How many active Mormon senators in washington?

Currently (October 2012), there are nine members of the Church of Jesus Christ of Latter-day Saints (the "Mormon" church) in the United States Congress. They are:

Dean Heller - R, California

Howard McKeon - R, California

Wally Herger - R, California

Jason Chaffetz - R, Utah

Jim Matheson - D, Utah

Rob Bishop - R, Utah

Mike Simpson - R, Idaho

Raul Labrador - R, Idaho

Jeff Flake - R, Arizona

There is also one member of the Community of Christ (Leonard Boswell - D, Iowa) in the current congress. The Community of Christ split with the Church of Jesus Christ of Latter-day Saints in the 1840's, but retains the same early history and similar beliefs such as Joseph Smith, the Book of Mormon, and continuing revelation.