The decisions in Solid Waste Agency of Northern Cook County v. U.S. Army Corps of Engineers, 531 U.S. 159 (2001) (SWANCC) and Rapanos v. United States, 547 U.S. ___(2006), deviated from the more broad interpretations of congressional intent granted by the court in past assessments of the constitutionality of environmental regulation under the Commerce Clause of the United States Constitution. These landmark Clean Water Act decisions forever altered the landscape of federal water regulation and set forth a new test for federal jurisdiction over wetlands. The SWANCC decision narrowed the scope of federal wetland protection. The case established that the federal government cannot assert jurisdiction over isolated wetlands that do not possess a “significant nexus” to traditionally navigable waters. Rapanos further defined this “significant nexus” by outlining the criteria that must be met in order to assert federal jurisdiction: the wetlands in question must “significantly affect” the chemical, physical, or biological integrity of navigable waters. The impact of these cases on federal wetland protection depends on the scientific criteria and impact thresholds federal agencies set forth when they issue a rulemaking in response to these decisions.