could be attributed to gas bubble disease or gas 

 embolism. A study of the movement of these fish 

 indicated that many did not reach Ice Harbor 

 Dam.^ The destination or fate of these fish was 

 not determined. 



We have no positive evidence to indicate that the 

 high nitrogen saturation in the Columbia River in 

 1907 caused serious mortality of adult salmon, but 

 tlie possibility cannot be discounted. From the sur- 

 veys and searches made in 1967 it was obvious that 

 it would be difficult to detect a continuous low rate 

 of mortality in a river the size of the Columbia 

 even witli continuous surveillance. Various reports 

 of mortality were received from local residents, 

 but again it could not be established that fish had 

 died from gas l)ublile di-sease. 



SUMMARY AND CONCLUSIONS 



A seasonal cycle of supersaturation of dissolved 

 nitrogen occurs each year in the Columbia River. 

 Degi-ee of supersaturation varies with flow of wa- 

 ter over spillways of dams. levels are normal 

 (near 100-percent saturation) in the fall and win- 

 ter when little or no spilling takes place and high 

 (above 120 percent) in the spring and summer 

 when large volumes of water are being spilled. 

 Water plunging over spillways is the primary 

 cause of supersaturation in the Columbia River. 



Water supersaturated with nitrogen does not 

 equilibrate rapidly in reservoirs. Lack of circula- 

 tion and increases in surface Avater temperature 

 tend to slow the rate of equilibration. Saturation 

 of dissolved nitrogen in the Columbia River is 

 sufficiently high and occurs over a large area over 

 a sufficiently long time to be potentially dangerous 

 to salmon and steelhead trout. Observations of 

 juvenile salmon at Priest Rapids Dam indicate 

 tliat supersaturation of nitrogen otfers a definite 

 problem; further study is needed to determine its 

 extent. 



Field observations to determine the effect of 

 high levels of dissolved nitrogen on adult salmon 

 and steelliead trout were not conclusive. Some 



' PereentaKp of tng rPtiinis from fish Mihjpctfc] to tliesn coiidi- 

 tloiis was lUiont TiO iicn-iTit lownr than ri-turns from other Krmipx 

 passing over Icp Harbor Dam. (Verbal conimnnic'ation. Gerald 

 Monan, BCP Biolopioal Laboratory. Seattle. Wash.) 



sockeye salmon and steelhead trout were observed 

 with symptoms of gas bubble disease, but no 

 Chinook salmon had symptoms. A potential prob- 

 lem exists for adult salmon and trout migrating 

 from the Columbia River into the Snake River in 

 July and August. Fish equilibrated to supersatura- 

 tion of nitrogen from the Columbia River encoun- 

 ter an increase of 5° to 6° C. in temperature on 

 entering the Snake River. The tolerance of the 

 salmon to this temperature change under those 

 conditions is unknown. 



ACKNOWLEDGMENTS 



I thank Richard Westgard of the Washington 

 Department of Fisheries for providing photos of 

 external symptoms of gas bubble disease in adult 

 chinook salmon and for his advice on analytical 

 techniques for dissolved nitrogen. I also thank 

 Richard Krcma of the Bureau of Commercial 

 Fisheries, Pasco, Wash., for his help in conducting 

 the holding experiment at Priest Rapids Dam. 



LITERATURE CITED 



Brett, J. R. 



19.52. Temperature tolerance in young Pacific salmon, 

 genns Oncorhynchi/g. J. Fish. Res. Bd. Can. 9 : 265- 

 .323. 

 Harvey, H. H., and A. C. Cooper. 



1962. Origin and treatment of a supersaturated river 

 water. Int Pac. Salmon Fish. Comm., Progr. Rep. 

 9, 19 pp. [Processed.] 

 Harvey. H. H., and S. B. Smith. 



1962. Supersaturation of the water supply and oc- 

 currence of gas bubble disease at Cultus Lake trout 

 hatchery. Can. Fish Cult. .30: .39-17. 

 RucKER, R. R., and K. Hodgeboom. 



195.3. Observations on gas-bubble disease of fish. 

 Progr. Fish-Cult. 15 : 24-26. 

 SwiNNERTON, J. W., V. J. LiNNENBOM, and C. H. Cheek. 

 1962. Determination of dissolved gases in aqueous 

 solutions l)y gas chromatography. Anal. Chem. 

 34 ; 483-485. 

 Westgard. Richard L. 



1964. Physical and biological aspects of gas-bubble 

 disease in impounded adult chinook salmon at Mc- 

 Nary spawning channel. Trans. Amer. Fish. Soc. 

 93 : 306-309. 

 Woodbury, Lowell A. 



1942. A sudden mortality of fishes accompanying a 

 supersaturation of oxygen in Lake Waubesa, Wis- 

 consin. Trans. Amer. Fish. Soc. 71 : 112-117. 



SUPERSATURATION OF NITROGEN IN COLUMBIA RIVER 



11 



U. S. GOVERNMENT PRINTING OFFICE : 1969 O - 329-409 



