Thompson Chain of Lakes, Montana, USA

Lake Locations:

USA - West - Montana - Glacier Country -

Also known as:  Loon Lake ,Horseshoe Lake, Chrystal Lake, Upper Thompson Lake, Middle Thompson Lake, Lower Thompson Lake, McGregor Lake, Lavon Lake, Little Loon Lake, Banana Lake, Bootjack Lake, Cad Lake, Cibid Lake, Lilly Pad Lake, Myron Lake, Rainbow Lake,Topless Lake

Most visitors driving along US 2 in Montana’s Glacier Country region have likely admired the Thompson Chain of Lakes as they passed. Located about 45 miles south of Libby, the group of glacial kettle lakes along the highway present a lovely view of one of Montana’s more remote vacation destinations. Although called a ‘chain’, most of the lakes are not connected. The group is considered the headwaters of the Fisher River and is much loved as a relaxation and recreation site.

Stretching 20 miles along the highway, the Thompson Chain is dominated by several large lakes surrounded by many smaller ones. The Pleasant Valley River flows into westernmost Loon Lake before the chain continues eastward with Horseshoe Lake, Crystal Lake, Upper Thompson Lake, Middle Thompson Lake, Lower Thompson Lake and McGregor Lake. The outflow is the Fisher River, a tributary of the Kootenai River system. Streams between the lakes are mostly intermittent and not navigable by boat. The area between the lakes is partly wetland, with much of the water coming from springs and ground seepage. Nearly all of the Thompson Chain of Lakes are clustered together, with Lavon Lake, Little Loon Lake, Banana Lake, Bootjack Lake, Cad Lake, Cibid Lake, Lilly Pad Lake, Myron Lake, Rainbow Lake and Topless Lake arrayed around the larger lakes. Several of the named lakes are under 20 acres and often quite shallow. Five miles to the east, large McGregor Lake and its satellite, Little McGregor Lake lie along Hwy 2. Most accounts claim 19 lakes within the chain, but others proclaim the actual number is higher as several unnamed ponds dot the landscape. A few of the lakes are private and inaccessible.

Thompson Chain of Lakes is named after David Thompson, a land surveyor who first described the lakes in his 1811 journal. The lake quickly became a spot for the long-dreamed-of remote cabin or fishing trip. Although much shoreline is private property, a forestry company owns a large acreage and provides access to the public. Logan State Park, operated by Montana Fish, Wildlife & Parks, holds a 17-acre section of the north shore of Middle Thompson Lake. The state park, set amid Douglas fir, ponderosa pine and larch, has space for a total of 83 campsites, picnic tables, fire ring, vault toilets, drinking water, a swimming area and boat launch ramp. A day-use area offers picnic tables and fire grates near the beach. Group camping is available to large groups. Ice and firewood can be purchased on-site. The McGregor Lake Campground has 27 campsites that are operated by the US Forest Service. A number of primitive campsites are scattered along Lower, Middle, Upper Thompson Lakes, Horseshoe Lake, Loon Lake and some of the smaller lakes.

Middle Thompson and Upper Thompson Lakes are no-wake lakes, as are Loon Lake and many of the smaller lakes. McGregor Lake is open for such sports as water skiing and has a larger launch area. The entire lake system has nine state ‘fishing access’ boat launch sites, with a small launch fee charged. Wildlife is plentiful with nesting loons regularly seen in some areas. These nesting areas are marked by buoys and are off-limits to boaters so the loons are not disturbed. Whitetail deer, mule deer, elk and other native mammals are often seen, along with a multitude of songbirds. The only designated hiking trail is located at McGregor Lake, a 2.9-mile trail along the shoreline. Locals say the huckleberry picking here is great. Roads in the area are rough and not suitable for motor homes or low-clearance vehicles, but walking or bicycling the gravel roads will lead to most of the lakes.

The Thompson Chain of Lakes is excellent for fishing. They hold cutthroat trout, brown trout, rainbow trout, brook trout, yellow perch, kokane, largemouth bass, smallmouth bass, northern pike, mountain whitefish and pumpkinseed. The trout are stocked annually. An ice fishing tournament is held each winter on Lower Thompson Lake. McGregor Lake holds some very large mackinaw trout. More about McGregor Lake can be found on the McGregor Lake page. Some lakes have special fishing regulations, so a current copy of the fishing regulations should be obtained when buying a fishing license.

In lieu of camping, those looking for a more substantial type of lodging needn’t drive clear to Libby or Kalispell. Several resorts exist on Crystal Lake, McGregor Lake and some of the other lakes. Often, these guest lodgings are geared to fishing, with guides and supplies available. Crystal Lake in particular has private cottages, but sections of Upper Thompson and Middle Thompson Lakes also have some development. Check the Crystal Lake page for more information. McGregor Lake has resorts and private lodgings. The forestry concern that owns much of the private land near the lakeshore has recently been expressing interest in selling some of the property. Local officials are working with them to develop a land-use and development plan, as everyone concerned wants to keep the wilderness flavor of the lakes as much as possible.

