Comparison of beginning emergence dates to first catch dates of juvenile fall chinook and chum below Bonneville Dam,  
1999-2003.a
Chinook Chum
1999 2000 2001 2002 2003 1999 2000 2001 2002 2003
estimated beginning 
emergence date: March 2 Jan. 26 Feb. 8 Jan. 25 Jan. 20 March 29 Feb. 3 Feb. 15 Jan. 29 Jan. 27
water temp. (oF)
(Bonneville Dam): 40 39 37 39 42 44 37 37 39 42
                                       
first catch date: March 2 Jan. 26 Feb. 22 Jan. 22 Jan. 24 March 12 Feb. 22 Feb. 8 Feb. 19 Jan. 31
water temp. (oF)
(Bonneville Dam): 40 39 37 42 42 41 39 37 39 39
number caught
on first catch date: 1 27 2 14 73 2 1 2 1 2
mean length (mm): 36 44 47 39 45 39 36 38 36 35
Bonneville Dam
tailwater elevation (ft)
at first catch date:b 21.8 18.0 11.7 14.5 11.7 19.5 14.4 11.7 28.7 16.3
Bonneville Dam
discharge (KCFS)
at first catch date:b 238 203 128 160 119 241 149 122 139 151
number of weeks
between est. date of
emergence and date
of first catch: 0 0 +2 0 +0.5 -2.5 +3 -1 +2 +0.5
                                         
a Chinook are early spawning stock (tules).
b USACE 12:00 am reading.