Doubt it's a thermocline. Too early in the season, you would see more of an even/hard return line, and I believe something would show in the side imaging. You also have fish down there. It looks more like a sediment layer to me.
You have a couple of bait balls in mid-depths, baitfish on the surface, some feeding bass... So it could also be really spread-out baitfish.
2015 Skeeter FX 21
...and down goes PhotoBucket with the new Terms of Service... I predict they will be out of business or begging for forgiveness inside a month. 6/30/2017