Exemptions from Discharge Prohibition.

1. (a) Section 25249.5 shall not apply to any discharge or release that takes place less than twenty months subsequent to the listing of the chemical in question on the list required to be published under subdivision (a) of Section 25249.8.

2. (b) Section 25249.5 shall not apply to any discharge or release that meets both of the following criteria:

   1. (1) The discharge or release will not cause any significant amount of the discharged or released chemical to enter any source of drinking water.

   2. (2) The discharge or release is in conformity with all other laws and with every applicable regulation, permit, requirement, and order.

      In any action brought to enforce Section 25249.5, the burden of showing that a discharge or release meets the criteria of this subdivision shall be on the defendant.