Delaware River Basin Conservation Reauthorization Act of 2023 This bill reauthorizes the Delaware River Basin Restoration Program and increases the federal cost share for certain grant projects. The bill also adds Maryland to the current list of basin states: Delaware, New Jersey, New York, and Pennsylvania. The bill specifically extends the Delaware River Basin Restoration Program through FY2030 and 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.