20 



l-< 

 <^ 

 W -I 



^1 



cQ 



o 



CO 



O E Q£ 

 0)0 fO 



I 



iE 



140 



'120 



Hl30 



z 



UJ 



o 



UJ 



a. 

 -110 



° 100 



JUNE 6 



— • AUGUST 2 



- ^ MAY I 



5 90- 



I- 

 < 

 <^ 80 



70- 



60- 



OCTOBER 3 



POTENTIALLY DANGEROUS 

 SATURATION LEVEL 



80 160 240 320 400 480 



DISTANCE FROM MOUTH OF RIVER (KM.) 



560 



640 



Figure 4. — Saturation values of dissolved nitrogen in samples of Columbia River water taken from Long- 

 vievc. Wash., to Priest Uapids Dam, May 1, June 6, August 2, and October 3, 1967. (Values shown are 

 the averages of the surface and 10-m. sample at each location.) 



Saturation in May 1967 (102-115 percent) was 

 considerably lower than in May 1966 (110-133 

 percent) because spillway releases in 1967 were not 

 significant on tlie main Columbia until late May. 

 By mid-Jmie 1967, however, extremely high spill- 

 way releases brought even higher saturations than 

 were recorded in 1966. 



In 1966-67 the saturation of dissolved nitrogen 

 over a large area of the river was sufficiently high 

 and of sufficient duration (middle to late May 

 through mid-August) to be a potential danger to 

 migrating juvenile and adult salmon and trout. 

 Experiments by Westgard (1964) showed that 

 adult chinook salmon held in water with concen- 

 trations of dissolved nitrogen at 116 percent sat- 

 uration de\^lopecl definite symptoms of gas l)ul)ble 

 disease. Harvey and Smith (1962) indicated that 

 saturation as low as 108 jaercent produced gas bub- 

 ble disease in fingerlings at Cultus Lake Trout 

 Hatchery. These values were much lower than 

 those recorded in the Columbia River. The fish 

 were held in shallow ponds or raceways, however, 



whereas fish in the Columbia Eiver are usually able 

 to move to greater (compensating) depths, except 

 when they are ascending fish ways. The ability of 

 fish to seek compensating depths must be taken into 

 account in the assessment of the effect of high sat- 

 uration of nitrogen in the Columbia River. 



EFFECT OF SUPERSATURATION OF 



DISSOLVED NITROGEN ON SALMON 



IN THE COLUMBIA RIVER 



Studies of suijersaturation of nitrogen in 1967 

 were made in conjunction with tagging studies 

 designed to determine the cause of loss of adult 

 fish during their migration from Bonneville to Ice 

 Harbor and Priest Rapids Dams.^ The primary 

 purpose in 1967 was to determine the effect of dis- 

 solved nitrogen on juvenile and adult salmon and 

 st«elhead known to be in the river when concen- 

 trations of dissolved nitrogen were high. 



'■' Tagging stud.v in progress by Bureau of Commercial Fisheries, 

 Seattle, Wash. — James H. Johnson, Program Leader. 



8 



U.S. FISH AND WILDLIFE SERVICE 



