Monitors the quality of the air; drinking, surface, and ground water; ecosystem status; and the use and release of toxic or hazardous substances. EPA conducts research and studies to provide baseline data and to evaluate and support environmental monitoring systems. Projects include state and local programs to report ambient air quality levels of pollutants and estimated emissions of pollutants from major stationary sources, and projection of future air quality levels through models that take into account past air quality monitoring data and emissions data. Other statistical activities develop methods to document the distribution and determinants of exposure to pollutants experienced by the U.S. population, and methods to measure exposure to and the potential effects of pollutants on human health and ecosystems.

Collects remotely-sensed data to improve our understanding of and contribute to improved predictive capability for climate, weather, and natural hazards. Research and satellite programs study atmospheric chemistry and ozone, ocean surface height and winds as well as biological productivity, precipitation and the global hydrological cycle, the global carbon cycle and land surface and vegetation and ecosystems, and solid earth geophysics. Data assimilation is used to provide accurate and consistent estimates of the global distribution of a broad range of environmental parameters and to initialize forecast models.

Gathers worldwide environmental data about the oceans, earth, air, space, and sun and their interactions to describe and predict the state of the physical environment. In fulfillment of this mission, the National Environmental Satellite, Data, and Information Service (NESDIS) maintains national data centers that preserve and disseminate the agency's climatic, oceanographic, and geophysical data and selected environmental information collected by other agencies.

Collects and maintains data on the quality, availability, and use of the Nation's water, including streamflow data for flood forecasting; streamflow data that help determine water allocations for agriculture, industry, and domestic supply; streamflow data for hydropower, navigation, instream habitat, engineering design of bridges and flood control structures, and other purposes; water quality data used by EPA and the states for compliance with the Clean Water Act and other regulations; and data on the availability and quality of ground water that help determine sustainability of supplies for the future.