The first time he takes the bench later this month, new Supreme Court Justice Samuel Alito Jr. will face a baptism — not by fire but by water.

Three cases challenging the scope of the Clean Water Act will be argued Feb. 21, testing themes of federalism and commerce clause power that were much at issue during Alito’s confirmation hearings. The cases have environmentalists worried about how Alito and Chief Justice John Roberts Jr. will ultimately come down.