Section 401 certification and permit conditioning under the Clean Water Act is one of the most significant tools for states to influence federally permitted activities involving discharges into navigable waters. However, states are required to set conditions within one year or they forgo their ability to do so. In practice, the one-year review is difficult for states to meet and led to a common practice known as “withdraw and resubmit” in which states could reset the clock. But in Hoopa Valley Tribe v. Federal Energy Regulatory Comm’n, the D.C.