Recominenclation for Cold Waters: Because of the 

 large number of trout and salmon waters which have 

 been destroyed, or made marginal or nonproductive, 

 the remaining trout and salmon waters must be pro- 

 tected if this resource is to be preserved: 



(1) Inland trout streams, headwaters of salmon 

 streams, trout and salmon lakes and reservoirs, and the 

 hypolimnion of lakes and reservoirs containing sal- 

 monids should not be warmed. No heated effluents 

 should be discharged in the vicinity of spawning areas. 



For other types and reaches of cold-water streams, 

 reservoirs, and lakes, the following restrictions are 

 recommended. 



(2) During any month of the year, heat should not 

 be added to a stream in excess of the amount that will 

 raise the temperature of the water more than 5 F 

 (based on the minimum expected flow for that month). 

 In lakes and reservoirs, the temperature of the epi- 

 limnion should not be raised more than 3 F by the ad- 

 dition of heat of artificial origin. 



(3) The normal daily and seasonal temperature 

 fluctuations that existed before the addition of heat due 

 to other than natural causes should be maintained. 



(4) The recommended maximum temperatures that 

 are not to be exceeded for various species of cold water 

 fish are given in table III-l. 



Note. — For streams, total added heat (in BTU's) 

 might be specified as an allowable increase in tempera- 

 ture of the minimum daily flow expected for the month 

 or period in question. This would allow addition of a 

 constant amount of heat throughout the period. Ap- 

 proached in this way for all periods of the year, sea- 

 sonal variation would be maintained. For lakes the 

 situation is more complex and cannot be specified in 

 simple terms. 



TABLE III-l 



[Provisional maximum temperatures recommended as compati- 

 ble witli the well-being of various species of fish and 

 their associated biota] 



93 F: Growth of catfish, gar, white or yellow bass, 



spotted bass, buffalo, carpsucker, threadfin shad, 



and gizzard shad. 

 90 F: Growth of largemouth bass, drum, bluegill, and 



crappie. 

 84 F: Growth of pike, perch, walleye, smallmouth bass, 



and sauger. 

 80 F: Spawning and egg development of catfish, 



buffalo, threadfin shad, and gizzard shad. 

 75 F: Spawning and egg development of largemouth 



bass, white, yellow, and spotted bass. 

 68 F: Growth or migration routes of salmonids and for 



egg development of perch and smallmouth bass. 

 55 F: Spawning and egg development of salmon and 



trout (other than lake trout). 

 48 F: Spawning and egg development of lake trout, 



walleye, northern pike, sauger, and Atlantic 



salmon. 



Note. — Recommended temperatures for other species not 

 listed above, may be established if and when necessary in- 

 formation becomes available. 



Dissolved oxygen 



Oxygen requirements of aquatic life have been 

 extensively studied. Excellent survey papers are 



presented by Doudoroff (1957), Doudoroff and 

 Shumway (1967), Doudoroff and Warren 

 (1962), Ellis (1937), and Fry (1960). Much of 

 the work on temperature requirements also con- 

 siders oxygen and those bibliographies are equally 

 valuable. 



Most of the research concerning oxygen require- 

 ments for freshwater organisms deals with fish, but 

 since fish depend upon other aquatic species for 

 food and would not remain in an area with an in- 

 adequate food supply, it seems reasonable to as- 

 sume that a requirement for fish would serve also 

 for the rest of the community. The fish themselves 

 can be grouped into three categories according to 

 their temperature and oxygen requirements: 



(1) the cold-water fish (e.g., salmon and trout), 



(2) the warm-water game and pan fish (e.g., bass 

 and sunfish), and (3) the warm-water "coarse" 

 fish (e.g., carp and buffalo). The cold-water fish 

 seem to require higher oxygen concentrations than 

 the warm-water varieties. The reason is not known, 

 but it may be related to the fact that, for half 

 saturation, trout hemoglobin requires an oxygen 

 partial pressure three or four times that required 

 by carp hemoglobin under similar circumstances. 

 Warm-water game and pan fish seem to require a 

 higher concentration than the "coarse" fish, prob- 

 ably because the former are more active and 

 predatory. 



Relatively little of the research on the oxygen 

 requirements of fish in any of these three categories 

 is applicable to the problem of establishing oxygen 

 criteria because the endpoints have usually been 

 too crude. It is useless in the present context to 

 know how long an animal can resist death by as- 

 phyxiation at low dissolved oxygen concentrations; 

 we must know instead the oxygen concentration 

 that will permit an aquatic population to thrive. We 

 need data on the oxygen requirements for egg de- 

 velopment, for newly hatched larvae, for normal 

 growth and activity, and for completing all stages 

 of the reproductive cycle. It is only recently diat 

 experimental work has been tmdertaken on the 

 effects of oxygen concentration on these more 

 subtle endpoints. As yet, only a few species have 

 been studied. 



One of the first signs that a fish is being affected 

 by a reduction of dissolved oxygen (DO) concen- 

 tration is an increase in the rate at which it venti- 

 lates its gills, a process accomplished in part by an 

 increase in the frequency of the opercular move- 

 ments. The half dozen or so species (chiefly 

 warm-water game and pan fish) that have been 

 reported so far show a significant increase in fre- 

 quency as the DO concentration is reduced from 

 6 to 5 mg/1 (at about 72 F) and a greater increase 



43 



