Delaware River Basin Conservation Reauthorization Act of 2023 This bill extends through FY2030 and revises the Delaware River Basin Restoration Program and the Delaware River Basin Restoration Grant Program. Specifically, the bill adds Maryland to the current list of basin states: Delaware, New Jersey, New York, and Pennsylvania. It also increases the federal cost share of a grant project that serves a small, rural, or disadvantaged community to 90% of the total cost of the project. However, the federal share may be increased to 100% of the project's total cost if the grant recipient is unable to pay, or would experience significant financial hardship if required to pay, the nonfederal share.