Idaho is taking an interesting approach to the problem...
Other than just doing the most obnoxious thing like other states have done, create a annual sticker and charge people for it, maybe print a few handouts where most will end up in the trash - as if that'll alone will fix anything other than give the state more money to waste. They are actually attempting to seriously combat the problem. Not that the NH lake host program isn't effective, inspecting trailers for hanging weeds won't stop the spread of those zebra/Asian clams.
http://www.idahoag.us/Categories/Env...ations_ALL.php
Interesting stats they post too. I highly doubt with the current measures NH has in place the spread of this stuff will be stopped. Pretty sad if you think about it.