Comprehensive National Mercury Monitoring Act

Comprehensive National Mercury Monitoring Act - Directs the Administrator of the Environmental Protection Agency (EPA) to establish a long-term national-scale mercury monitoring program that monitors long-term changes in: (1) mercury levels in air and watersheds, and (2) mercury and methylmercury levels in water and soil and in aquatic and terrestrial organisms.

Requires the Administrator to: (1) select multiple monitoring sites representing different U.S. ecoregions that include national parks, wildlife refuges, national estuarine reserves, and other sensitive ecological areas in which substantive changes are expected from reductions in domestic mercury emissions; (2) establish and publish standardized measurement protocols for the program; and (3) establish a centralized database for environmental mercury data.

Establishes a Mercury Monitoring Advisory Committee to advise the Administrator on the establishment, site selection, measurement, recording protocols, data integration, standardization protocols, reporting, funding, and operation of the program.

Requires the Administrator to report on the program every two years and include, every four years, an assessment of the reduction in mercury deposition rates that must be achieved in order to prevent adverse human and ecological effects.