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However, as indicated previously, most of the copper generally was transported into and out of the reservoir in the dissolved fraction during the post-peak snowmelt, summer-flow, storm-runoff, and base-flow periods; and generally more than 90 percent of the copper that was transported into and out of the reservoir during post-peak snowmelt and summer-flow periods was in the dissolved fraction (fig. 10). During the post-peak snowmelt and summer-flow periods, about 75 percent of the approximately 38 tons of total copper that entered the reservoir was transported out of the reservoir (table 5; fig. 13). Overall, during the study, an estimated 39 tons of total copper was discharged from the reservoir downstream to the Alamosa River, and an estimated 22 tons of total copper remained in the reservoir. Between April I and November 7, 1994, the period when water was released from the reservoir, the dissolved-copper load transported out of the reservoir was about 87 percent of the dissolved-copper load transported into the reservoir, and the total-copper load transported out of the reservoir was about 64 percent of the total-copper load transported into the reservoir (table 5). Cadmium Throughout the study, cadmium was transported into and out of the reservoir almost entirely in the dissolved fraction (fig. 10). Daily total-cadmium loads ranged from less than 0.1 to about 6.5 lbs (table 7). The maximum daily total-cadmium load occurred on the same date, June 8, as the maximum daily total-copper load. In general, most of the cadmium load was transported through the reservoir (table 5). The data indicate that between about 75 and 85 percent of the total-cadmium load that entered the reservoir during the peak and post-peak snowmelt periods was transported out of the reservoir. Overall, less than 2751bs of total-cadmium load entered the reservoir, and less than 239 Ibs of total cadmium was transported out of the reservoir (table 5). Between April I and November 7, 1994, the period when the reservoir was releasing water, the cadmium load transported out of the reservoir was nearly equivalent to the cadmium load transported into the reservoir (table 5). Manganese Large variations in manganese loads occurred during the study (fig. 14). The largest daily manganese loads were transported into and out of Terrace Reservoir during the peak snowmelt period (fig. 14). During the peak snowmelt period, the maximum daily total-manganese load that entered the reservoir was about 2,230 Ibs (table 7), or slightly more than I ton. The maximum daily total-manganese load occurred on June I, 1994, the same date as the maximum aluminum and iron loads and about a week earlier than the maximum daily copper and cadmium loads (table 7). Large daily total-manganese loads also were transported into the reservoir during rainstorms during the summer period. Most of the total-manganese loads that entered the reservoir during rainstorm runoff did not appear to have been transported out of the reservoir (fig. 14). The smallest daily manganese loads occurred during the base-flow period between November 1994 and February 1995 (fig. 14). Throughout the study, most of the manganese was transported into and out of the reservoir in the dissolved fraction (fig. 10). However, during the peak snowmelt period, between 20 and 30 percent of the manganese was transported into the reservoir in the suspended fraction (fig. 10). About 90 percent of the 52.5 tons of total- manganese load that entered the reservoir was transported out of the reservoir, indicating that the reservoir was a sink for only a small fraction of manganese (table 5; fig. 14). About 55 percent of the annual total-manganese load was transported into and out of the reservoir during the peak and post-peak snowmelt periods (table 5). Zinc The maximum daily total-zinc load of about 943 Ibs entered the reservoir on June 8, 1994, the same date as the maximum daily total-copper and total-cadmium loads and about a week later than the maximum daily total-aluminum, iron, and manganese loads (table 7). Although the maximum daily load occurred at the end of the peak snowmelt period, the largest zinc loads were transported into and out of the reservoir during the post-peak snowmelt period (table 5; fig. 15)---a period when streamflow had substantially diminished. METAL LOADS INTO AND OUT OF TERRACE RESERVOIR 33 r(J31:10