William O’Brien State Park
Where Prairie Meets the St. Croix — 1,520 Acres of River, Forest & Restored Savanna
William O’Brien State Park stretches across 1,520 acres along the bluffs and bottomlands of the St. Croix National Scenic Riverway — one of the original eight rivers protected under the 1968 National Wild and Scenic Rivers Act. Located just two miles north of Marine on St. Croix and about 45 minutes from the Twin Cities, the park offers a remarkable diversity of landscapes in a compact area: rolling glacial moraine, restored oak savanna, maple-basswood forest, wetlands, bogs, and direct river access.
Established in 1947 as the first state park in the Twin Cities metro area, William O’Brien traces its origins to lumber baron William O’Brien, whose daughter Alice donated the family estate lands to the state. Today, the park offers 124 campsites, 4 camper cabins, a spring-fed swimming lake, 12 miles of trails, and seasonal kayak/canoe rentals on the St. Croix. The Samuel H. Morgan Interpretive Center provides year-round educational programming, making this one of Minnesota’s most complete and accessible state park experiences.
Things to Do
Paddling the St. Croix
The park provides direct access to the St. Croix National Scenic Riverway:
- Rentals: Canoe, kayak, and paddleboard rentals available mid-May through mid-October
- River conditions: Generally calm in this stretch, suitable for beginners
- Important: Swimming in the river is not permitted due to strong currents
Swimming
Lake Alice, a 15-acre spring-fed lake within the park, features a sandy swimming beach and a fishing pier. The spring-fed water is clean and refreshing — a safe swimming alternative to the river.
Hiking & Nature
The park’s 12 miles of trails traverse remarkably diverse terrain:
- Restored oak savanna: Prairie grasses and wildflowers under scattered bur oaks
- Maple-basswood forest: Shaded canopy trails; spectacular fall color
- Wetlands and bogs: Boardwalk access to wetland ecosystems
- River bluffs: Overlooks of the St. Croix Valley
- A paved trail parallels Highway 95 for bicycling and wheelchair access
Wildlife & Birding
The diversity of habitats supports excellent wildlife viewing — white-tailed deer, beavers, foxes, and numerous bird species. The St. Croix River corridor is a productive bird migration route, particularly in spring and fall.
Trails
| Trail | Distance | Difficulty | Highlights |
|---|---|---|---|
| Savanna Trail | Varies | Easy–Moderate | Restored oak savanna; prairie wildflowers; open landscape |
| River Bluff Trail | Varies | Moderate | St. Croix Valley overlooks; forest canopy; seasonal wildflowers |
| Wetland Boardwalk | Short | Easy | Bog and wetland ecosystem; accessible; interpretive signage |
| Paved Bike Path | Multi-mile | Easy | Parallels Hwy 95; wheelchair accessible; connects to park entrance |
Camping
| Type | Sites | Amenities |
|---|---|---|
| Riverside Campground | Part of 124 total | Near St. Croix River; electric hookups available; showers |
| Blufftop Campground | Part of 124 total | Elevated sites; river valley views; electric hookups; showers |
| Camper Cabins | 4 | Heated; furnished; year-round availability |
| Group Camping | 4 areas | Large group sites; reservations required |
Best Time to Visit
| Season | Highlights | Considerations |
|---|---|---|
| Summer (Jun–Aug) | ⭐ Swimming at Lake Alice; paddling rentals; full camping; prairie wildflowers | Popular weekends; reserve early; mosquitoes near wetlands |
| Fall (Sep–Oct) | ⭐ Spectacular maple-basswood foliage; bird migration; cooler hiking | Paddle rentals ending; shorter days; campground closing |
| Spring (Apr–May) | Wildflower bloom; bird migration; river at high flow; savanna greening | Muddy trails; some facilities opening; variable weather |
| Winter (Dec–Mar) | Cross-country skiing; snowshoeing; camper cabin stays; winter wildlife | Cold Minnesota winters; some roads/facilities closed; dress warmly |
Visitor Tips
- Twin Cities escape: At just 45 minutes from Minneapolis/St. Paul, this is the closest full-featured state park for metro residents. Weekend campsite reservations fill early — book through the Minnesota DNR website.
- No river swimming: The St. Croix River has strong currents — swimming is not permitted. Use Lake Alice beach for swimming instead.
- Interpretive Center: The Samuel H. Morgan Interpretive Center offers year-round programs, interactive exhibits on local ecology, and is an excellent rainy-day option.
- Blufftop vs. Riverside: Choose your campground based on preference — riverside sites offer river access and sounds; blufftop sites offer elevation, views, and typically fewer mosquitoes.
- Historic Marine on St. Croix: The neighboring village of Marine on St. Croix is worth a visit — one of Minnesota’s oldest communities with a charming historic downtown.
Frequently Asked Questions
Can you swim at William O’Brien State Park?
Yes — swimming is available at Lake Alice, a 15-acre spring-fed lake within the park that features a sandy beach. Swimming in the St. Croix River is not permitted due to strong currents. Lake Alice also has a fishing pier for those who prefer angling.
Can you rent kayaks at William O’Brien State Park?
Yes — canoe, kayak, and paddleboard rentals are available at the park from mid-May through mid-October. The St. Croix River in this stretch is generally calm and suitable for beginners. Rentals provide direct access to the St. Croix National Scenic Riverway.
Last updated: April 2026
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