WEATHER AND RIVER DISCHARGE DATA 



Headwater and tailwater elevations are 

 plotted on figures 1 and 2. Air temperatures 

 were taken twice daily by maximum and mini- 

 mum thermometer. A continuous record of 

 water temperatures was taken by thermograph 

 at the middle fish ladder. Daily records of 

 weather conditions and stream flows are shown 

 in tables 9-14. Average daily river discharge 

 data are plotted on figure 3. Maximum daily 

 discharge of 308,400 c.f.s. on June 17 was 

 18,900 c.f.s. less than the 1962 record high 

 discharge of 326,900 c.f.s. on June 5. Maximum 

 water temperature in 1963 of 65° F. occurred 

 August 6-10, 13, 16, and September 6-12. In 

 1962, maximum water temperature of 65° F. 

 occurred on July 28 and 29. 



ACTIVITIES AND OBSERVATIONS 



Wanapum Dam was completed in 1963, and 

 subsequent filling of the reservoir materially 

 altered the fish approach conditions to the 

 Rock Island Dam fishways. The ability of fish 

 to locate the fishways at Rock Island Dam, 

 or any other dam, depends in large part upon 

 the influence of fishway flows on existing 

 tailwater conditions. In 1963, modifications 

 were made to the middle and left ladders for 



fishway operation with the Wanapum Dam 

 reservoir encroachment. An evaluation study 

 of effects of Wanapum reservoir encroach- 

 ment on fish passage at Rock Island Dam is 

 to begin in 1964 as required by Federal Power 

 Commission order of October 24, 1962. 



Prior to 1963, changes in tailwater condi- 

 tions at Rock Island Dam were quite uniform 

 in their seasonal variations. Normally, highest 

 tailwater conditions occurred in May and June 

 with a reasonably consistent and steady low- 

 ering of the water level through August, Sep- 

 tember, and October. During the fish counting 

 season in 1962, highest tailwater elevation of 

 575.9 occurred in June; the lowest elevation, 

 548.4, on October 6. In 1963, the highest tail- 

 water elevation of 577.9 also occurred in 

 June; however, the lowest tailwater elevation 

 of 558.0 on May 14 (fig. 2) was 9.6 feet higher 

 than the lowest reading in 1962. Most pro- 

 nounced differences in tailwater conditions 

 at Rock Island Dam between 1962 and 1963 

 occurred from July 1 to the end of the counting 

 season in October. In 1962, tailwater elevation 

 on July 1 was 569.8; by October 6, it had 

 declined to 548.4. In 1963, tailwater elevation 

 on July 1 was 573.6, 3.8 feet higher than in 

 1962; the lowest recorded between that date 

 and the end of counting was 566.8 on Octo- 

 ber 18, or 18.4 feet higher than the previous 

 year. 



| I I I I I | I I I I I | 1 I I I I | I I I I I | 1 I I I I | I I I I I 



I i i i i i I I I i l I I I I 



^_ 



i I l l i l i 



3 10 15 20 25 



10 15 20 25 

 JUNE 



10 15 20 25 

 JULY 



10 6 20 25 

 AUGUST 



15 20 25 

 SEPTEMBER 



15 20 25 

 OCTOBER 



Figure 1. — Headwater elevations, Rock Island Dam, May 1 to October 30, 1963. 



19 



