STATION I MILE 1 



STATION 



STATION II MILE 24 



Velocity m.p.s. 



Direction 



of time 



"^ Downstream direction 



RESERVOIR CONDITION 



Period May 26. 1964 



Pool status Filling 



Pool level Minus 12.5 



Inflow 578 cms. 



Spill discharge 



Total discharge 434 c.m.s. 



Figure 11. — Continued 



The infliiencB of the leduced discharge on cur- 

 rents is readily apjaaront. On May 23, a day of 

 surface spill and high total discharge, all three 

 stations showed nearly lOO-jDercent downstream 

 orientation of currents. On May 26, the spill was 

 closed and the total discharge was reduced. Cur- 

 rent direction at station II shifted from 88 per- 

 cent downstream to about 58 percent cross reser- 

 voir. On May 2!>, tlie total discharge was reduced 

 further. A high jiercentage of the currents at the 

 downstream end and in the middle of the reser- 

 voir (stations I and II) were oriented upstream. 

 Downstream orientation of currents at station III 

 shifted sliglitly; this change may have resulted 

 from the subsequent filling action rather than fi-om 

 the reduced discharge. Currents remained well 

 oriented downstream at station III throughout the 

 l^e-riod because the reservoir is essentially river- 

 run in this area at this level. 



Fill-up unfh no spill. — Spilling ceased on 

 May 26, and filling of the reservoir resumed. Fig- 

 ure 12 shows the weekly average current velocities 

 and directions during fill-up from the minus 10.1- 

 to minus 4.9-m. level. Downstream currents de- 

 creased at all three stations from those recorded 

 during the previous period (minus 13.1 m.). Up- 

 stream currents were about as frequent as down- 

 stream currents at station I and II. Currents were 

 still downstream 95 percent of the time at station 

 III. Velocities ranged from zero at station I to 

 0.17 m.p.s. at station III. Velocity was zero 20 

 percent of the time at station I. 



Full pool with high spill. — The currents from 

 June 13 to 26, when the reservoir was full and a 

 large volume of water was being discharged over 

 the spillway, are described in figure 13. 



Currents were weak and downstream orientation 

 was larking during filling and at full pool im- 



320 



U.S. FISH AND WILDLIFE SERVICE 



