Md. Code, Local Gov't § 1-903

(a) On request of the Director of the Baltimore City Department of Public Works, the governing bodies of Anne Arundel County, Baltimore County, or Howard County shall restrict the use of water supplied by Baltimore City to any person or property located in the county: (1) to the same extent restrictions are imposed on the use of water by consumers in Baltimore City when there is a shortage of water; or (2) in limited areas when required due to deficiencies in the water distribution system serving the limited areas under conditions approved by the receiving county. (b) Before the imposition of a water restriction in a limited area of Anne Arundel County, Baltimore County, or Howard County, the Director of the Baltimore City Department of Public Works shall determine that the unrestricted use of water in all other areas of the county will have no detrimental effect on the restricted use area. (c) The governing bodies of Anne Arundel County, Baltimore County, and Howard County may pass any ordinance, resolution, rule, or regulation necessary to impose and enforce a water restriction under this subtitle and provide penalties for the violation of a restriction.