Administrative Rules of Montana
Department 17 - ENVIRONMENTAL QUALITY
Chapter 17.24 - RECLAMATION
Subchapter 17.24.18 - Rules and Regulations Governing the Montana Strip and Underground Mine Siting Act
Rule 17.24.1819 - WATER QUALITY: TREATMENT

(1) The operator shall by the treatment of all water leaving the mine site location prevent the drainage into the waters of the state drainage from any source, the pH of which is less than 6.0 or greater than 9.0, or which contains a concentration of iron in excess of 7 milligrams per liter (mg/l). The discharge must register positive net alkalinity (total alkalinity must exceed the total acidity) and the turbidity shall not exceed 100 Jackson candle units (JCU). The department may modify above requirements if special problems occur.

(2) The maximum total allowable increase to naturally occurring stream turbidity is 10 JCU except that 4 hours following a major precipitation event, the discharge shall not contain suspended sediments in excess of 500 JCU above normal and not over 100 JCU above normal 24 hours thereafter. All analyses are to be defined and performed according to the standard methods for the examination of water and wastewater, unless otherwise specified in writing by the department. If the above standards of this rule are in conflict with federal and/or other Montana state agencies the more stringent regulations will apply.