenient access points for this reach of the Gila River.


There are no public or private campgrounds located along this section of the Gila River. It is possible to camp alongside the river, but remember that you are in the desert, and take care to avoid desert critters that can harm you, especially at night. If camping on private land or in a public park always leave only footprints and take only photographs. You should always leave the area cleaner than how you found it! Always obtain permission from the rightful owners before camping on private land.


There are at least two commercial outfitters providing rentals, shuttles, guided trips and river information on this reach of the Gila River. Unless contracting with one of them for services bring everything you need and run your own shuttles.


This reach of the Gila River usually has a navigable flow from May through September except during extended drought periods, and almost no navigable flow at other times. Scenery is awesome in a desert sort of way, and there is much to appreciate about this stream when it flows, which is not frequently. There are some gorgeous mountains and foothills along and near this reach of the river, but few signs of civilization other than where the river flows near some highway or county road, in which case you will see vehicles carrying people and cargo, but not stopping unless there is an emergency. The trip begins in an area of tree-lined banks that are home to many species of birds, and where shade is often available. However, it ends in a wider plain of desert scrub and lots of Arizona sunshine. With adequate water this trip can be made in one long day, but most boaters will take 2-3 days to enjoy the scenery and the leisurely current. Be prepared for desert riverside camping. The Gila is prone to flash flooding during periods of heavy rainfall, so be prepared, especially when choosing a campsite on overnight trips.

Lower Gila River Watershed

The headwaters of the Gila River originate in the Mogollon Mountains of western New Mexico. The river flows east to west across southern Arizona. The entire Gila watershed drains approximately 57,900 square miles before joining the Colorado River near Yuma; 8,200 square miles of this watershed is within the Lower Colorado River planning area.

The Gila River drains the central and eastern portions of the planning area. Within the planning area boundaries, the Gila River extends from Gillespie Dam, located approximately 45 miles southwest of Phoenix, to the Colorado River confluence, a distance of about 150 miles (Figure 16). The southern portion of the planning area drains southward into Mexico as part of the Sonoyta River watershed. A small basin of 242 square miles in northern Sonora, Mexico, drains northward into Arizona, west of Sasabe. This drainage connects with Vamori Wash in Arizona which returns to Mexico south of Papago Farms (Harshbarger, 1979). Perennial flow does not exist in the southern part of the planning area.

Streamflow Characteristics

Within the Lower Gila watershed, most of the Gila River is ephemeral and flows only in response to precipitation events or water releases from upstream dams. Flow in the lower portion of the Gila River would be intermittent if it were not controlled by dams. Historically, the river would flow in the spring due to winter rains and melting snow, and in summer following monsoon rains (U.S. Geological Survey, 1923). Since the construction of Gillespie Dam in 1921 and Painted Rock Dam in 1959, the flow has been impounded and diverted to agricultural areas or released slowly in the main channel to prevent flooding downstream (U.S. Army Corps of Engineers, 1977).

The Wellton-Mohawk Irrigation District returns surplus irrigation water to the Gila River channel near Dome, Arizona. This influx of water (U.S.G.S. streamgage #09520500) supports flow from Dome to the confluence with the Colorado River.

Table 23 lists the U.S. Geological Survey streamgages maintained on the Gila River within the planning area. The location of these gages are displayed on Figure 16. All other streams that drain into the Gila River are ephemeral and only flow in response to precipitation events (Brown and others, 1981).


Until the 1993 flood events, flow on the Gila River was controlled by two dams; Gillespie and Painted Rock. Gillespie Dam was breached in January, 1993 when a 135(+) foot section of the structure collapsed during flooding. Gillespie Dam is located about 45 miles southwest of Phoenix, at a narrow passage between the Buckeye Hills and the Gila Bend Mountains. The dam was constructed in 1921 to divert water from the Gila River into two canals that would carry irrigation water to nearby fields and to the Gila Bend area (U.S. Geological Survey, 1923). Most of the low flow in the river upstream of Gillespie Dam is sewage effluent and irrigation return flow.

Painted Rock Dam is located northwest of Gila Bend and was constructed in 1959 to control flood waters that periodically damage downstream areas. The Painted Rock Reservoir has a gross capacity of 2 1/2 million acre-feet of storage, but is designed to remain empty most of the time. The reservoir reached full capacity during the 1993 flood events and extensive damage occurred downstream as a result of the high volume of spillwater. During less severe flooding, the dam retains water and releases it relatively slowly until the reservoir is empty. The water is released at a slow rate to minimize downstream damage and still empty the reservoir as quickly as possible (U.S. Army Corps of Engineers, 1977). There is no flow below Painted Rock Dam except during flood events.

Water Quality

The Gila River, from its confluence with the Salt River to Painted Rock Reservoir, has low dissolved oxygen and is contaminated with pesticides, metals, inorganics, and nutrients. Painted Rock and Gillespie Dams appear to act as contaminant sinks and exhibit high levels of pesticides, boron, and organochlorines (Arizona Department of Environmental Quality, 1990). Bioaccumulation of toxic substances in contaminated sediments presents a risk to fish and wildlife, and possibly human health. DDE and toxaphene found in fish tissue at Painted Rock and Gillespie Dams present a threat of reduced viability and recruitment to wildlife resources of the lower Gila River drainage (Kepner, 1987). Pesticide contamination in the Gila River is some of the most significant in the western United States. Agricultural return flows and several municipal discharges feed the rivers.


Station Name Station Number Period of Record Mean Annual Flow (ac-ft) Median Annual Flow (ac-ft) Record Annual High Flow (ac-ft) Record Annual Low Flow (ac-ft)
Gila River above Gillespie Dam 9518000 1941-1971 1974-1990 285,180 56,280 2,793,870 8,690
Gila River below Gillespie Dam 9519500 1922-1990 260,570 27,720 2,735,960 0
Gila River below Painted Rock Dam 9519800 1960-1990 256,630 3,810 2,377,680 80
Gila River near Mohawk 9520360 1974-1990 340,910 410 2,142,450 0
Gila River near Dome 9520500 1906, 1930-1990 400,990 2,750 2,113,500 0
Source: U.S. Geological Survey, 1992, National Water Information System