That's good to know. Actually, it was really nifty driving along Clara Barton Parkway and Canal Road on the way to work this morning. The light snow on top of the new leaves and blossoms was really beautiful.
Ok, to get to White's Ferry: First you need to get to Route 28, which you've most likely been on if you've gone to Riley's Lock. Instead of turning off towards Riley's, continue NW on Route 28 for another few miles. You'll cross over a wide bridge (Seneca Creek). Just after that, bear left onto Route 107/White's Ferry Rd. Stay on that aaaaaall the way through Poolesville and out to the Ferry (roughly 11 miles from where you turned off of Route 28). The road ends at the ferry, so there's no chance of missing it. The large dirt parking lot is to the right.
Velobambina, if you're able to join us, you may want to head out to Leesburg and take the ferry across.
The Ferry convenience store doesn't open until May, so either bring all the snacks you need or stop in Poolesville to stock up. The bathrooms at White's Ferry probably also won't be open yet, but there are two porta-johns maintained by the NPS.