The Environmental Monitoring and Assessment Program was created by EPA to develop the capability for tracking the changing conditions of our natural resources and to give environmental policy the advantages ofa sound scientific understanding of trends. Former EPA Administrators recognized early that contemporary monitoring programs could not even quantify simple unknowns like the number of lakes suffering from acid rain, let along determine if national control policies were benefiting these lakes. Today, adding to acidification impacts are truly complex problems such as determining the effects of climate change, of increases in ultraviolet light, toxic chemicals, eutrophication and critical habitat loss. Also today, the Government Performance and Results Act seeks to have agencies develop performance standards based on results rather than simply on levels of programmatic activities. The charge to EMAP of ecosystems is, therefore, the same today as it was a with respect to measuring the condition decade ago. We welcome the increasing urgency for sound scientific monitoring methods and data by efforts to protect and improve the environment. Systematic nationwide monitoring of natural resources is more than anyone program can accomplish, however. In an era of declining budgets, it is crucial that monitoring programs at all levels of government coordinate and share environmental data. EMAP resources are dwarfed by the more than $500 million spent on federal monitoring activities each year.