Md. Code, Environment § 4–307

A person may not discharge raw sewage or any other waste into the Patuxent River, the Severn River, or any of their tributaries. For the purpose of this subtitle, oyster and clam shells, and materials used in the culture of marine life are not considered waste. Also a discharge from a sewage treatment plant operating pursuant to the provisions of § 4–303 of this subtitle is not considered waste for the purposes of this section.