7.1.1 marine water
A criterion of 2.3 µg/L of total recoverable silver, not to be exceeded at any time, was set by USEPA in 1980a. In 1976, their criterion was 0.01 of the 96 hour LC50 of a resident sensitive species.
7.1.2 fresh water
Concentrations of total silver in an unfiltered sample should not exceed 0.1 µg/L to protect aquatic life (IJC 1982, Taylor et al. 1980, Ontario 1979 and 1984, CCME 1987). A provisional or preliminary criterion of 0.1 µg/L was set by Manitoba in 1983. The USEPA set ambient water quality criteria of 50 µg/L in 1980a and the water quality criteria for 6 US states was reported as 50 µg/L by CELDS in 1989. In 1980a the USEPA set hardness dependent levels of 1.2 µg/L at 200 mg/L hardness, 4.1 µg/L at 400 mg/L hardness and 13 µg/L at 800 mg/L hardness. These 1980a USEPA criteria, which are not to be exceeded at any time, are derived from the equation: e(1.72 [ln(hardness)] - 6.52).