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Trinity River Fishing Report | December 2025

Report by Matt Heron
Matt Heron of Matt Heron Fly Fishing is regional director for Cast Hope and reports for Catch America from Northern California rivers.
What is working right now

The Trinity River is one of California's best steelhead rivers, and Matt Heron fished it in low, clear, cold mid-December conditions for the Cast Hope tournament. Average adults run 21 to 28 inches, and Matt landed a 28.5 inch buck swinging flies with a two-handed spey rod. Indicator nymphing with a bobber and two flies is the most effective method. Winter fish are aggressive and moving.

How is steelhead fishing on the Trinity River right now?

Good, in low, clear, cold mid-December conditions. The Trinity is considered one of California's best steelhead rivers, usually a numbers game more than a size game. Average adults run 21 to 28 inches, with some fish over 30. Matt Heron landed a chrome 28.5 inch buck.

What is the most effective way to fish the Trinity River?

Indicator fishing. A bobber with a couple of nymphs below it is by far the most effective method, and most tournament teams used it. It fishes much like a typical trout nymphing trip and puts good numbers on the boat.

How do you swing flies for Trinity steelhead?

Cast down and across, mend, and swing on a tight line to the dangle, then pull off about three feet of line and repeat, stepping down the run. Start short so you do not line fish. Swinging targets aggressive fish that chase, so it catches fewer but delivers electric grabs.

What gear works for swinging Trinity steelhead?

A two-handed spey rod covers the wide, 70 to 80 foot river efficiently. Guide Brian Clemens set up sinking heads, from a pickpocket or Skagit with T8 up to T14, to dredge, plus lighter Scandi and mid-belly lines with fluorocarbon leaders for shallower transitional water.

What are half-pounders on the Trinity River?

Young steelhead of about 14 to 18 inches that have touched brackish but not full saltwater. They show a slightly black hue to their tails and backs, fight like steelhead, and can fill a slow day. Some 16 to 18 inch fish that never touched salt still look just like trout.

Watch the full report

From the report (Matt Heron): The average adult fish here is going to be somewhere from 21 to 28 inches. By far the most effective way to fish the Trinity River with a fly rod is with your typical indicator fishing bobber setup with a couple nymphs below it. I am swinging flies with a two-handed spey rod. That big buck I landed a little while ago was the highlight of the week for me.

Trinity River December 2025 FAQ

How big are Trinity River steelhead?

Average adults run 21 to 28 inches, with some fish over 30 inches caught each year.

What is the most effective Trinity River steelhead method?

Indicator nymphing with a bobber and a couple of flies below it.

What are the conditions on the Trinity River in December?

Low, clear, and cold, in between the fall and winter runs of fish.

What rod is used to swing flies on the Trinity?

A two-handed spey rod to cover the wide 70 to 80 foot river.

What are Trinity River half-pounders?

Young 14 to 18 inch steelhead that touched brackish water and show a slightly black hue.

How big was the steelhead Matt landed?

A chrome 28.5 inch buck, the highlight of the tournament for him.

What line setups dredge for winter steelhead?

Sinking heads like a pickpocket or Skagit with T8 up to T14 for deep, slow water.

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