The Potomac River is high now, with all of the rain and run off.  So it'll be a while till Maryland and Virginia Chutes are back in play.  The best level at Virginia Chute to SUP is between 3.7 and 3.9.  That's when the wave is most glassy.  Learning to paddleboard on a hard board is a bit tricky, but the key is to keep the board pointed up river.  Here's a good video that shows learning to SUP paddleboard on the Potomac River in Potomac Maryland. http://www.youtube.com/watch?v=gYMnpeU4JS8