Dock help

Hello all. I fish a covered dock throughout most of the year. I have had decent success except for the past 3 months or so. Its like the crappie have just packed up and gone. I'll only catch 3-5 in about 3 hrs of sitting there while in the spring I'll catch 15-20 easily. The depth of water ranges from 18-30 ft and has a few pvc trees, some oak brush and a couple of pallet stake beds with vinyl hose attached to them.
The dock is not particularly close to the main creek channel (~200-300 yards out) but the depth range seems spot on. Is it just the time of year or do I need more structure? Small dynamite charge? Underwater neon sign?

I normally fish a standard minnow rig. #1 or #2 gold hook about 1ft below a split shot, minnow hooked through the back or head, 4 or 6# clear mono. I usually only get to fish in the evenings but when I do get a morning to go, the results are no different.

Any help would be appreciated.

Maybe over fished or no baitfish around. One thing you might try is to attract more baitfish by feeding them. Get some dry dog food and put in into a fine mess wire container so larger fish and turtles can't get to it and sink or suspend it to whatever depth you want. If you feed them they will come. Just something to try. Hope this helps.

Understand that most people want cover that is snag free and tends to hold slab sized fish, but finer cover tends to attract minnows and smaller prey. Might suggest dropping 4-6 8- 10` cedars or Christmas trees in lines on both sides of the dock, assuming the older cover is actually under it. If necessary, use a boat to get them 15-20` away; can tie or secure the blocks tightly flat against the trunk so they will eventually lay over. The more cover in the area near and under the dock the greater the area affected and the more varied the biomass there; put in in lines helps create avenues of travel and covers the seasonal depth preferences of more than a few types of fish. The bad thing is of course the fish will have more cover to attempt to dive into after being hooked; a trade off...