The Cabinet Mountains enclose the south side of the Pleasant Valley, and the Salish Mountains rim the north. Nearby are large tracts of the Kootenai National Forest, offering rugged hiking trails, remote lookout towers and a number of peaks over 6000 feet. Because Thompson Chain of Lakes area is some distance from large cities, those who come here from places like Missoula intend to spend a few days or a week. Often those who have driven US 2 from Glacier National Park to Libby take note of these scenic lakes and earmark them for a future visit. A few small convenience-style stores can be found in the lakes area, but most services are some distance away. Some of the resorts offer cafes and minimum supplies.

This is the perfect place to spend a few relaxing days or a week fishing, paddling, swimming and enjoying the wildlife. Make sure to plan Thompson Chain of Lakes for your next Montana vacation. Spend a few lazy days on a sunny deck in front of a guest cabin or in a short-term vacation rental. A cooling dip on hot days, a bonfire along the lakeshore after dark, s’mores, hot dogs or a pleasant glass of wine-just think of the enjoyment you will encounter at Thompson Chan of Lakes. . . . and those trout and mackinaw are waiting!

Statistics lister are for Middle Thompson Lake only.

Things to do at Thompson Chain of Lakes

  • Vacation Rentals
  • Fishing
  • Fishing Tournaments
  • Ice Fishing
  • Boating
  • Swimming
  • Beach
  • Canoeing
  • Kayaking
  • Water Skiing
  • Camping
  • Campground
  • Picnicking
  • Cabin Rentals
  • Hiking
  • Biking
  • Wildlife Viewing
  • State Park
  • National Park
  • National Forest

Fish species found at Thompson Chain of Lakes

  • Bass
  • Black Bass
  • Brook Trout
  • Brown Trout
  • Cutthroat Trout
  • Largemouth Bass
  • Mackinaw Trout
  • Northern Pike
  • Perch
  • Pike
  • Pumpkinseed
  • Rainbow Trout
  • Smallmouth Bass
  • Sunfish
  • Trout
  • Whitefish
  • Yellow Perch

Thompson Chain of Lakes Photo Gallery

Thompson Chain of Lakes Statistics & Helpful Links

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Lake Type: Natural Freshwater Lake, Not Dammed

Surface Area: 557 acres

Normal Elevation (Full Pond): 3,398 feet

Average Depth: 55 feet

Maximum Depth: 160 feet

Trophic State: Mesotrophic

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Trophic State | LakeLubbers

Trophic State measures the level of algae and nutrients in a lake.

An oligotrophic lake is very clear (blue in color) and does not support much plant or fish life. A hyper-oligotrophic lake is the clearest of all lakes, and is nearly devoid of plants and fish.

A mesotrophic lake is slightly green and supports a moderate degree of plant and fish life. A lake's most desired trophic state is generally this mid-point - the mesotrophic state.

A eutrophic lake is somewhat murky and supports a large amount of plant and fish life. A hypereutrophic lake is clouded with algae, plant life, and fish life. A eutrophic or hyper-eutrophic lake can be difficult to navigate by boat - and is often an unpleasant place to swim.

The use of phosphorus-rich and nitrogen-rich fertilizer on lawns and golf courses surrounding a lake can cause it to become eutrophic or hypereutrophic.


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Catchment or Drainage Area | LakeLubbers

This is the surrounding area that drains into a lake, including land, rivers and their tributaries. This is also known as the lake's "catchment basin".

Small lakes at the highest peaks of mountains have small drainage areas. The world's oceans have the largest drainage areas.


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Lake-Area Population | LakeLubbers

This is the estimated number of people who live in a house with a view of a lake, plus those who self-describe the lake as their home, for example: "I live at Smith Mountain Lake."


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Water Residence Time | LakeLubbers

This is the estimated time that it takes for an amount of water equal to the entire volume of a lake to flow out of - or evaporate from - the lake.

Residence Time can be as short as a few days for fast-flowing small lakes, and can exceed 100 years for slow-flowing large lakes.


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Completion Year | LakeLubbers

This is the year that a reservoir was first filled to the reservoir's normal elevation - or the year that a natural lake was first dammed. A large reservoir can take more than a year to fill after its dam is first closed.

The Grand Anicut in southern India is generally considered the world's oldest dam that still operates. Grand Anicut was constructed in the second century BC. It now impounds an irrigation network that includes roughly one million acres.

You can find many of the the world's newest reservoirs on LakeLubbers. Many of the world's oldest reservoirs appear on the last page of that list.


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Water Volume | LakeLubbers

This is the estimated volume of water that a lake contains -- measured at the lake's normal elevation. By this measure, the world's largest freshwater lake is Siberia's Lake Baikal.

You can find many of the the world's largest lakes (by water volume) on LakeLubbers.

Water Volume can be measured in acre-feet, in cubic miles, or in cubic kilometers. One acre-foot is the amount of water needed to cover one acre (43,560 square feet) to a depth of one foot. One cubic mile equals 3,379,200 acre-feet. One cubic kilometer equals 810,713 acre-feet.

