On Sat, 06 Sep 2008 18:53:05 GMT, Tim Lysyk
wrote:

Thank you Dave. I also think small fish are a sign that a river is
healthy. We have been worried about Whirling Disease getting into our
area, so I am always happy to see small trout. As long as they are
present, all is well.

Some areas of New England (VT and NH) are dealing with Didymosphenia
geminata, aka didymo or rock snot, an invasive algae. It attacks the
stream rather than the fish, making aquatic life non-existent. There
are signs as you enter Maine warning about bringing in alien species
on boats/motors. If it reaches these pristine waters I fish, it will
be via the boots of a fly fisherman.

Dave