The public shall be notified by the bureau of a proposed action (in active voice)

The bureau shall notify the public of a proposed action.

Explanation:

The original sentence is in passive voice: the public is not performing the action but receiving it. The passive voice uses the verb 'to be' + the past participle of the main verb: "shall be" + "notified".

The focus of a passive voice sentence is on the object and not on the subject: the public is the object; they will receive the act of the subject which is the bureau.

To change the passive voice to active voice, place the person who performs the action in the first part and change the tense of the verb to active form.

The subject that performs the action is the bureau. Thus, the active voice is:

The bureau shall notify the public of a proposed action.

Now, the focus of the sentence is on who performed the action; thus, this is the active voice.