Correction (June 01, 2001)

There was a mistake in the “Environmental Controls” section of our recent article about the Red Dog mine (CMJ, April 2001, p.21). The treated water quality numbers are quoted as 70 mg/L Zn, 1-2 mg/L Pb and <1 mg/L Cd. The numbers are correct, but the units should be g/L (i.e., ppb), not mg/L (ppm).