According to an article at Science Daily, "Native, possibly giant, earthworm science in the Pacific Northwest is advancing with the discovery of two new specimens from opposite sides of the interior Columbia River basin. University of Idaho soil scientist Jodi Johnson-Maynard, an associate professor in the College of Agricultural and Life Sciences, said an earthworm that was most likely a giant Palouse earthworm was found in early March near Moscow [Idaho]."
I have trouble with the idea that worms of merely a foot long have trouble meeting the designation "giant" outside of Tremors
or Arrakis. Update: 05/06 17:44 GMT
: Correction: That's Moscow, Idaho, rather than Washington. Thanks to the alert reader who spotted this.