New Mexico Drought Preparedness Act of 2018 This bill directs the Bureau of Reclamation to carry out a water acquisition program in specified basins in New Mexico, under which Reclamation shall: (1) make acquisitions of water by lease or purchase of water rights or contractual entitlements from willing lessors or sellers, consistent with the Rio Grande Compact and applicable state water rights law; and (2) take other actions to enhance stream flow to benefit fish and wildlife (including endangered species), water quality, and river ecosystem restoration and to enhance stewardship and conservation of working land, water, and watersheds. Reclamation, in cooperation with the Middle Rio Grande Conservancy District, may provide funding and technical assistance for the installation of metering and measurement devices and the construction of check structures to: (1) ensure the conservation and efficient use of water by reducing actual consumptive use or by not increasing the use of water, and (2) improve the measurement and allocation of water. The National Academy of Sciences shall carry out a study on water and reservoir management and operation issues in specified basins. The bill authorizes financial assistance to be made available for eligible water projects to help western states and tribal governments address drought-related impacts to water supplies or any other immediate water-related crisis or conflict. The Omnibus Public Land Management Act of 2009 is amended to: (1) authorize the use of water management improvement grants to assist applicants in planning for or addressing the impacts of drought, (2) change to December 31, 2019, the reporting date on the implementation of recommended Rio Grande Pueblo irrigation infrastructure projects, and (3) reauthorize for FY2018-FY2026 the Rio Grande Pueblo irrigation infrastructure grant program.