Md. Code, Environment § 1–904

(a) (1) Subject to paragraph (2) of this subsection, a person that meets the threshold standing requirements under federal law has the unconditional right and authority to intervene in a civil action brought by the Secretary under:

(i) Title 5, Subtitle 9 of this article; or

(ii) Title 9, Subtitle 3 of this article.

(2) A person shall exercise the right to intervene under paragraph (1) of this subsection in accordance with the applicable practices, procedures, and laws in the State.

(3) A person that has standing to intervene under paragraph (1) of this subsection has the same rights as an interested person or aggrieved party under the federal Clean Water Act.

(b) The State may intervene as a matter of right at any time in any proceeding brought under this subtitle.