The regulatory definition of "waters of the United States" (WOTUS), a key term in the Clean Water Act (CWA) establishing the scope of federal jurisdiction, once again is changing. The most recent definition, promulgated in the Navigable Waters Protection Rule (NWPR) (2020), eliminated the coverage of many water bodies. Following the June 9, 2021 joint announcement (previously discussed on this blog)[1] by the US Environmental Protection Agency (EPA) and the Army Corps of Engineers (together Agencies) that they intended to revise the WOTUS rule, additional significant developments have occurred.