http://www.diamondlake.net/1005/Page.aspx
From ODFW:
Head out to Diamond Lake for some of the state’s best trout fishing. Big fish, big lake, big views – Diamond Lake has it all! Spend a day at Oregon’s Gem of the Cascades or stay a while at the Diamond Lake Resort or Forest Service Campgrounds.
Diamond Lake is stocked with rainbow trout that grow fat on summertime bug hatches. The lake is open year-round, including ice fishing. Some of the best fishing is after ice-off in April, May and early June. Fall fishing is also fabulous – and peaceful – when tourist season slows and water temperatures begin to cool.
Bank anglers can fish near the resort, near Lake Creek and throughout Forest Service Campgrounds. The best boat fishing is on the south end of the lake near Silent Creek and on the north end in deep waters. Trolling with a variety of spinners and lures is effective. When anchored near Silent Creek or Lake Creek, try flies or PowerBait.
2015 Fishing Season Highlights
Season open - minimum length with one over 20 inches and 2 daily limits in possession.
Fish stocking: 300,000 fingerlings.
NO LIVE FISH USED FOR BAIT! Report anyone using live fish for bait to Oregon State Police at 541-440-3334 or the TIP line, 1-800-452-7888.