Brush Lake State Park, Montana

Brush Lake State Park is a public area located in the corner region of north-eastern Montana. It is about four miles east of the small unincorporated Montana community of Dagmar, near Plentywood, close to the Canadian border.

This state park is a natural wonder that serves as a hub of recreational activity within the area and is based around the glacially formed lake.

The park is known locally as a haven of peaceful quiet, especially when the open night skies come into play. In fact, Brush Lake State Park’s remoteness and northern latitude make it a popular destination for stargazing among some locals.

The lake itself, which is surrounded by grass fields, has a distinctive aquamarine blue color, similar to many of the lakes on the Northern Great Plains. The body of water is unique in some ways in terms of its depth, biology, and hydrology.

When the glaciers were playing their part in forming the Montana landscape as it stands today, the lake was formed as a forest grew over a buried, slowly melting ice block, which eventually left the depression that is today the 65-feet deep Brush Lake.

The minerals in the lake come from the glacial deposits which dissolve and accumulate, and they are responsible for the lake’s distinct color. This mineral-rich water is ideal for particular types of algae and bacteria to thrive in, and they cause limestone to form on the lake bottom. The result is year-round fresh, clean water, and Brush Lake is one of the few lakes in the world where this process occurs.

Another unique aspect of the lake is that it cannot contain fish. Various attempts have been made to stock it with fish over the years but to no avail. The biological theory is that all the oxygen in the groundwater is so involved in the dissolution of the calcium-rich gravels in the lake, that the water is under-oxygenated in terms of supporting the fish.

Brush Lake’s water is also considered to be closer to seawater than freshwater, which is hardly a breeding ground for sport fish. Brush Lake is still a water recreation area though, and it is to the delight of many boaters and swimmers that there are no fishermen.

Brush Lake began to attract visitors in the first decade of the twentieth century when more and more local residents became drawn to the clear and clean, deep, spring-fed waters of the lake and its surrounding greenery.

Apparently, Hans Christian Hansen built a summer resort on the lake after having homesteading papers accepted in 1914, and by 1920 the grounds had a bar and cafe, with an additional dance hall coming in the 1940s.

The state purchased 450 acres surrounding the northern half of the lake in 2004, and the state park status soon followed, although the southern portion of the lake retained its private ownership.

Public access is thus restricted to the northern portion of the large lake, where there is a day-use area including a campground. The Brush Lake State Park is managed by the Montana Department of Fish, Wildlife, and Parks, and there is a day-use entrance fee of $8 with a vehicle or $4 on foot or bicycle for non-residents.

Brush Lake State Park Stats

  • 280-acre lake
  • Accessible between May and November
  • Open 7am-10pm
  • Over 12 camping sites

Main Attractions

The Lake

This clean and clear, mile-long lake is ideal for swimming, wildlife viewing, motor-boating and water skiing. You can find sandy beaches along the way here, but sadly there is no fishing at all to be found due to the mineral make-up of Brush Lake.

The North/Northeast section of the lake is where to find the day-use area where there is also a boat ramp & dock if you bring a boat, and this is the vicinity of both the picnic area and the 12 site campground.

Recreation Activities

So aside from bird watching, boating and canoeing, swimming, hiking, motor-boating, and picnicking, the camping aspect is another one of the park’s main draws. RVs and tents are part of the setup, and the camping is in close proximity to the lake.


This is a 12-site campground which is open between May and November, and consists of 10 campsites with electricity and 2 double campsites without. The sites are right next to the lake but camping is only allowed in designated areas. The campground region around the lake has vault toilets, picnic tables, fire rings, and a designated swimming area.

There is a maximum capacity limit of eight people at each individually signed or numbered campsite, which features a single camping unit including either a tent, a motor home, a camping bus, or some other device used for sleeping.

The sites designated as double sites have a doubled capacity which permits sixteen people and two camping units. Pets are allowed but must be kept leashed, and campfires are allowed in designated areas only.

Services and Amenities in the campgrounds include ADA access, a boat launch, a dock, electricity, established fire pits, parking, trash removal, and water.

The campgrounds have a few other rules like the enforcement of quiet hours between 10:00 pm and 7:00 am, and check-in and check-out times are 2-3 pm and 12-1 pm respectively.

Campsite fees range from $4-$34 per night, depending on the season and available amenities. The site is 30 miles to the east of Plentywood, and you can get there from Highway 16 going in an eastern direction towards Highway 258.

After about 16 miles, you turn south on Brush Lake county road which brings you to the site after a mile and has directions and signs.


Trail Routes

Brush Lake Walk

This is a fairly remote region with little by way of mountainous terrain or long hiking trails. Brush Lake Walk is the main trail route close to the lake and is just over a mile in length.

This is a rather lightly trafficked out and back trail that stretches along a section of Brush Lake. It is not challenging and hence suitable for all skill levels, with elevations of not more than 50 feet.

The trail is used primarily for walking, but you may encounter a few bird watchers along the way too. Dogs are allowed under the condition that they are kept on a leash.

Spring Lake Loop

Around half an hour away from Brush Lake, near Williston in the region of North Dakota, you can find the Spring Lake Loop. This is an easy loop trail of almost 1.5 miles in the vicinity of another small lake and a park area.

The route is a small trail that won’t prove too challenging for anyone. It is used mainly for walking, running, and road biking, and again there will be a few bird-watchers around as the area is rich in waterfowl and other migrating birds. Dogs on a leash are also allowed on this trail and you could even do a spot of fishing in the lake here if you really need to cast a line or two.

Ice Cave Loop

If you really feel the need to hike somewhere with slightly more variation in the terrain and you don’t mind going out from the region of the state park further still – in around an hour-and-a-half you could skip over to Arnegard in North Dakota, where there are a number of decent and more diverse trails.

Sperati Point via Achenbach Trail is a moderate out and back trail of just under 2.5 miles in length. It is near Arnegard and the route includes plenty of picturesque wildflowers and various opportunities for a number of other activities.

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