Fishing Report: Blue River - Dillon Dam 10.21.24

Flowing out of Dillon Reservoir, the Blue River is a well-known tailwater fishery prized for its cold, clear waters and large, wary trout. Below the dam, you'll find trophy-sized rainbow and brown trout, with the best fishing happening in the afternoons as the water warms slightly. Mysis Shrimp and midges are staple food sources, and precise presentations with light tippets are critical. The river has excellent access points near Silverthorne and Green Mountain Reservoir, with challenging yet rewarding fishing for those willing to put in the effort. Nymphing and small midge patterns are most effective, with occasional streamer action in deeper pools. The Blue River operates under Gold Medal regulations, requiring catch-and-release for certain stretches.

September Fishing Report: Blue River

Current River Conditions

The Blue River is currently flowing at 108 CFS below Dillon Reservoir, with water temperatures ranging between 39°F and 45°F. This consistent cold flow from the reservoir makes the river a prime spot for afternoon fishing, as trout feeding improves with the slight rise in temperature later in the day. The water is crystal clear, so anglers need to focus on stealth and perfect presentations with light tippets to target the cautious trout in these conditions.

The Blue River features strong hatches of midges, Tricos, and Blue Wing Olives (BWOs), making small nymph patterns like Zebra Midges (#20-24) and dry flies such as Parachute Adams (#18-22) effective choices. Streamer fishing can also produce results, especially in deeper pools near Green Mountain Reservoir

Flow Rate: Currently around 108 CFS below the Dillon Reservoir, which is typical for this time of year.

Water Temperature: Ranges from 39-45°F, keeping the trout feeding window tight, especially during the afternoon.

Clarity: The water is crystal clear, demanding stealthy presentations and light tippets.

Best Times to Fish: Midday to late afternoon, as the water warms up slightly. Expect strong hatches of midges, Tricos, and Blue Wing Olives.

For real-time data on river conditions, visit the Colorado Division of Water Resources.

Hatches & Recommended Flies

Nymphs

• Zebra Midge (#20-24) – Effective throughout October as midges remain one of the most consistent food sources. Fish them deep in runs and pools, especially in the mornings when trout are feeding subsurface.
• RS2 (#20-22) – Perfect for afternoons when Blue Wing Olives (BWO) are hatching. Use this nymph in deeper runs and riffles where trout are actively feeding.
• Mysis Shrimp (#16-20) – Best used below Dillon Reservoir year-round, especially in October when other food sources are limited. Trout feed heavily on these shrimp, so nymphing with them in the tailwater section is highly productive.
• Black Beauty (#20-24) – Great for targeting trout feeding on midge larvae during mid-morning to early afternoon. Best used in slower runs and pools.
  

   

Dry Flies

•  Blue Wing Olive (BWO) (#18-22) – Effective on overcast days in October, as BWOs are prevalent. Use these during late morning to afternoon when the hatch peaks, and target rising trout in seams and eddies.

• Parachute Adams (#18-22) – A versatile dry fly, ideal for afternoon fishing when trout are actively feeding on mayflies. Cast in riffles and slower-moving sections.

• Griffith's Gnat (#20-24) – Best used during midge hatches in calm, clear water. Fish this fly in slower pools during the afternoon to target rising trout.

Streamers

•  Pat’s Rubber Legs (#8-10) – Fish these streamers early in the morning or late in the afternoon in deeper pools and near structure like undercut banks. Ideal for targeting larger, aggressive trout.

• Sculpzilla (#6-10) – A solid choice for deeper waters and targeting larger trout. Strip or swing through pools during low-light conditions for the best results.

Fishing Tactics

Nymphing Techniques for the Blue River

The Blue River is no place for a lazy cast; nymphing here is your bread and butter. With its crystal-clear water, every presentation must be precise and stealthy. Set up with a small indicator, and be prepared to adjust based on depth. When the trout aren't showing interest on the surface, it's time to rely on your nymphing skills.

