A 2006 opinion by US Supreme Court Justice Anthony Kennedy is still reverberating throughout environment regulation circles, having triggered a decade of fevered debate over how to determine which bodies of water are protected by the Clean Water Act of 1972. By positing that a waterway had to be part of a "significant nexus" with a river or wetland to be covered under the act, Kennedy's decision sparked dozens of lawsuits. Ultimately, the Environmental Protection Agency (EPA) and Army Corp of Engineers were charged with mapping flows of pollutants through waterways. The resulting 408-page report outlines a "legal shield" that the Obama administration hopes will protect what they've dubbed the Clean Water Rule from incursions by farm groups, developers and others. A discusson of legal and regulatory actions taken since the 2006 decision, as well as an overview of its expected future, can be found in a Politico article here.