The "New Mexico Land Grant-Mercedes Historical or Traditional Use Cooperation and Coordination Act" seeks to enhance collaboration between Federal agencies and New Mexico's qualified land grant-mercedes concerning their historical or traditional uses of Federal public land. This legislation defines "historical or traditional use" to include noncommercial activities such as water use, gathering herbs, wood, or flora, grazing, subsistence hunting or fishing, and maintaining existing monuments or cemeteries. A central provision requires the Secretary of Agriculture or Interior to enter into a Memorandum of Understanding (MOU) with the New Mexico Land Grant Council within two years. These MOUs will outline permit requirements, administrative procedures, and potential fee reductions or waivers for land grant-merced community users. They will also address the permissible use of vehicles, equipment, and nonnative materials for these traditional activities. Furthermore, the MOUs must cover authorization for routine maintenance and minor improvements of infrastructure related to historical uses, and may describe processes for major improvements. The bill also mandates that Federal land use plans consider and evaluate the impact of other uses on these historical or traditional practices. Importantly, the Act clarifies that it does not modify existing Indian treaty rights, state authority over water or game, or create new implicit or explicit rights to Federal land use.