(1) Except as provided in subsections (2) and (3), the limitation period for filing actions under this part is as follows:

    (a) For the recovery of response activity costs and natural resources damages pursuant to section 20126a(1)(a), (b), or (c), within 6 years of initiation of physical on-site construction activities for the remedial action selected or approved by the department at a facility, except as provided in subdivision (b).

    (b) For 1 or more subsequent actions for recovery of response activity costs pursuant to section 20126, at any time during the response activity, if commenced not later than 3 years after the date of completion of all response activity at the facility.

    (c) For civil fines under this part, within 3 years after discovery of the violation for which the civil fines are assessed.

    (2) For recovery of natural resources damages that accrued prior to July 1, 1991, the limitation period for filing actions under this part is July 1, 1994.

    (3) For recovery of response activity costs that were incurred prior to July 1, 1991, the limitation period for filing actions under this part is July 1, 1994.

    (4) Subsection (3) is curative and intended to clarify the original intent of the legislature and applies retroactively.