Md. Code, Nat. Res. § 1-505

(a) An action pursuant to this subtitle shall be brought in the circuit court where the alleged condition, activity, or failure complained of is occurring, has occurred, or is likely to occur. (b) If the plaintiff is a person other than the State, an action does not lie under this subtitle unless the plaintiff, at least 30 days prior to the commencement of the action, has delivered a sufficient written notice of the alleged condition, activity, or failure to the agency of the State or its political subdivision responsible for initiating or instituting some official action as a result of the alleged condition, activity, or failure. A copy of the notice shall be simultaneously delivered to the Attorney General. (c) In addition to the copies which are to be served upon any person named as a defendant, a copy of the summons and bill of complaint and of any supporting papers and exhibits attached to it, including in all cases a certificate from the plaintiff under subsection (b) of this section of the date of the mailings, a copy of the mailed written notice and the signed certified mail receipts returned by the addressees, must be served upon the Attorney General, for purposes of notice and also to give him an opportunity to intervene. It is discretionary with the Attorney General and with each interested State agency or official represented by him whether to appear in the action but, upon application, at any time during the pendency of the action the Attorney General shall be permitted to intervene.