Pathfinder Reservoir is a vast, remote reservoir at the confluence of the North Platte and Sweetwater rivers in central Wyoming – a trophy-trout and walleye lake set in stark red-rock and sagebrush country, held behind a historic stone dam that’s a National Historic Landmark. Wild, windy and rarely crowded, it rewards anglers and boaters willing to venture into Wyoming’s wide-open spaces.
This guide covers Pathfinder Reservoir: the historic dam, the fishing, the wildlife refuge, and access. It’s part of our growing Wyoming Lakes Database.
Pathfinder Reservoir at a glance
- Surface area: ~22,000 acres at the North Platte-Sweetwater confluence
- Location: Natrona County, central Wyoming (southwest of Casper, near Alcova)
- Built: Pathfinder Dam, completed 1909 – a National Historic Landmark stone-masonry dam
- Top fish: rainbow, brown & cutthroat trout, walleye
The historic Pathfinder Dam
Pathfinder Dam is one of the oldest large dams in the West – a graceful stone-masonry arch completed in 1909, hand-built from local granite in a narrow canyon below the river confluence. Now a National Historic Landmark, it has a small interpretive center and an unforgettable setting. The reservoir it created was named for explorer John C. Frémont, “the Pathfinder,” whose ill-fated 1842 boat trip foundered nearby on the Sweetwater.
Fishing Pathfinder Reservoir
The big, deep, cold reservoir is a strong fishery for rainbow, brown and cutthroat trout, along with walleye. A Wyoming fishing license is required. The size and remoteness mean you can find quiet water, but they also demand self-reliance – and the lake is notoriously windy, building big waves fast, so watch the forecast and respect the conditions.
The refuge and recreation
The Pathfinder National Wildlife Refuge surrounds parts of the reservoir, protecting habitat for pelicans, waterfowl, pronghorn and sage grouse in the high desert. Boat ramps and primitive campgrounds serve anglers and boaters, but there’s little development – this is a fishing-and-solitude lake. Neighboring Alcova Reservoir is just downstream, making a natural pair.
Getting there and what’s nearby
Pathfinder Reservoir is southwest of Casper near Alcova, off WY-220 and county roads, about 45 minutes from the city. The Oregon Trail landmarks of Independence Rock and Devil’s Gate, and Fremont Canyon, are all nearby.
Know before you go
- Fishing license: a Wyoming license is required.
- Remote & windy: big, exposed water with few services – come prepared and watch the wind.
- History on site: the 1909 Pathfinder Dam and its interpretive center are worth a stop.
Frequently asked questions
What fish are in Pathfinder Reservoir?
Rainbow, brown and cutthroat trout, plus walleye, in big, deep, cold water.
Why is Pathfinder Dam historic?
Completed in 1909, it’s a hand-built stone-masonry arch dam and a National Historic Landmark – one of the oldest large dams in the West.
Where is Pathfinder Reservoir?
In Natrona County, central Wyoming, southwest of Casper near Alcova, off WY-220.
Related: explore more of the largest lakes in Wyoming, or head back to the Wyoming Lakes Database.
