It’s Minnesota
It's Minnesota

William O’Brien State Park

William O'Brien State Park is a Minnesota state park near Marine on St. Croix, covering 2,200 acres. Hours: Daily from 8 a.m. until 10 p.m. It offers camping or lodging. Entry needs a state park vehicle permit, $7 for a day, as the DNR fees page said on October 19, 2026.

Plan It In Three Lines

About The Park

The DNR describes it: A great "getaway" park only one hour from the Twin Cities, William O'Brien provides a beautiful setting for quality recreation along the banks of the St. Croix River. Hiking trails offer quiet exploration of the park's rolling, wooded hills. For anglers, the channels of the St. Croix have northerns, walleye, bass and trout.

Wildlife. Racoon, mink, beaver and woodchucks are prevalent. Upland meadows and woods provide a great environment for white-tail deer and fox. Birdwatchers frequently spot woodpeckers, bluebirds, orioles, herons, raptors and a variety of warblers.

History. The Dakota and Ojibwe Indians utilized the resources of the valley rich in fur-bearing animals, wild game and useful plants. In the 1600s, European trappers arrived to engage in the lucrative fur-trade industry.

Geology. Sandstone outcrops formed millions of years ago by inland seas are found along the St. Croix River. Glacial activity played a major role in developing the picturesque valley.

Visit Facts

Trails

SeasonTrail typeLengthNotes
SummerAccessible1.5 milesThe Riverside Trail is an accessible 1.5 mile loop that begins at the picnic grounds. It is self-guided with interpretive signs. There are places to stop and rest approximately every 900 feet, with benches at some of these areas.
SummerSelf-Guided—Riverside Trail loop, begins at picnic grounds.
SummerHiking—Trails range from easy to difficult, and pass through 12 miles of wooded areas, wetlands, and restored oak savanna areas.
SummerPaved Bike—The park has 1.5 miles of paved bike trails.
WinterGroomed Cross-Country Skiing Classic—Trails are groomed for both classic and skate skiing. The park's 12 miles of skiing trails range from easy to difficult. A Great Minnesota Ski Pass is required on groomed ski trails for skiers age 16 and up.
WinterGroomed Cross-Country Skiing Skate—Trails are groomed for both classic and skate skiing. The park's 12 miles of skiing trails range from easy to difficult. A Great Minnesota Ski Pass is required on groomed ski trails for skiers age 16 and up.
WinterSnowshoe—Snowshoers are allowed only on the 1.5-mile Riverside Trail. No snowshoeing is allowed west of the visitor center. Snowshoe rentals are available at the ranger station.

Camping And Lodging

TypeDetailNotes
Drive-in Sites—The park has 114 shaded and open drive-in sites.
Electric Sites—There are 71 electric sites across both campgrounds.
RV Length Limit—The maximum RV length is 60 feet. Length is measured from front of tow vehicle to rear of vehicle being towed.
Accessible SitesThree acessible campsitesThere are three ccessible drive-in sites with electric hookup, two in Savanna Campground, one in Riverway Campground.
Group Camp—The park has four rustic, tent-only group camp sites. Each site has running water and vault toilets. Sites 1, 2 and 3 accommodate up to 35 people. Riverside Camp accommodates up to 50 people.
Accessible Lodging—Vasa, Arcola and Marine Mills camper cabins are accessible.
Camper Cabins—The park has five camper cabins. No smoking, pets, or additional shelters are allowed at any of the camper cabins. Marine Mills, Arcola and Vasa camper cabins are accessible, available year-round, and accommodate five people. Otisville sleeps six and is available year-round. Copas accommodates five people and is not heated.

Reservations go through the DNR system; start from the park page.

On The Water

TypeDetailNotes
Fishing Pier—The accessible fishing pier on Lake Alice is closed due to the lake drawdown.
Swimming Beach—Located in the Walter F. Mondale Day Use Area, the swimming beach at Lake Alice is closed due to the lake drawdown.
Boat Access—Located in the Walter F. Mondale Day Use Area, the park's boat access is closed due to sediment buildup in the St. Croix creating unsafe conditions for launch.

Other Recreation

TypeDetailNotes
Picnic Area—The picnic shelter is in the Walter F. Mondale Day Use Area.
Picnic Shelter—The park has three open walled shelters. All shelters have electricity. There are two open shelters in the main picnic area; the larger one is accessible and has a fireplace. A third open shelter is located on Lake Alice, behind the beach area. Call the park to reserve.
Volleyball—There are two courts, one near the swimming beach, and one near the ball field. Borrow equipment from the ranger station.
Horseshoes—There are four horseshoe pits near the swimming beach and ball field. Borrow equipment from the ranger station.
Other—The park has a ball field with a backstop.
Warming House—The visitor center serves as a warming house in the winter.

Amenities

TypeDetailNotes
Ranger Station—Visit the ranger station for vehicle permits and park information.
Visitor Center—The visitor center has interpretive exhibits, drinking water, wood stove, and flush toilets.
Interpretive Exhibit—The visitor center features interpretive exhibits.
Naturalist Programs—Naturalist programs run year-round. View programs on the events calendar.
Gift Shop—The nature store is in the ranger station.
Rentals—Rent canoes, kayaks and paddleboards seasonally. Concessionaire shuttle service available seasonally, weekends only. Fishing kits (rod, reel, stocked tackle box), birding kits, sensory kits (headphones, fidget toys, calming toys), and GPS units are free to check out from the visitor center.
Firewood—Buy firewood at the ranger station or through Yodel. Gathering firewood can spread tree-killing insects and is against state park rules. Protect our trees – please burn only approved firewood!
Ice Sales—Ice sales are available seasonally.

Pets And Permits

Statewide, the DNR rules page says pets are welcome in state parks on a leash six feet or shorter, attended at all times; only service animals are allowed in buildings, lodging, tours and beach areas. A vehicle permit costs $7 a day or $35 a year (DNR fees page, read October 19, 2026). See the parks passport page for the full price list.

Park-specific: No smoking, pets, or additional shelters are allowed at any of the camper cabins.

Directions

The park is located 12 miles north of Stillwater. The park entrance is right on State Highway 95, 3 miles south of Highway 97 and 2 miles north of Marine on St. Croix. After turning onto the park road, the ranger station is immediately on your right. GPS coordinates: 45 13.521, -92 45.827 Using a GPS unit? Read this! If you are using a GPS unit, you must type in the following address to get to the park headquarters and main use area: 19074 St. Croix Trail North, Marine on St. Croix, MN 55047.

Map © OpenStreetMap contributors. Directions.

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Frequently Asked Questions

Where is William O'Brien State Park?

It is near Marine on St. Croix, Minnesota. The DNR address is 16821 O'Brien Trail North Marine on St. Croix, MN 55047.

How much does it cost to visit William O'Brien State Park?

A one-day vehicle permit is $7 and a year-round permit is $35 on the DNR fees page we read on October 19, 2026. Check the fees page before you go.

Are dogs allowed at William O'Brien State Park?

Pets are welcome on a leash six feet or shorter outside buildings, lodging, tours and beach areas, per the DNR rules page. This park’s page adds limits listed in Pets And Permits above.

Sources

  1. William O'Brien State Park (DNR Recreation Compass data) (read November 1, 2026).
  2. Minnesota state park fees (DNR) (read November 1, 2026).
  3. Minnesota state park rules (DNR) (read November 1, 2026).
  4. Minnesota State Parks Passport, all places, park fees and rules.
Cite this page: It’s Minnesota. “William O'Brien State Park.” itsminnesota.com/places/william-obrien/. Facts read from the sources above on November 1, 2026.