I believe the Washington Suburban Sanitary Commission (WSSC) do not permit the placement of brushpiles in any of their reservoirs. Give the WSSC office a call at (301) 774-9124. The reservoir is open until 31 Dec so they should still be in the office untill then.
The repairs on Rocky Gorge which started in 2007 was sopposed to be completed, and the pool raised Spring 08. In fact it was raised for two months and then drained again because the repairs were ineffective. No one can gurantee when it will be raised again but I''ll research it on the web to try and get more intel.
Let me know if you get the urge to fish some of our waters in Central MD and I'll take you out in my boat. You can reach me best on my cell at (410) 948-4145. Haven't learned a Fall or Winter pattern yet but fairly successfull in the Spring and Summer.
Good luck if you get out again this Winter and let me know how you did.
Charles Henderson
Laurel MD