California Code, Public Resources Code - PRC § 3964

(a) Constructing a settling pond or ponds of sufficient size to permit the clarification of water used in the mining processes before the water is discharged into the stream.

(b) Mixing with the effluent from mining operations aluminum sulphate and lime, or an equivalent clarifying substance which will cause the solid material in the effluent to coagulate and thus avoid rendering the water in the stream unfit for domestic water supply purposes.