There’s a small lake in southern Argentina that should sit high on the bucket list for anyone who’s ever fished for rainbow trout. It’s pretty much in the middle of nowhere, way out in an inhospitable desert only accessible by two-track roads. The closest point of civilization is Calafate, about six hours away. The waterbody’s official name is Lago Strobel, but anglers know it as Jurassic Lake for the reason you probably guessed: the rainbows there grow to prehistoric proportions.

However, the history of this fishery is nowhere near that old. Sometime in the mid 1990s, the owner of the surrounding lands sought to create a commercial trout rearing operation and planted the lake and some ponds with introduced steelhead from Argentina’s Santa Cruz River and rainbows from California’s McCloud. But without easy road access or launch sites, the trout farm idea wasn’t economically feasible. The landowner eventually abandoned the plan.

But no one told the trout. On a heavy diet of the lake’s prolific scud and nymph population, the fish quickly grew to gargantuan proportions—and reproduced vigorously in the adjacent Barrancoso River. As will happen in the fishing community, rumors spread. In 2006, two Argentine outfitters, Klaus Frimor and Christer Sjoberg, decided to see if the myth was true. It took them quite some time to actually find the lake, but when they did, they discovered trout averaging 10 pounds that would eat almost anything. El Dorado was found.

The fishery operated for years as a rugged tent camp—problematic in Patagonia’s notoriously violent winds. Luckily, outfitter Carlos Castanello purchased a long-term lease and built a cozy, modern fishing lodge a short walk from the mouth of the river. Just outside the dining room hangs a sign that reads: “Make Friends with the Wind.”

The lodge and its landscape–wild terrain for a trout pond.

While the conditions are regularly challenging, there really a bad time to visit Jurassic Lake Lodge. Their season runs from mid-September to May—the Southern Hemisphere’s spring to fall. I went for the first time in December and the second time in September of this year.

That three-month gap may not seem like much, but the fishing was a bit different. Our December trip, in Argentina’s spring, provided milder temperatures but the wind was intense. In September it was still pretty much winter and still very cold (we had snow flurries two mornings), but the wind was manageable. In December the spawning cycle was over and the trout were evenly disbursed along the lakeshore, around the mouth of the Barrancoso, and a ways upstream.

Where else do 30-inch rainbows like to eat big, bushy dry flies?

In September 2022, however, we arrived to find the rainbows in full spawning season. The river that had trout sprinkled throughout in December was now wall-to-wall fish. It looked like a sockeye run. Literally thousands of huge rainbows were fighting their way upstream to get to the spawning grounds. They were banging into each other, pushing through water so shallow that half their bodies were exposed. I saw several propel themselves over rocks, coming completely out of the water. This madhouse migration travelled up to a large pool they call "the Aquarium.” The rainbows use this pool to rest before moving farther upstream in a more relaxed manner. The river mouth and all the way up to the Aquarium was unfishable in September, but that really wasn’t a problem.

The lodge divides its fishing areas into three beats, with three anglers and one guide assigned to each. There is a rocky area known as the “Bay of Pigs,” there’s the river mouth, and then the Aquarium. From the Aquarium you can fish upstream into what becomes a small creek reminiscent of Montana, but full of 10-pound trout that readily hit dry flies. In September we literally had to move away from the mobs of spawning fish to avoid snagging them.

Tom Nygard working the “Bay of Pigs” on a windy day.

A normal day on Strobel begins around 8:30 a.m. after a hearty breakfast. We’d wader up and walk down to our assigned beats, fish till 1 p.m., then go back up for lunch. An hour later, we’d head back out to fish until dark. The wading is surprisingly easy: gravel bottoms where you rarely get in over your knees. That said, wind and waves are frequently factors along the lakeshore. It does die down sometimes in September though, and we experienced a few blessed days of dead calm. The fishing slowed down considerably when the wind disappeared, however, but would pick up to its usual frantic pace when the gusts returned. After much discussion at the lodge, we concluded that the wind probably stirs up the scuds and murks up the water—meaning the trout have more food available and may feel safer chasing it.

These are by no means skittish trout though. At times we would see 15-pound rainbows cruising so close to shore that we couldn’t even cast to them. The wind did make presentations challenging at times, so my rod of choice on the lake was a 10-foot Loop 8 weight. I felt the extra length helped keep the line out of the chop, but everyone else did fine with 9 footers. Several guys brought switch rods, but you never really had to cast very far, and I personally prefer fighting trout on the lightest rod possible. I used a 7 weight in the Aquarium and could have brought a 5 weight for dry fly fishing the river. Floating lines are all you really need, though I did try a sink tip on the lake. There’s a major drop-off a ways out, but the sinking line kept hanging up on it. Luckily, most of the fish seemed to sit above the ledge and along the shoreline, often in 2 or 3 feet of water.

Doubleheaders were common and kept the guides jumping.

One challenge a bored angler might pursue here is to find a fly these fish won’t hit. As usual, I brought some three pounds of flies but wound up using only three of them. On our first trip, my friend Rodger Glaspey brought some 2-inch mop flies that were magic. It was a relatively new pattern, sold in a 1-inch size that looked like a caddis nymph on steroids. The 2-inch version was hand tied and probably looked like some type of aquatic worm. Rodger ties this pattern with a mop chenille body, a contrasting fuzzy head, and a tungsten bead on a size 6 or 8 jig hook—which must be an important consideration. These fish often run more than 20 pounds and are incredibly strong, requiring heavy wire hooks to land. The Mega Mop, in a variety of colors, was the hot fly in December then again in September. Fished below a bobber, it gives a tantalizing action below the surface chop. At one point Rodger caught 10 fish on 10 casts, all over 10 pounds, all on the mop fly. He released more than 60 trout that day and 90% were on the Mop.

I swore by the elongated mop fly (the lodge sells them and calls it "the thing”) in December but didn’t use it that much in September. Anglers here will typically rotate flies until finding a hot pattern and stick to it. I tried an olive-green fuzzy streamer with a copper bead head that was dynamite. Orvis sells a small version of it with a hot pink head as a dragonfly nymph. The one I settled on was a bit bigger and fuzzier, but I wound up using it exclusively the last few days. A long 0X leader on a floating line gave it a perfect presentation, resulting in six monster rainbows past the 20-pound mark—Jurassic Lake’s holy grail. On my last day, I paid more attention to counting (Rodger’s incredible day was a challenge) and I released 65 rainbows up to 23 pounds. Fewer than six of them were under 8 pounds. And I quit two hours early.

The guys that fished dry flies did well with foam-bodied salmonfly imitations—though no such stoneflies exist here. Color didn’t seem to matter, but in the river the smaller sizes worked best. Using a big foam dry fly as an indicator with a scud or Prince Nymph dangling below was a killer rig. The only limitation is your imagination. After a few days we all had our own secret pattern. The fly collection at the lodge is excellent too and all their patterns work, but my advice is to bring every trout fly you own. They don’t weigh much, and you never really know which one will be your ticket to paradise.

Conservatively speaking, our group averaged more than 30 trophy rainbow trout every day, with 15 or more fish in the 20-pound-plus range. After the first day we stopped taking photos of anything under 15 pounds. We were literally fished out and exhausted by the time we had to return to Calafate and home. I’ve fished all over the world but have never experienced anything like Jurassic Lake—and probably never will.