History of the National Aquatic Resource Surveys

Clean Water Act (CWA) sections 104(a) and (b) collectively grant the EPA Administrator authority to investigate and report on water quality across the country. Clean Water Act (CWA) Section 305(b) also directs EPA and states to report on the condition of the nation’s waters. EPA analyzes information provided by states and tribes to report on water quality protection and restoration progress within each state or tribe. However, approaches to collecting and evaluating data vary from state to state, making it difficult to compare the information across states, on a nationwide basis, or over time.

In the early 2000s, a number of independent organizations, including the Government Accountability Office and the National Research Council, noted that EPA and the states did not have a uniform, consistent approach to answer key questions about water quality. In response, EPA, states, tribes, academics and other federal agencies began collaborating on a series of statistically based surveys called the National Aquatic Resource Surveys (NARS) to provide the public and decision-makers with improved, statistically-valid environmental information.

The Wadeable Streams Assessment (WSA), published in 2006, was the first report in this series, and the first nationally-consistent, statistically-valid study of the nation’s wadeable streams. It was followed by the first National Lakes Assessment (NLA 2007) as well as reports on coastal waters, wetlands and rivers and streams. Additional reports in this series are being prepared in a rotating basis, by waterbody type. 

NARS is based on the work of the EPA’s Environmental Monitoring and Assessment Program (EMAP). EMAP was a research program run by EPA’s Office of Research and Development (ORD) to develop the tools necessary to monitor and assess the status and trends of national ecological resources. EMAP collected field data from 1990 to 2006. Its goal was to develop the scientific understanding for translating environmental monitoring data from multiple spatial and temporal scales into assessments of current ecological condition and forecasts of future risks to our natural resources.

EMAP aimed to advance the science of ecological monitoring and ecological risk assessment, guide national monitoring with improved scientific understanding of ecosystem integrity and dynamics and demonstrate multi-agency monitoring through large regional projects. EMAP developed indicators to monitor the condition of ecological resources. It also investigated designs that addressed the acquisition, aggregation and analysis of multi-scale and multi-tier data.