Nice job. I was just telling a friend this weekend that there are too many redundant color schemes among NHL teams, and brown seems like a color that (if presented well) could be a nice alternative as a dominant color scheme. Probably needs another accent color to avoid being too drab, though.
I agree with most that it's tough to see a Seattle team without the blue/green Seahawks colors. It also plays off of the Sharks and Canucks well, if that matters. But I like your logo and brown concept. Works great with the "Mammoth" theme. If I'm nitpicking, the poster above makes a great point regarding a "timeless" element, though I'm not sure many franchises have that going for them to make it a must. Over time, teams get re-branded or at the very least updated to keep with up the times. So I wouldn't sweat that too much. I think a little more detail could be nice, some minimal piping or striping in an additional accent color, also incorporated into the logo (something brighter, more colorful... not sure what would work). Overall I think these (browns) are a great idea, but a little too bland without that.