ah - tech support fixed the problem with the race thread
I did actually poke around and found a site which has Potomac River water temp info - and as of yesterday it said 82 degrees at Little Falls (just upriver from the race site). That site is: http://waterdata.usgs.gov/dc/nwis/uv?cb_00010=on&cb_00010=on&cb_00010=on&format=html&period=1&site_no=01646500
Like Eagleman last weekend, this one could very well have wetsuits disallowed. On the bright side, at least there won't be jellyfish :-)