The bill establishes new selenium standards specifically for Lake Koocanusa and the Kootenai River mainstem, amending existing water quality regulations. It mandates that the Department of Environmental Quality (DEQ) amend ARM 17.30.602 to remove the definition of "steady state" and sets specific water column standards for total dissolved selenium. For Lake Koocanusa, the standard is set at a maximum of 1.5 micrograms per liter, while for the Kootenai River mainstem, it is 3.1 micrograms per liter, both calculated as a 30-day average and not to be exceeded more than once every three years.

Additionally, the bill repeals ARM 17.30.632 and includes provisions for notifying tribal governments about the new regulations. It specifies that the effective date of the new standards will be contingent upon the DEQ certifying that the U.S. Environmental Protection Agency has approved the change to the selenium standard. The DEQ is required to submit this certification within 60 days of the occurrence of the contingency.

Statutes affected:
HB0473_1.pdf: 75-5-310
HB0473_2.pdf: 75-5-310
Amended: 75-5-310
Introduced: 75-5-310