1 acre-foot is equal to 325,851 US gallons. Siberia's Lake Baikal contains about 6,276,367,740,000,000 gallons of freshwater - nearly 1 million gallons for every living person on earth.

The other - and more widely used - measure of a lake's size is the lake's surface acreage. By that measure, the world's largest freshwater lake is North America's Lake Superior.


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Maximum Depth | LakeLubbers

This is the estimated greatest depth of the water in a lake -- measured at the lake's normal elevation. The world's deepest lake is Siberia's Lake Baikal; that lake's maximum depth is estimated at 5,314 feet.

You can find many of the the world's deepest lakes on LakeLubbers. If you select the last page of that list, you will find the (maximum depth of) the shallowest lakes in our database.


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Average Depth | LakeLubbers

This is the estimated average depth of the water in a lake -- measured at the lake's normal elevation. If the water volume and surface area of a lake are known, an estimate of the lake's average depth can be calculated:

Water volume ÷ Surface Area = Average Depth

Example: 1,000,000 acre-feet ÷ 20,000 acres = 50 feet average depth


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Maximum Elevation | LakeLubbers

This is a lake's highest water level, measured by the lake's surface distance above sea level, that can occur during flooding. A lake's highest possible maximum elevation is usually the top of the lake's dam or spillway.

At lakes that include residential development, government regulations usually forbid the construction of homes below a lake's maximum elevation.


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Minimum Elevation | LakeLubbers

This is a lake's lowest water level, measured by the lake's surface distance above sea level, that can be reasonably expected to occur. Low lake levels can occur due to deliberate seasonal draw downs for irrigation or impending snow melt, reduced water inflows, drought and evaporation, residential or commercial water demands, and hydropower generation.

Some lakes' minimum and maximum elevations are virtually the same. Lakes that generate hydropower may vary by several feet - according to power demand. Lakes whose primary purpose is to prevent flooding can seasonally vary by 100 feet or more.

When some lakes reach their minimum elevation, their boat ramps may not be long enough to permit boat access - and boats docked on shallow parts of the lake may end up on dry ground. In those cases, kayakers and shore-based anglers may be among the few happy recreational users of the lake.


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Normal Elevation | LakeLubbers

This is a lake's normal water level, measured by the lake's surface distance above sea level. For a reservoir, this water level is also known as "full pond" or "full pool".

You can find many of the world's highest-elevated lakes on LakeLubbers. Lakes with the lowest elevations (known by LakeLubbers) are shown on the final page of that list.


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Shoreline Length | LakeLubbers

This is the length of the exterior shoreline around a lake - measured at the lake's normal elevation. The shoreline length can be considerably shorter or longer when lake water levels are lower or higher than normal.

A lake with many coves has a much longer shoreline than a lake of similar surface area that is nearly circular in shape.

When known, the shoreline miles that we report in our statistics include only the lake's exterior shoreline, and exclude the shorelines of islands located within a lake's boundaries. In lakes with many islands, those islands' combined shorelines may exceed a lake's exterior shoreline.

You can find many of the world's longest-shoreline lakes on Lakelubbers.


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Surface Area | LakeLubbers

This is the area (acreage, square kilometers, etc.) of the top surface area of a lake - measured at a lake's normal elevation. The surface area can be considerably smaller or larger when lake levels are lower or higher than normal. North America's Lake Superior is the world's largest freshwater lake by this measure.

The other measure of a lake's size is the lake's water volume. By that measure, the world's largest freshwater lake is Lake Baikal in Siberia.

You can find many of the world's largest lakes (acres) on Lakelubbers. There is no widely-accepted minimum surface area that defines a lake. What Lakelubbers describes as a lake, you might call a pond. The smallest lake that Lakelubbers currently includes is Hawaii's 2-acre Lake Waiau.


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Water Level Control | LakeLubbers

This is the organization that controls water releases or outflows from the lake or reservoir. In the USA, this is often the US Army Corps of Engineers, a power company, a municipal water system, an irrigation district, or a paper manufacturing company. In the case of private or gated lakes, a homeowners' association may be the lake's controlling authority.

Many lakes cross borders, including North America's Great Lakes. The control of such lakes and their coveted freshwater may be amicably shared - or hotly disputed.

"Water wars" continue at many lakes as growing populations and crop irrigation needs compete for the freshwater that lakes contain.


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Lake Type | LakeLubbers

There are 3 basic types of lakes that are currently included on LakeLubbers. 2 types may be dammed or not dammed, producing 5 classifications.

- A Reservoir is a man-made freshwater lake that is usually created by damming rivers.

- A Natural Freshwater Lake occurs naturally - often by glacial activity - and has a salinity of less than 30 parts per thousand. It may be dammed to produce electricity or for other reasons.

- A Natural Saltwater Lake occurs naturally and has a salinity of more than 30 parts per thousand (ppt). It may be dammed.

"Brackish" water may be categorized as freshwater or saltwater, depending on its salt content (salinity). Oligohaline water has less than 15 ppt of salt. Mesohaline water has 15-29 ppt. Polyhaline has 30-335 ppt.


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