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<br />()'3 \. ro <br /> <br />was large during 1957-67; and (4) streamflows <br />from 40 to 280 ft3/s occurred more frequently during <br />1984-92 at site Ql than during 1957-67 at site Q1A, <br />probably as a result of the controlled releases from <br />storage at Trinidad Reservoir. <br />Seasonal streamflow entering the study area <br />between 1957-67 and 1984-92 is shown in figure 5. <br />The daily streamflow measured at site Q1A between <br />1957-67 represents a period of unregulated stream- <br />flows (excluding upstream diversions) that existed in <br />the study area before operation of Trinidad Dam. The <br />daily streamflow measured at site Ql during 1984-92 <br /> <br />500 <br /> <br />450 <br /> <br />400 <br /> <br />o <br />z <br />o <br />&l 350 <br />en <br />ffi <br />0- <br /> <br />m 300 <br />() <br />Oi <br />=> <br />() <br />"'.250 <br />~ <br />-' <br />"- <br />~ 200 <br />t; <br />~ <br />::; <br />~ 150 <br />il <br /> <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br /> <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />\ <br />, <br />\ <br />\ <br />\ <br />\ <br />\ <br />, <br />, <br />, <br />, <br />, <br />, <br />, <br />\ <br />\ <br />, <br />\ <br />\ <br />, <br />, <br />\ <br />\ <br /> <br />SITE Q1. 1984-92 <br /> <br /> <br />" <br />" <br />, <br />,~- <br /> <br />100 <br /> <br />50 <br /> <br />SITE Q1 A. 1957-87 <br /> <br />01 <br /> <br />represents a period when streamflow was regulated <br />by the operation of Trinidad Dam and when demands <br />of PRWCD canal systems near Trinidad and other <br />canal systems in the study area needed to be met. <br />A comparison of streamflow at sites Ql and Q1A <br />(fig. 5A) indicates that regulation of the Purgatoire <br />River at Trinidad Dam has affected the seasonal <br />quantity and timing of streamflow into the study area. <br />Daily median streamflow during 1984-92 (site Ql) <br />Was larger than during 1957-67 (site Q1A) during the <br />summer, but generally was smaller during the other <br />three seasons (fig. 5A). <br /> <br />. <br /> <br /><\ <br /> <br />10 20 30 40 50 60 70 60 90 <br />PERCENT OF TIME INOICATEO STREAMFLOW WAS EQUALED OR EXCEEOEO <br /> <br />Figure 4. Flow-duration curves for the streamflow-gaging stations, Purgatoire River below <br />Trinidad Reservoir (site 01) and Purgatoire River at Trinidad (site 01 A) comparing two different <br />periods of streamflow entering the stUdy area, 1957:-67 and 1984-92. <br /> <br />100 <br /> <br />10 Evaluation of Streamflow Traveltime and Streamflow Gains and LOSBea along the Lower Purgatoire River, <br />Southeastern COlorado, 1984-92 ' <br />