Conductivity and Salinity 



Conductivity and salinity were usually higher 

 at station 5 than at any other station (fig. 12). 

 This difference was attributed to the Cowlitz 

 River, which flows into the Columbia just above 

 station 5 and receives saline water from 

 underground caverns. Conductivity and salinity 

 at station 5 tended to be higher in winter than 

 in summer. The same tendency, though less 

 pronounced, was also present at the other 

 stations. The range in surface conductivityfor 

 station 5 was 220 to 1,100 yumhos/cm,; the 

 average for the other six stations was 160 to 

 350 >imhos/cm. Surface salinity at station 5 

 was 0.08 to 0.96 % (parts per thousand); the 

 average for the other six stations rangedfrom 



0.1 to 0.3 %o. Though conductivity and salinity 

 were measured at 3-m. intervals, only sur- 

 face values are given here because the water 

 mass was usually vertically homogeneous 

 at all stations at all times of year. 



PH 



Values of pH decreased from station 1 down- 

 river to station 7 and varied seasonally (figs. 

 3 and 7). The highest pH recorded in the sum- 

 mer of 1967 was 8.5 in late July and August. 

 After the spring bloom of phytoplankton in late 

 April 1968, the pH reached 7.9 but remained 

 low the rest of the summer, never exceeding 

 7.7. The lowest pH recorded was 7.3 in June 

 1968. 



CONDUCTIVITY 



stations \ 



I, 2, 3,4,6 and 7 ^-^ ^-* 4 



s „- / Mean of 

 Stations 



1,2, 3,4,6 and 7 ' ■• 



OCT. 'NOV. 'DEC. 'JAN. ' FEB. 1 MAR. ' APR. ' MAY 'jUN. ' JUL. 1 AUG. 'SEP. ' OCT. ' NOV 1 DEC. 

 1967 1968 



--Average conductivity (a) and salinity (b) at sampling station 5 and stations 1, 2, 3, 4, 6, and 7, October 1967 



through December 1968. 



