Water Quality 

 Standards 



I 



Co-Chairmen 

 R. L. Rulifson 

 R. Pine 



Based on a review of 20 papers dealing with the 

 biological effects of total dissolved gas supersatu- 

 ration on aquatic organisms, a group consisting 

 of Rob Rulifson, Ron Pine, Ed Quan, and Gene 

 Ralston representing EPA and state regulatory agen- 

 cies of Washington, Oregon and Idaho, respec- 

 tively, concluded that total dissolved gas super- 

 saturation is only one of many factors affecting 

 the fisheries of a river system where hydroelectric 

 projects are involved. During high flow years 

 supersaturation is a predominant factor causing 

 juvenile mortalities. Prototype tests with spillway 

 deflectors indicate they contribute minimally to 

 total losses; however, it is generally agreed that 

 the 110% level of total dissolved gas supersatura- 

 tion will probably never be reached. A level of 115% 

 supersaturation can be tolerated by juvenile sal- 

 monids considering the compensatory effects of 

 hydrostatic pressure and travel time in the river 

 system which will act to minimize mortality. There- 

 fore, the group concluded, "the total dissolved gas 

 standard in the Columbia and Snake Rivers could 

 be raised to 115% without causing significant 

 mortalities." 



Comments and discussion were solicited from 

 the round table participants and the resulting dis- 

 cussion raised several questions concerning the 

 appropriateness of the value 115% as a criterion to 

 provide reasonable protection of the most desir- 

 able water use and the riverine ecosystem as well 

 as attributes of a strong enforceable water quality 

 standard. 



There was no substantial opposition to the 

 recommendation of 115% as a criterion for protec- 

 tion of juvenile salmonids from direct lethal effects, 

 but it was suggested that the proposed value would 

 not adequately protect shallow water resident 

 organisms, in particular, invertebrate benthos 

 which are important food chain organisms, and 

 that 110% would provide reasonable protection 

 for them. In addition, levels below 115% may re- 

 sult in as yet undefined sublethal effects. On the 

 other hand, several suggested that even higher 

 levels would protect fishes in some locations given 

 sufficient hydrostatic pressure compensation, but 

 detailed knowledge of depth distribution of fishes 

 is not yet available. 



720 Round Table Discussion 



Provisions suggested for inclusion in an en- 

 forceable standard included: 



• Methodology to be employed in measuring 

 dissolved gas levels. This should include computa- 

 tions, sampling locations, and exclusion of water 

 vapor pressure from total gas tension calculations. 



• The area or extent of permitted levels of 

 excess dissolved gas tension should be defined, 

 including the zone allowed for mixing of power- 

 house and spillway waters. 



• Deviations from a basic enforcement level 

 might be permitted for a specified duration. 



• Temperature might be a factor involved in 

 a standard if studies of combined effects indicate 

 a synergistic effect of supersaturation and tem- 

 perature. 



• A flexible system might be developed which 

 would provide a separate enforcement level for 

 each site based on species composition, water 

 depth, and minimum practicable dissolved gas 

 levels. 



• Relevancy to regions beyond the Pacific 

 Northwest should be considered carefully as the 

 standard or criteria may become nationally 

 accepted. 



A general consensus was that a level of 115% 

 would protect salmonid fishes migrating through 

 the Columbia-Snake River systems but that a lower 

 level (110%) should be adopted as a criterion for 

 protection of shallow-water benthos. As an en- 

 forceable standard, 115% total gas saturation 

 appeared to be agreeable for the Columbia-Snake 

 River system as a realistically enforceable value 

 except during particularly high flow years. 



Rulifson: United States Environmental Protection Agency, Water 

 Quality Management Section, Seattle, Washington; and Pine: 

 Washington Department of Ecology, Olympia, Washington. 



