July Fly Fishing Report: San Juan River – Cold Water, Hot Action

Current Conditions – Flows & Water Temps

Right now, the river is flowing at 1050 CFS (that’s cubic feet per second, for the uninitiated). If it helps, one CFS is roughly the size of a basketball. So yeah… imagine 1050 basketballs rolling past you every second. You’re welcome for that visual. The flow will INCREASE to 1550 CFS July 31, dropping back to 1050 CFS on August 4th and back to 800 CFS on August 8th. This can be subject to change because this is New Mexico and you really never know.

Water temperature? Chilly and perfect. It’s coming out of the dam at 42°F, which means even in the heat of July and August, we’re fishing in cold, healthy water. No need to worry about fish stress—tailwaters like the San Juan are a summer fly fishing gem.

What’s Working – Fly Patterns & Techniques

🎣 Streamer Fishing

It’s been strong, especially for those willing to fish smaller streamers in the bait water. Fish are into it right now—get creative and cover water.

🪶 Dry Fly Fishing

Excellent in the evenings, especially on half-day floats. If you like watching fish rise, this is your window.

🪱 Nymphing

Well… nymphing is nymphing. It’s been consistent but moody:

• Mornings – Trashy bugs like mop flies, worms, leeches, red larvas.
• Afternoons – More technical, “buggier” fishing.
• Size matters – Dropping down to size 26 has been the key on pressured fish.
• Pro tip – High column rigs are the ticket. We’re seeing a lot of backs and tails—those fish are feeding in the upper third of the water column.

Where to Fish

• Quality Water: Fishing great. This stretch continues to deliver, even with summer pressure.
• Bait Water: Tougher unless you’re going small on streamers or fishing aggressively.

Final Thoughts – Don’t Sweat the Heat

A lot of anglers hesitate to book San Juan River Fly Fishing trips in July and August, but the truth is: tailwaters don’t care about summer heat. With cold water flowing all season long, the San Juan remains one of the best year-round trout fisheries in the country.

So whether you’re coming out this July, in August, or planning a trip for 2028 (or 2100) when our grandkids might be guiding—we’d love to have you on the boat.

See you on the water.
– James

📍 Book Your Trip:

Want to experience cold water, wild trout, and expert local guides? Book your San Juan River fly fishing trip with About Trout today.