The road to Manns Creek is accessible by car. I cant say for sure you'd be able to cross over the dam to access the southwest side but I'm fairly certain you'd be able to access the northeast side. You should be able to drive right down the boat dock but I cant promise you that. just a thin sheet of ice is all it would take to prevent it. From that side you'd be able to walk west to the creeks spillway where i would go personally for trout fishing. I know there are other fish present such as bass and perch as well but not a target fish for me at that reservoir.
The ice should be thick enough and i am strongly thinking about trying it myself NewYearsDay. Split between it and Lake Lowell at the moment.
Oh,Hi! And I must say,This is the most awesome Website!!