PANTANO WASH NEAR VAIL (09484600)

GILA RIVER AT CALVA (09466500)

(March 6, 1932). The Gila River was ravaged by floods in the 1910s and 1920s, including one flood estimated at 100,000 ft³/s in 1916. This upstream view from the railroad bridge at Calva shows a wide, braided channel. An open cottonwood gallery forest appears in the midground at left (channel right), and the low shrubs at right appear to be native willows (W.E. Dickinson, #1053).

(June 18, 1964). In the intervening 32 years, the highest discharge through this reach was 27,900 ft³/s on October 1, 1941. Dense tamarisk has become established, creating a floodplain where the main channel once was. The channel has shifted to the right and is much smaller than it was in 1932 (Raymond M. Turner).

(October 17, 1973). To reduce evapotranspiration, phreatophytes (mostly tamarisk) were removed from this reach in 1970, and the floodplain was reseeded to native grasses. Those grasses are mostly gone at the time of this photograph, one year after a flood of 80,000 ft³/s passed through this reach. The small shrubs throughout the view are mostly tamarisks that are re-establishing in the reach (Raymond M. Turner).

(May 21, 1984). In October 1983, a flood of 150,000 ft³/s passed through this reach in the wake of Tropical Storm Octave. This flood followed one that peaked at 100,000 ft³/s in 1978. These floods shifted the channel back into the view, and driftwood racks appear throughout the foreground. Despite this flood, dense tamarisk appears on both floodplains (Raymond M. Turner).

(October 6, 2000). Except for withdrawals of domestic and irrigation water at low-head diversion dams, the Gila River is unregulated upstream from Calva. In January and February, 1993, three floods passed through this reach that exceeded 100,000 ft³/s. Despite these floods, tamarisk has grown considerably, blocking the view of the river channel from this camera station. Despite the enormous effort at tamarisk removal and river restoration, the tamarisk has attained a higher biomass than it had in 1964. The channel has shifted from the right side to the left side of this view (Dominic Oldershaw, Stake 331a).

GILA RIVER AT KELVIN (09474000)

(May 21, 1945). This view, from a hill on the south side of the Gila River, shows the bridge at Kelvin from which discharge measurements are made at high flows. The river flows from right to left in this view and is regulated by Coolidge Dam, completed in 1928. The largest historic flood at this station is 132,000 ft³/s in 1916, and three other annual flood peaks exceeded 40,000 ft³/s before 1945. Floods were less than 40,000 ft³/s for 15 years prior to this photograph. Tamarisk is becoming established in the foreground, and mesquite and cottonwood trees appear on the far bank. Mineral Creek, spanned by a railroad bridge, enters the Gila River at left (W.L. Heckler, #3709).

(October 2, 2000). The view is blocked by cottonwood trees, particularly at left and right with small trees in the foreground, and large tamarisk trees. This increase in riparian vegetation has occurred despite the fact that floods of 100,000 and 74,900 ft³/s, in 1983 and 1993 respectively, passed through this reach (Dominic Oldershaw, Stake 430).

GILA RIVER BELOW BLUE CREEK (09432000)

(July 23, 1931). The Gila River upstream from its juncture with Blue Creek near the Arizona-New Mexico border drains 3,203 mi2 of rangeland and the Gila Wilderness. Just downstream from Blue Creek, the channel is somewhat confined within a bedrock canyon, but just upstream, as this view shows, the valley is relatively wide (James Baumgartner, #1501).

(June 11, 1964). By 1964, cottonwood trees had grown up along the banks of the river behind a lower ribbon of tamarisk trees. The channel position is the same despite a flood of 41,700 ft³/s in 1941 (Raymond M. Turner).

(October 5, 2000). The channel has shifted to the left, possibly during one of the four floods that exceeded 27,000 ft³/s between 1964 and 2000. The cottonwood gallery has been destroyed, and the channel is lined with tamarisk and coyote willows with scattered brickellbush (Dominic Oldershaw, Stake 346a).

SANTA CRUZ RIVER AT TUCSON (09482500)

(November 22, 1930). This downstream view, taken from near the west abutment of the old Congress Street Bridge, shows the wide alluvial channel of the Santa Cruz River. At this time, the river flowed through a rural area, and cottonwood trees lined its banks. The relatively shallow arroyo began downcutting in 1878, and the 1914 flood of 15,000 ft³/s and 1917 flood of 7,500 ft³/s caused the most recent channel change before 1930 (photographer and number unknown).

(December 17, 1994). The channel of the Santa Cruz River is now confined by soil-cemented banks. The open gallery forest of cottonwood trees was destroyed by ground-water pumpage and development, and the channel reached its present depth between 1977 and 1983 (Dominic Oldershaw, Stake 3300).

(August 22, 2000). The bridge was replaced, but its roadway surface was at about the same elevation as the old one. Channel downcutting, which primarily occurred during the 1977 and 1983 floods (the latter had a peak discharge of 52,700 ft³/s), has lowered the bed by up to 9 feet. Because of persistent problems with lateral channel change, soil cement now stabilizes the channel banks (Dominic Oldershaw, Stake 298).

SAN PEDRO RIVER AT CHARLESTON (09471000)

(May 4, 1954). The gaging station for the San Pedro River at Charleston has one of the longest records in Arizona. In 1954, the gaging station was at this site, about a quarter mile downstream from the current station on the highway bridge. This view shows the cableway cross section used for discharge measure-ments. The view is to the east, and the river flows from right to left. The trees along the far bank are cottonwoods (C.A.B., #4251).

(July 29, 2000). Cottonwoods and willows, with scattered tamarisk, now block most of the view. The railroad on the opposite bank is still in operation (Dominic Oldershaw, Stake 296).

SANTA CRUZ RIVER NEAR LOCHIEL (09480000)