Clean Water Allotment Modernization Act of 2023

This bill updates how federal clean water funding is distributed to states, tribes, and territories starting in 2024. It requires 0.1% of funds for "Buy American oversight," guarantees each state at least its 2023 funding level, and allocates additional funds based on state population. It also sets fixed percentages: 2% for Indian tribes and 1.5% for U.S. territories. For 2029 onward, funding will use a new formula based on a biennial "clean watersheds needs survey" that estimates infrastructure costs. The bill clarifies it does not affect existing infrastructure funds from the 2021 Infrastructure Investment and Jobs Act.