Fly Fishing Stream Conditions Report: Blue River - Below Dillon Reservoir Silverthorne

This year: The Blue River below Dillon Reservoir is settled into its technical fall season, presenting low, clear tailwater conditions with flows steady at 54 CFS. Water temperatures are averaging 40 to 44 degrees. As the river runs clear, successful angling requires a transition to delicate tailwater strategies, prioritizing sight fishing and careful approaches over constant fly changes. Target your efforts deliberately around deeper slots, boulder pockets, and subtle current seams. Using light 5x tippets and tiny flies in the 22 to 24 size range is critical. Microscopic depth adjustments will make a significant difference in these low flows. With cold-water midges and small Baetis active, leading with a Mayer's Mysis Shrimp or a Tim's Mysis is highly effective. Follow up with tiny nymphs such as a Zebra Midge, WD40, or a Pheasant Tail Nymph to match the drift. Be aware that brown trout are entering their spawning season; please watch your step to avoid active redds and spawning fish.

Best time of day: Afternoon

Prior years: The Blue River is running low and incredibly clear, making the resident trout highly observant. To find success in these conditions, take a stealthy approach. Keeping a low profile and kneeling to sight fish will help you spot more fish while spooking fewer of them. Late morning through early afternoon offers the best fishing window, particularly when the light flattens. A midday clarity window provides great opportunities for technical angling. During this time, look for fish rising to steady midges. Light nymph rigs and small dry flies are the ticket, with micro leeches also producing near the dam on cloudy days. Anglers can expect to see big rainbow trout actively shadowing spawning brown trout. When rigging up, stick to ultra-fine presentations. Small patterns like RS2s, Black Beauties, and orange scuds are key to fooling these smart tailwater fish.