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Historical data for five structures was replaced with USGS transbasin diversion data in the <br />Phase IIIa ph2_ddh_commands run. This USGS data is unavailable in the current Access <br />version of the Sanjuan Hydrobase; however, some State diversion records for the structures <br />are included in Hydrobase. After conferring with the state, the *.ddh file was created using <br />historical State diversion records for the five structures. The inconsistency does not affect <br />results at the La Plata gages because it occurs in headwaters of other tributaries, and has <br />almost no impact on baseflows at the Bluff gage. <br />It was necessary to add a free water right for Main Canal #2 during Subtask 11.7. Negative <br />baseflows on the order of 104 were occurring below Main Canal #2, which led to discovery <br />that demandts was limiting historical diversions for Main Canal #2 to 1 cfs. Main Canal #2 <br />operates via operating rules in the San Juan model, and has no direct flow rights, except for <br />a 1 cfs decree assigned to the structure in the database. (It is our understanding that in reality <br />Main Canal #2 is an alternate point of diversion for rights that are assigned to Main Canal <br />#1.) Adding a free water right to the rights file effectively removed the -rights limit, and <br />allowed Main Canal #2 historical diversions to be estimated as the average of recorded <br />historical diversions for the appropriate hydrologic condition. <br />Results <br />Compare Baseflows <br />Tables 5 and 61ist the three gages in the San Juan model and six gages in the Yampa model that <br />were chosen for analysis carried out in Approach steps 4 and 5: <br />Table 5 -Key San Juan Basin Stream Gages Chosen for Analysis in Subtask 11.7. <br />USGS Ga a ID Ga a Name <br />09365500 La Plata River at Hes erns, CO <br />09366500 La Plata River at CO-NM State Line <br />09379500 San Juan River nr Bluff, UT <br />Table 6 -Key Yampa Basin Stream Gages Chosen for Analysis in Subtask 11.7. <br />USGS Ga a ID Ga a Name <br />09237500 Yam a River below Sta ecoach Res <br />09239500 Yampa River at Steamboat Springs, CO <br />09244410 Yam a River below Diversion near Ha den, CO <br />09247600 Yam a River at Crai , CO <br />09251000 Yam a River at Maybell, CO <br />09260000 Little Snake River at Lil , CO <br />The time series of baseflows generated in Subtask 11.7 and Phase IIIa for the gages in Table 1 <br />are presented graphically in Exhibit 1. The graphs generally show good agreement between <br />baseflows generated from actual data (Phase IIIa model) and those generated from estimated <br />data (Subtask 11.7). Note that discrepancies are more apparent for the smaller streams because <br />of the graph scale. <br />Appendix E E-83 <br />