High-Sticking Nymphing: This is a killer technique for the Blue’s deeper runs and riffles. Keep a tight line with minimal slack to feel those subtle strikes. High-sticking is especially effective in the upper sections below Dillon Dam, where trout are holding in fast water.

Two-Fly Nymph Rig: Want to cover multiple depths? Start with a heavier attractor pattern like a Mysis Shrimp or Pat’s Rubber Legs as your point fly. Follow it up with a smaller, more imitative pattern like a Zebra Midge or RS2 as a dropper. This setup will target bottom-feeding trout and those cruising higher in the water column.

Adjust Depth and Weight: You’ll need to fine-tune your rig based on flow and water depth. Add enough split shot to get your flies down quickly into the strike zone, especially in the Blue’s deeper pockets. Use a drag-free drift to avoid spooking fish and use strike indicators to help detect subtle takes.

Dry Fly and Dry-Dropper Fishing

While the Blue is often dominated by nymphing, don’t neglect the potential for dry flies. When the hatches are on, trout will rise, and that's your opportunity. Blue Wing Olive (BWO) hatches in the fall offer prime dry fly opportunities. Pair a Parachute Adams or Griffith’s Gnat as your indicator fly with a small nymph like an RS2 hanging below for a versatile dry-dropper rig. Target seams and soft pockets where fish are likely to rise.

Streamer Fishing

Streamer fishing on the Blue River can be incredibly effective for landing larger trout. Cast streamers like Pat’s Rubber Legs or Sculpzilla into deeper pools or along undercut banks. Swing or strip them through the slower-moving sections to entice aggressive strikes. Early morning or late evening is prime time for streamers, especially when the water is clear, and trout are more likely to chase larger prey.

Sight Fishing and Stealth Tactics

The Blue River’s transparency demands a stealthy approach. Polarized sunglasses will help reduce glare, allowing you to spot trout in deeper pools or runs. Keep a low profile and use long leaders (9-12 feet) with light tippet (5x-6x) to reduce visibility. Approach the water with caution, and focus on subtle signs of fish activity like surface disturbances or bubbles.

Access Points:

Silverthorne Outlet Section (Below Dillon Reservoir):

• Description: Easily accessible right in the heart of Silverthorne, near the outlet stores. This section below the Dillon Reservoir is known for its large, finicky trout that feed on Mysis Shrimp. It offers consistent water conditions, but can be crowded due to its popularity.

• Why Fish Here: Excellent year-round access to trophy-sized trout. Nymphing is highly effective here with Mysis Shrimp and small midges.

Blue River Campground:

• Description: Located near Green Mountain Reservoir, this area provides access to a quieter stretch of the river. The campground also offers overnight accommodations for anglers looking to fish multiple days.

• Why Fish Here: Less crowded, with good access to deeper pools where larger trout often hold. Streamer fishing can be productive here, especially early in the morning.

Green Mountain Reservoir Tailwater:

• Description: A more remote but rewarding access point, located below Green Mountain Dam. It involves a bit of a hike, but the fishing here is worth the effort. The water flow is regulated, offering more predictable conditions.

• Why Fish Here: Excellent for those looking for solitude and a shot at big trout in deeper water. Nymphing and streamer fishing are ideal in this section.

Blue River Below Silverthorne:

• Description: As you head downstream from Silverthorne, there are multiple access points along the river that provide great fishing opportunities with less crowding. The water picks up volume from tributaries, making it an ideal spot for targeting large trout.

• Why Fish Here: A great area for anglers looking to avoid the crowds at the outlet section, with good opportunities for both nymphing and dry fly fishing.

Columbine Landing:

• • Description: This is a quieter section of the Blue River, located further downstream. Known for big brown trout, it's a great spot to escape the crowds and focus on streamer fishing.

  • Why Fish Here: Ideal for fishing in relative solitude, with chances to land larger fish using streamers in deeper runs.