William O'Brien State Park

This guide is for campers, cabin renters, paddlers and cross-country skiers. It covers the two campgrounds and cabins, trails, the current closures, costs and how to get there. Facts come from the Minnesota DNR park page, its live data feed and the 2026 DNR summer map unless noted; sources are at the end.

The park in brief

The DNR says lumber baron William O'Brien bought much of the land once owned by the lumber companies, and his daughter, Alice O'Brien, donated 180 acres for a state park in his memory. The DNR's two accounts give different years: the park page says 1947, the 2026 map says 1945. The park's size is also stated three ways: the DNR record lists 2,200 acres, the park page history says 1,653 acres, and the 2026 map says 1,880 acres.

The landscape mixes St. Croix floodplain, oak-hickory forest, white pine, marsh, oak savanna and upland prairie. For anglers, the DNR says the river's channels hold northerns, walleye, bass and trout.

Camping and cabins

The park has two drive-in campgrounds. The Savanna Campground is open year-round; the Riverway Campground is open mid-April through October.

The cabins, per the DNR lodging listing: Marine Mills, Arcola and Vasa are accessible, available year-round and sleep five; Otisville sleeps six and is year-round; Copas sleeps five, is not heated, and is open only April 1 through October 30. The DNR's sources do not fully agree: another note on the park page says the park has "three year-round camper cabins and two seasonal cabins" and that two year-round cabins and one seasonal cabin are accessible, and the 2026 map mentions "one of four camper cabins." ReserveMN shows what you can actually book.

Reservations: the park says all campsites are reservable and encourages booking ahead; it also says "any site not reserved is available for drop-in camping for one night only," using self-registration if staff are away. The statewide DNR reservation FAQ says all state park campsites require a reservation, allows booking up to 120 days ahead, opens new dates at 8 a.m. Central, and charges no reservation fee for same-day bookings. The state park reservations guide explains how ReserveMN works.

Season facilities: showers and modern restrooms run from late April through mid-October, and the dump station (campers only) runs the same months.

Trails and things to do

The park also has two all-terrain track chairs that can be reserved for designated trails, three open picnic shelters with electricity, two volleyball courts, horseshoe pits and a ball field.

Rentals and loans: canoe, kayak and paddleboard rentals run seasonally, with a weekend-only concession shuttle in season, per the DNR. The visitor center lends fishing kits, birding kits and GPS units for free.

For more St. Croix Valley parks, see the Afton State Park guide and the Interstate State Park guide.

Closures and alerts as of November 2026

From the DNR alert (updated November 11, 2026):

• Deer hunt: the entire park is closed to the public November 14 to 15, 2026, for a special hunt; only drawn hunters with a valid permit may enter. Normal camping and day use resume November 16. The DNR suggests Interstate, Wild River, Fort Snelling and Afton as alternatives that weekend.
• Lake Alice: in early August 2025 a mechanical failure of the lake's water control structure drew the lake down. The DNR plans to replace the structure and dredge the public water access. The Lake Alice beach, fishing pier and accessible canoe and kayak launch are closed until construction is complete, estimated fall 2027.
• St. Croix water access: closed "due to low water levels and high sediment." The alert says small, non-motorized boats can still launch, and motorized boats should use alternate launches such as Osceola or Somerset landing.
• Season close (since October 19): the dump station, campground showers and restrooms, jug fillers, Day Use Area flush toilets, the Riverway Campground, the Wedge Hill and Riverside group camps, the walk-in sites and some Savanna loops are closed. Vault toilets stay open in the Day Use Area and Savanna Campground, flush toilets are at the visitor center during park hours, and RV tanks can be filled with drinking water behind the ranger station.
• Rentals: canoe and kayak rentals are closed for the season.

Winter at William O'Brien

• Camping: Savanna Campground stays open year-round.
• Skiing: 12 miles of trail groomed for classic and skate skiing, easy to difficult. A Great Minnesota Ski Pass is required for skiers 16 and older.
• Snowshoeing: only on the 1.5-mile Riverside Trail, and none west of the visitor center. Snowshoes can be rented at the ranger station.
• Warming house: the visitor center, which has a wood stove, drinking water and flush toilets.

Fees and permits

From the DNR vehicle permit page and fee schedule, before tax:

Example (derived from the ranges above): two nights in a camper cabin is 2 × $80 + $8 = $168 at the low end, or 2 × $90 + $8 = $188 at the high end, before tax, plus a vehicle permit ($7 overnight or $35 year-round). For multi-night stays, ask the park which permit covers your whole stay; the year-round permit covers every visit for a year.

Getting there

The entrance is on Highway 95, 3 miles south of Highway 97 and 2 miles north of Marine on St. Croix. The ranger station is immediately on the right after you turn onto the park road. The DNR says GPS users "must type in" 19074 St. Croix Trail North, Marine on St. Croix, MN 55047 to reach the headquarters and main use area; the park's coordinates are 45 13.521, -92 45.827. The nearest town is Marine on St. Croix.

Find more Twin Cities and St. Croix Valley guides or use the park finder.

Before you go

1. Avoid November 14 to 15, 2026, when the park is closed for the hunt.
2. Do not plan on Lake Alice swimming or pier fishing until the reconstruction ends.
3. Use the GPS address, not the mailing address.
4. In winter, book a Savanna Campground site or a year-round cabin; Riverway and Copas are seasonal.
5. Motorized boaters: check the St. Croix access status and the Osceola or Somerset alternatives.
6. Buy firewood at the ranger station or through Yodel; gathering wood is against park rules.

Related guides: Afton State Park · Wild River State Park · Interstate State Park · Minnesota state park reservations explained

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Sources

• Minnesota DNR, William O'Brien State Park (camping, lodging, trails, alerts, directions): https://www.dnr.state.mn.us/state-parks/park.html?id=spk00283
• Minnesota DNR, William O'Brien State Park summer map and guide (PDF, 2026): https://files.dnr.state.mn.us/maps/state_parks/spk00283_summer.pdf
• Minnesota DNR, State park fees: https://www.dnr.state.mn.us/state_parks/fees.html
• Minnesota DNR, Vehicle permits: https://www.dnr.state.mn.us/state-parks/permit.html
• Minnesota DNR, Reservation FAQ: https://www.dnr.state.mn.us/reserve-faq/index.html