Matching the Line to the Mission: A Guide’s Take on Streamer Setups

Most anglers obsess over flies. We debate shades of olive, count rubber legs, and argue about whether the head of a Rusty Trombone should be gold or copper. But the truth is, the most important piece of your streamer setup isn’t dangling off the end of your tippet — it’s the fly line.

When you’re throwing streamers, the line is the system. It determines how deep you fish, how your fly swims, and how much contact you have from rod tip to hook point. Pick the wrong line and even the prettiest streamer in your box just drags through dead water. Pick the right one, and everything suddenly clicks.

Here on the San Juan, we’ve spent more time than we’d like to admit field-testing lines, rods, and rigs from the boat and on foot. We’ve spent hundreds of hours streamer fishing the San Juan — from low, clear fall water to high, green spring pushes — we keep coming back to three Cortland lines that flat-out work.

The All-Around Workhorse: Cortland Sink 10

If we had to fish one streamer line for the rest of the season, it’d be the Cortland Sink 10.
It’s the do-everything line that lives on most of our seven-weights (the Echo Streamer X being a favorite).

With a 28-foot head and a perfectly balanced sink rate, the Sink 10 is the line we trust when we’re wading. It lets you stay tight to your flies without feeling like you’re fighting your own line. Whether you’re working a shallow shelf or picking apart mid-depth structure, it keeps the fly in play — not buried in the mud or skating out of the zone.

It also handles the kind of rigs we actually fish out here: double-streamer rigs, articulated meat, or some new creation fresh off the vise . It carries the weight without blowing up the cast or overloading the rod. Simple, predictable, effective — everything a streamer line should be.

For Getting Deep: Cortland Rock Bottom

Then there are those days when you need to put the fly in the basement.
Heavy current, deep buckets, or that big brown sulking on the bottom of “Death Row.” That’s when the Cortland Rock Bottom earns its keep.

We throw the 300-grain version most often. It shares DNA with the old Airflo Streamer Max Long, but Cortland made it smoother and more boat-friendly. The thicker running line doesn’t tangle when you’re standing in the rower’s footwell, and it shoots clean. It’s a specialty tool — not an everyday line — but when you need to cut through chop and hold a fly in the zone, there’s nothing better.

The Boat Angler’s Choice: Cortland Sink 15

If your streamer fishing mostly happens from a drift boat — not the bank — the Cortland Sink 15 splits the difference beautifully.
It gets down fast enough for typical float sections but still lets you control the swing and retrieve without dragging bottom. We think of it as the perfect “set it and forget it” boat line — one that covers 80% of the conditions you’ll face without constantly swapping spools.

Final Thoughts

Streamer fishing isn’t about luck, it’s about getting your fly in front of a fish that’s ready to eat.
The right line makes that happen.

• Wade anglers: Start with the Sink 10 — it’s your bread and butter.
• Heavy water or deep slots: Rig a Rock Bottom.
• Dedicated boat anglers: The Sink 15 keeps you fishing efficiently all day.

The fly might get the credit, but it’s the line that does the heavy lifting.
Dial that in, and everything else — the cast, the retrieve, the eat — starts to feel easy.

(This fish ate a large fly fished on a Cortland Sink 10 on New Mexico’s San Juan River)