Jumbo rainbow trout, averaging 4–6 pounds, planted through the cooperative WDFW / Lower Chehalis Basin project, change the lake in May. They do not change the rules.
Big fish still want the right depth, the right presentation, and the week right after a plant — which is a different fishery from the week after that.
The guide's trout playbook page carries the stocking table and the May card, so you can fish the plant instead of fishing a rumor.