John,
I've never fished the actual Bush river for Crappies, but there are a few in Gray's Run (the bridge at Rt40). You can fish there right now from shore. The yellow perch aren't there yet but will be in the next week or 2.
You would be much better off to go west on Rt40 a few miles to Joppatowne. Nice public ramp there. If you are in the military you can also launch at the ramp near the deer shack in the Edgewood area. It puts you in the Gunpowder just inside Maxwell point. You would only be a couple of miles by water from the Joppatowne canals.