US EPA suggests as a guideline that a river sustaining salmonid populations should not have 7DADM temperatures over 18°C to avoid impairment of salmon health. Similarly, migratory portions of the river should not exceed Maximum Weekly Maximum Temperatures of 20°C and temperatures greater than 22°C will cause broad mortality (US EPA 2003). For core rearing areas in mid-to-upper parts of the river basin, a maximum of 16°C may be appropriate. Experimental studies indicate that spawning temperatures up to 16.5°C do not have deleterious effects on juvenile salmon, but mortality increases markedly after that point (Geist et al. 2006). These temperature guidelines, along with additional information from Brett et al. (1982), were used to convert monthly maximum 7DADM into a 0-100 scale. A score of 100 is equivalent to the EPA’s stated protective criteria of 18°C 7DADM for secondary foraging/rearing areas. A score of 0 will be equivalent to an instantaneous 7DADM temperature of 25°C, the lethal point for juvenile Chinook salmon. Intermediate scores were scaled using an adaptation of the Brett et al. (1982) growth curve (Figure 1). Only the right side of the curve was used; temperatures below the EPA protective criterion were still scored as 100. Brett et al. (1982) estimate that natural populations of Chinook feed at roughly 60% of saturation (or R=0.6, the lowest growth curve). Because of daily temperature fluctuation, 7DADM temperatures are equivalent to constant laboratory temperatures roughly 1-2°C colder (US EPA 2003). The scaling curve is shown in Figure 2. The scaling curve does not exactly match the growth curve, due to the temperature thresholds for 0 (25°C) and 100 (18°C). Temperatures for the growth curve were adjusted upward by 1.5°C to adjust for the use of 7DADM measurements. These scores are most applicable to summer maximum temperatures.