More recently, the English Water Research Centre summarized and commented on 

 the development of European water quality standards designed to protect fish 

 life (with some species differentiation) (Water Research Centre 1979). This 

 report emphasized that the continuing gaps in our knowledge of fish response to 

 pollution made guidelines more desirable than inflexible requirements. 



Table 1. — Logical Statements Translating Ambient Water Quality Measures 

 into Three Mutually Exclusive Fishery Groups According to 

 Water Quality 



Rule No. 

 1. 

 2. 

 3. 

 4. 

 5. 

 6. 



7. 



8. 



If pH is above 10.0 then 



If pH is below 5.0 then 



If DO is below 2.0 mg/1 then 



If Temp, is above 35°C then 



If summer streamflow is zero then 



Water Class 

 No Fishery Supportable 

 No Fishery Supportable 

 No Fishery Supportable 

 No Fishery Supportable 

 No Fishery Supportable 



If DO is between 2.0 mg/1 and 

 3.0 mg/1 then 



If DO is above 3.0 mg/1 and 

 Temp, if above 32 °C then 



If DO is above 3.0 mg/1 and 



TSS is greater than 100 mg/1 then 



Rough Fish 



Rough Fish 



Rough Fish 



9. 



If DO is greater than 3.0 mg/1, 

 Temp, is between 18°C, and TSS is 

 below 100 mg/1 then 



Warmwater Gamefish/ 

 Panfish 



10. 



If DO is greater than 5.0 mg/1, 

 Temp, is less than 18°C, and TSS 

 is less than 100 mg/1 then 



Co Id water Gamefish 



Key: 



DO: 90-day average summer dissolved oxygen concentration 



Temp.: 90-day average summer temperature 



TSS: Annual average total suspended solids concentration 



43 



