Effect of Gas Supersaturated Columbia River 



Water on the Survival of Juvenile 



Chinook and Coho Salmon 



THEODORE H. BLAHM, ROBERT J. McCONNELL, and GEORGE R. SNYDER' 



ABSTRACT 



The deleterious effect of high concentrations of dissolved gas on valuable stocks of 

 Columbia River salmon and trout has led pollution control agencies in the Pacific Northwest to 

 consider establishing standards for the amount of dissolved gas in the water. Research has been 

 done with salmonids to define the criteria upon which such standards should be based, but the 

 majority of these studies were carried out in shallow tanks (less than 1 m deep) where super- 

 saturated concentrations of gas had been artificially induced. This report discusses tests that 

 were performed at a field laboratory on the Columbia River. Juvenile chinook, Oncorhynchus 

 tshawytscha, and coho, O. kisutch, salmon were tested in deep and shallow tanks with river 

 water reflecting the prevailing (and fluctuating) concentrations of dissolved gases. Results in- 

 dicated that the water depth in a deep (3 m) test tank enhanced the survival of test fish com- 

 pared to shallow tanks ( -= 1 m). These tests support the hypothesis that test conditions in tanks 

 1 m deep are not representative of all river conditions that directly relate to mortality of juvenile 

 salmon and trout in the Columbia River. 



INTRODUCTION 



Early in 1972, Washington and Idaho set water 

 quality standards for maximum permissible levels of 

 dissolved elemental nitrogen at 110% of saturation for 

 the Columbia and Snake rivers; Oregon adopted 105% 

 as the maximum allowable. These preliminary stan- 

 dards were established without the benefit of ade- 

 quate biological information concerning the effects on 

 fish of dissolved nitrogen in combination with other 

 dissolved gases, water temperature, exposure time, 

 and swim depths. The Nitrogen Task Force (which 

 consists of, and is open to, Federal and State fisheries 

 and water quality agencies and to public and private 

 power companies) of the Columbia River Fisheries 

 Engineering Research Technical Advisory Committee 

 recommended studies that would provide information 

 on the gas supersaturation problem, its effects, and its 

 possible control. Although final approval of State 

 standards for saturation levels (which has not been 

 done to date) is the responsibility of the Federal En- 

 vironmental Protection Agency (EPA), many water- 

 use agencies have an interest in the development of 

 research programs that will provide data for use in the 

 final EPA evaluation. 



Concentration of gas in the Columbia River at 

 Prescott, Oreg., and throughout the entire length of 

 the river's estuary is dependent upon the amount of 

 water being released over the spillways of the upriver 



dams. Ebel (1969) reported supersaturated concen- 

 trations at estuarine sampling stations during periods 

 when spillrace flows were "high" at Bonneville Dam. 

 High concentrations in the upper estuary are signifi- 

 cant because valuable stocks of migrating Pacific 

 salmon, Oncorhynchus sp., and steelhead trout, 

 Salmo gairdneri, must pass through this area and 

 supersaturated concentrations sometimes cause gas- 

 bubble disease in salmon and trout. 



The National Marine Fisheries Service (NMFS) 

 and the U.S. Army Corps of Engineers initiated and 

 completed a cooperative research study during 1972 

 which was designed to provide information on the gas 

 supersaturation problem and its solution. The specific 

 purpose of this research was to estimate the mortality 

 of ocean-bound juvenile chinook, 0. tshawytscha, and 

 coho, 0. kisutch, salmon exposed to combinations of 

 nitrogen supersaturation and water temperature that 

 prevail in the Columbia River during the spring 

 freshet period when heavy spilling occurs at dams. 

 The work reported herein was performed under con- 

 tract number DAGW57-72-F0471, dated 4 April 1972, 

 between the Corps of Engineers and NMFS. This 

 report describes the results of that research study. 



METHODS 



Test Facility 



'Northwest Fisheries Center, National Marine Fisheries Service, 

 NOAA, 2725 Montlake Blvd. E., Seattle, WA 98112. 



The field station at which the tests were conducted 

 has been described in detail by Snyder et al. (1971). 



