Try this webstie for some similar flies (http://bugguide.net/node/view/14950/tree). Look at the picture of the Rhagionidae since Athericidae was separated from this family if I remember correctly. I hope this helps. You might be interested to know that there are numerous superficially similar dipteran larva that are quite common in the northwest and it might make a really good searching pattern.
I will use a fly with a dubbed body (cream or cream with a little olive mixed in) and rib with either peacock herl or light olive thread. Works fairly well, but not the secret weapon (still looking for one…).
Although this isn’t a link, Rick Hafele wrote a complete article on Watersnipe Flies (or Snipe Flies, as I believe he referred to them) in his American Angler column last year. I believe it may have been the September 2005 issue. Would recommend you chase it down, as it was extremely informative.