Can EPA draw conclusions or identify trends from this National Listing?
No. EPA’s role is to provide a central repository. Each State determines the scope and extent of monitoring, how to decide which waters should be placed under advisory, etc., thus the information is highly variable and difficult to draw conclusions or trends. Why have the number of advisories and the geographic extent of advisories steadily increased over the past 15 years? EPA believes that the increase in advisories is primarily due to increased sampling of previously untested waters by states and tribes and not necessarily due to increased levels or frequency of contamination. Why is there a dramatic increase in the number of river miles placed under an advisory during 2003? The increase in the number of river miles placed under advisory in 2003 is due to new statewide mercury river advisories in three states: Washington, Montana, and Wisconsin. Statewide advisories are issued as a precautionary measure when fish monitoring data indicate widespread contamination has been detected in
