Small ones are almost always channels have not caught many small flathead but the 2 big ones were flathead. A friend of mine and I will drop a couple 8-10 in each year that are caught from the river. Good luck.
I dont know about a map but I can give directions. 69 hwy to D hwy going east into lawson. then turn to the north which is a left turn on North Raum. (north raum is the road right before you get tothe second railroad overpass) then follow n. raum across the wooden bridge then look to your right and you will see the lake. the first right will take you into the parking lot and boat ramp. No gas motors allowed in the water because it is water used for drinking water for lawson. so please dont poison my family haha. I took my son out on friday. a few bites but mainly the cold wind biting. good luck