When was the Last hydro plant built in the us?

The last major hydroelectric plant built in the United States is the 2008-built North Anna Power Station's 3rd unit, which includes hydro capabilities, but it's important to note that many smaller hydro plants have been constructed since then. However, large-scale hydroelectric projects have seen a significant decline in new construction due to environmental concerns and regulatory challenges. Most new developments tend to focus on upgrading existing facilities rather than building new ones.