I know a lot about fishing the Purgatoire upstream from Trinidad Lake, but I have never paddled any of it. It is very narrow and shallow in a lot of places. I read something about a section below Trinidad after doing a Google search. I know the river goes through a deep canyon out on the plains and evidently it has some good whitewater there.
I was just in Trinidad in early May 2011. At first the tailwater below Trinidad Lake was very shallow. Then they started letting water out of the dam. When I left the stream was bank full and flowing fast.
I would hesitate to try to paddle the stream below the dam and beyond because of how narrow it is. I would think you could get knocked over real easily by overhanging limbs and downed trees. A lot of fences go clear across the river as well. Sounds risky and tedious to me.
If you want to know about fishing the river, give me an email.