In what must be a flub, U.S. Interior Secretary Gale Norton yesterday named a toxic dump in Fresno, Calif., as a national historic landmark. Officials weren’t sure how the landfill was nominated for the prestigious designation. The 145-acre Fresno Municipal Sanitary Landfill is also listed as a Superfund site, with cleanup costs estimated at $38 million. City councilperson Brian Calhoun’s response upon hearing about the designation: “Are you kidding?”