Robyn,

You live a bit north and I live in New Jersey. Sometimes, I will find - in the pond store or lowes - a lily that is red, pink, etc. or maybe a lotus, dont remember, and it will list zone 5-6 like where we live. Since those lilies can live up north, can they thrive and be introduced to our respective state habitats? why haven't i seen these plants in my local ponds, lakes, after 15 of hiking, canoeing, fishing, etc

Those lilies are probably not native but can live in cold areas. I live at the edges of Zones 6 and 7. The zone listings for plants are all guesses really. If a waterlily says Zone 5-6, it will probably do fine in higher zones like 7 and 8 too. If those waterlilies were released into a local pond, etc., they potentially could spread but most likely wouldn't get there on their own. Many waterlilies are man made and originally came from native species or species from other countries. They may be descendants of native species but are no longer natives.