Ala. Code § 9-6-14: Immunity from Tort Liability.

The engaging in and aiding, assisting and promoting the control, abatement and prevention of water, air and general environmental pollution by an authority is hereby declared to be a governmental function. The authority shall not be liable for any tort, whether negligent or willful, committed by any director, agent, servant or employee of the authority in the construction, maintenance or operation of any equipment, facilities, apparatus or systems in connection with activities in engaging in or aiding, assisting and promoting such pollution control, abatement or prevention.