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unaltered by the Aspinall Unit. Current water temperatures at both sites in the Colorado River (RM 136 and 49) differed from the estimated pre-Aspinall temperatures by a maximum of 0.5 °C (Figure 2, Table A2). Sediment Load The average annual suspended-sediment load of the Gunnison River is highly variable (Elliott and DeFeyter 1986), but has declined as a result of the Aspinall Unit (Figure 3, Table A3). The Aspinall Unit has not reduced the minimum amount of sediment carried by the river, but has reduced year to year variability. Thompson (1984) summarized the suspended-sediment load of the Colorado River near Cisco for 1930-1982 (Figure 4). He attributed a break in the slope of the relation between annual suspended-sediment load and annual stream discharge to the construction of the Aspinall Unit. The slope change indicated that the average annual suspended-sediment load decreased after the construction of Aspinall. Although other factors (e.g. changing land use patterns) may have contributed to reduced sediment loads, the abrupt change in slope at the same time that Blue Mesa was closed suggests that the Aspinall Unit was the primary cause. The reduced sediment load has resulted in larger substrate sizes and an armored bottom in much of the Gunnison River (Stanford and Ward 1983). The changes in the Colorado River are less evident, but may ultimately result in a gradual lowering of the river channel as fine materials are moved downstream and not replaced at an equal rate. Streamflow The greatesr_ change caused by the Aspinall Unit is the reduction of spring runoff. Peak discharge has steadily declined since continuous flow records began in the early 1900's (Figures 5, 6, A3, and A4; Table A4). Mean 14