Big Spring Creek and Big Springs Trout Hatchery

Big Spring Creek starts at one of the largest artesian springs in the world, about 7 miles south-east of Lewistown in the foothills of the Big Snowy Mountains, and flows roughly 30 miles north-west through town to the Judith River. The spring pours out 50,000 to 64,000 gallons a minute of 52 °F water from the Madison Limestone, and the same water supplies Lewistown without needing treatment. Beside the spring is the Big Springs Trout Hatchery, the most practical place for a visitor to see it.

The hatchery was started in 1922 by the city of Lewistown and the local rod and gun club, and is now run by Montana Fish, Wildlife & Parks. In the 1930s Works Progress Administration crews added rock-walled ponds and stone bridges, and planted the willows around the spring; much of that work is still in place. Today it is the largest coldwater trout hatchery in Montana, producing more than 130,000 pounds of fish a year, including rainbow, brown and cutthroat trout. Visitors can walk past the raceways and, at a round display pool near the spring, buy a handful of food to feed the large trout. The adjoining city park has shaded picnic areas, shelters, restrooms and ball fields.

The creek itself is the other half of the visit. It has year-round trout fishing, and Lewistown is one of the few towns of its size where you can catch rainbow and brown trout inside city limits. FWP maintains six public fishing access sites along the creek, and a city trail system of more than 25 miles follows it through town. Downtown, the creek disappears for about three blocks: since 1922 it has run through a concrete conduit under the business district. In September 1877 Chief Joseph's band of Nez Perce camped along the creek during their flight from the army, and Métis families who settled where a freight trail crossed it in 1879–80 founded the settlement that became Lewistown.

The hatchery grounds are listed by Lewistown's tourism office as open every day from dawn to dusk and free, but some listings show weekday office hours only, so call 406-538-5588 before a weekend or winter visit. You need a Montana fishing licence to fish the creek.