I have a 7-8 acre pond. 8-10' in the middle. Most coves are 4-5'. I've added this year alone, 6 bottom diffusers, rock piles, brush lines, hundreds of bog flowers, and floating islands. Its addicting and i want more! With the water being a solid 2' low from the summer heat/drought. I've been making improvements where I can. I've read a lot about how to build and what to put in bluegill beds but I have not found much information on where to put them. I understand the they need to be in 6"-2' of water. Will they use them anywhere in my pond or do they need to meet other criteria as well? shade, wind breaks, etc.. I'll add a picture in the comments of the pond, where my diffusers are and where I "plan" to put my first bed. Thanks for your help!
With your fluctuating water table I would just put 4" thick pea gravel in 4 different areas to start. I would put it on each of the compass points, in water levels (at full pool) from 1' deep to 5' deep. The BG will tell you what side of the pond they prefer and you can expand the bedding areas from that information.
Initially I'd only make an area about 10' wide.
To prolong the life of the pea gravel in the pond, I recommend putting geotextile fabric under the gravel.
Put the gravel on a shallow sloped area, 4:1 or less.
If you have dense cover near the bedding areas for the fry to hide in, that will add to the spawning success.
I didn't take any. I found some treated 2x6x10s in the cull pile at home depot. Cut 1 in half for the ends. Made a box with stainless steel screws. Stapled the fabric to it. I floated it out to around 6" of water, which should be 2.5' at pool and staked it so it wouldn't drift. Went to my local rock plant. Had them fill my bed up with a half ton of sand then a half ton of pea gravel on top of that. The pain was walking 5 gallon buckets through the mud to fill it. All in all, it wasn't a terrible experience. I hope these things make a difference. I'll have roughly $80 in each bed.