Kavanaugh, J., concurring in judgment
22307; 88 Fed. Reg. 3095, 3118. Similarly, artificial barriers such as dikes and levees typically do not block all water flow, 85 Fed. Reg. 22312; 88 Fed. Reg. 3076, and those artificial structures were often built to control the surface water connection between the wetland and the water. 85 Fed. Reg. 22315; 88 Fed. Reg. 3118. The scientific evidence overwhelmingly demonstrates that wetlands separated from covered waters by those kinds of berms or barriers, for example, still play an important role in protecting neighboring and downstream waters, including by filtering pollutants, storing water, and providing flood control. See 88 Fed. Reg. 3118; 33 CFR §320.4(b)(2) (2022); see also United States v. Riverside Bayview Homes, Inc., 474 U. S. 121, 134 (1985). In short, those adjacent wetlands may affect downstream water quality and flood control in many of the same ways that adjoining wetlands can.
The Court’s erroneous test not only will create real-world consequences for the waters of the United States, but also is sufficiently novel and vague (at least as a single standalone test) that it may create regulatory uncertainty for the Federal Government, the States, and regulated parties. As the Federal Government suggests, the continuous surface connection test raises “a host of thorny questions” and will lead to “potentially arbitrary results.” Brief for Respondents 29. For example, how difficult does it have to be to discern the boundary between a water and a wetland for the wetland to be covered by the Clean Water Act? How does that test apply to the many kinds of wetlands that typically do not have a surface water connection to a covered water year-round—for example, wetlands and waters that are connected for much of the year but not in the summer when they dry up to some extent? How “temporary” do “interruptions in surface connection” have to be for wetlands to still be covered? Ante, at 21. How does the test operate in areas where
