The NFPA 70E Standard details multiple levels of Hazard Risk Categories (HRC) [see table 1.1], also called Levels. The greater the risk: the higher the HRC. Arc Rating is the factor that indicates which HRC is necessary, and can be measured in either ATPV or EBT.
The optimal pH range for brook trout appears to be 6.5-8.0,with a tolerance range of 4.0-9.5.Brook trout occur in waters with a wide range of alkalinity and specificconductance, although high alkalinity and high specific conductance usuallyincrease brook trout production (Cooper and Scherer 1967).
Trout require dO2 of 3ppm to survive. When water reaches a temperature of 75 degrees fahrenheit 3ppm is the maximum dO2 the water can hold with out some form of turbulence to enhance gas exchange (oxygenation). At water temperatures above 75 f with no oxygenation of the water the trout will suffocate. The dO2 super saturation water temperature is 32 f. Water temperature also controls the troutâs metabolism. While very cold water can hold the maximum of dO2 it also slows the troutâs metabolism to the point of suspended animation ( a cryogenic effect ).