Limnological Study off Lower Columbia River, 1967-68 



by 



SHIRLEY M. CLARK and GEORGE R. SNYDER 

 Fishery Biologists 



Bureau of Commercial Fisheries, Biological Laboratory 

 Seattle, Washington 98102 



ABSTRACT 



Limnological data were collected from late July 1967 through December 1968 

 at seven sampling stations from above the mouth of the Willamette River to below 

 Puget Island. Items studied were: physical (water temperature, turbidity, con- 

 ductivity, and salinity), chemical (pH, dissolved oxygen, phosphate, silicate, calcium, 

 magnesium, and sodium), and biological (chlorophyll^ and zooplankton). Dissolved 

 oxygen was lower in 1967-68 than it had been in previous studies in 1954-55 and 1960; 

 water temperature was higher in 1967-68 than in the other two periods. 



INTRODUCTION 



The Columbia River has beenvery important 

 to the fishing industry of the Pacific Northwest 

 for more than 100 years. The limnological 

 characteristics of the lower river (from Bonne- 

 ville Dam to the estuary) are therefore of 

 interest to fishery agencies. Although these 

 characteristics are being altered by hydro- 

 logical projects, some of the effects of these 

 changes on stocks of fish are not known. A 

 few observations were made in the lower 

 river during 1954-55 (Sylvester, 1958), and an 

 extensive water quality study was made there 

 in 1960 (Sylvester and Carlson, 1961). BCF 

 (Bureau of Commercial Fisheries) made the 

 present limnological survey (July 1967-68) 

 following proposals that thermal nuclear 

 powerplants be installed along the lower river. 

 This report summarizes the data collected on 

 the physical (water temperature, turbidity, 

 conductivity, and salinity), chemical (pH, dis- 

 solved oxygen, phosphate, silicate, calcium, 

 magnesium, and sodium), and biological 

 (chlorophyll^ and zooplankton) conditions. 



STUDY AREA 



The authors selected seven stations from 

 just above the mouth of the Willamette River 

 to below Puget Island which is above the 

 present extent of salt-water intrusion. The 

 locations of the stations (fig. 1) were: 



Station 



River kilometer 



Station 



River kilometer 



1 166 



2 140 



3 135 



4 118 



5 106 



6 78 



7 54 



The lower Columbia River has four major 

 tributaries within the area studied. The Wil- 

 lamette River (the second largest tributary of 

 the Columbia River) enters just below station 

 1; Lewis River, at station 2; Kalama River, 

 between stations 3 and 4; and Cowlitz River, 

 between stations 4 and 5. Various creeks and 

 sloughs also flow into the lower Columbia 

 River. 



MATERIALS AND METHODS 



We collected physical, chemical, and bio- 

 logical data at 3-week intervals from November 

 through March and at 2-week intervals during 

 the rest of the year. Each survey required 2 

 days; stations 1 through 4 were sampled the 

 first day, and stations 5 through 7 the next. 

 Samples were taken from the middle of the 

 channel at all stations. 



Physical Data 



BCF personnel measured water tempera- 

 ture, turbidity, conductivity, and salinity at 

 the sampling site. Water temperature was 

 taken near the surface with a laboratory 

 thermometer. Turbidity was measured with 

 a Hach CR Low Range Turbidimeter, Model 

 1720, and recorded in JTU (Jackson Turbidity 



