Did the Middle Patuxent from 108 to Kindler Rd about 10 years ago. There are several "strainers" (total blockages of downed trees and sticks) that we had to get out and carry the kayak around. Mostly in the Middle Patuxent Envinormental Area. Under the 29 bridge there is about a 2-3 ft concrete dropoff which we decided to get out and portage around also.

It's pretty shallow year round, there were a few spots where we bottomed out bad enough at least one of us had to get out and pull/push.

But it was a pleasant float, the water is very calm, and the scenery is pretty good!