Henrys Lake, Idaho, USA

Lake Locations:

USA - West - Idaho - Eastern -

Also known as:  Henry's Lake Reservoir

Hidden in the far north corner of Eastern Idaho, just over the border from both Montana and Wyoming, Henrys Lake attracts thousands of visitors every year. At approximately 6500 acres, Henrys Lake is a natural lake formed by glaciers and fed by several inflowing streams and springs. Less than 10 miles from the Continental Divide, Henrys Lake is the headwaters of Henrys Fork – famed tributary to the Snake River. It is also home to some of the best trout fishing in the West. A dam built for irrigation purposes across the outlet in 1923 enlarged Henrys Lake a little, but the same excellent fishing and spectacular mountain vistas have existed since long before Missouri Fur Company explorer Major Andrew Henry first saw the lake. Several Native American tribes predated him in their enjoyment of the lake, but the high altitude and winter snows likely made the site only a seasonal camping ground. Only 15 miles west of Yellowstone National Park, Henrys Lake is a common stop for park visitors who want to get in some trout fishing before the end of vacation.

Henrys Lake averages 12 feet in depth, which is unusual for a lake of this size. The lake produces a healthy crop of vegetation each summer, making for ideal habitat for a number of fish. Lying across a large flat valley, Henrys Lake is surrounded by majestic mountains such as Black Mountain, Mount Jefferson and Sawtell Peak in the Centennial and Henrys Lake ranges. Views from the lakeshore are spectacular from nearly every vantage point. Much of the lakeshore is in private hands,but several campgrounds, RV parks and private ranch resorts dot the shoreline. Both a state park and a county park offer boat launch access, although water skiing and power boating don’t seem to be the norm here. Several wetland areas along the shores shelter a wide variety of birds, waterfowl and wildlife. A few developments hold much of the private housing, and isolated lodge-style homes occupy a few of the points jutting into the lake. The atmosphere at Henrys Lake therefore remains serene, and local groups are determined to protect its pristine nature.

Henrys Lake State Park on the south side extends along the Henry’s Fork outflow, still a shallow trout stream this far upriver. Forty-four campsites are offered here, with a few more available at the Frome County Park on the northwest bank. There is no organized swim area; more visitors engage in canoeing, kayaking and small boating than anything else. And much of that boating involves getting to the hottest trout fishing spots, the lake’s most famous draw. Boat permits and invasive species stickers are required for most boats. The stickers pay for the several boat wash stations around the lake as protection against invasive species. Henrys Lake holds a native population of the endangered Yellowstone species of cutthroat trout, a population jealously guarded from possible extinction by judicious fishery management. Henrys Lake Fish Hatchery and Fish Management Station, the oldest hatchery in the state, breeds hybrid trout along the northeast shore to plant both in Henrys Lake and in other lakes in the area. By making the sterile hybrids available in the lake, fishing pressure on the native Yellowstone cutthroat is reduced.

As a trout fishery, Henrys Lake is world-famous. Trout spawn in the many inlet streams and grow rapidly fat in the productive lake. Catching trout above five pounds is the norm here. Besides the Yellowstone cutthroat trout, brook trout, rainbow trout and rainbow hybrid trout are often caught via fly-fishing. There was once a population of mountain whitefish in the lake, but these fish have not been observed in several years. Along with the introduced rainbow and brook trout, the Rocky Mountain sculpin, red-sided shiner and a few other non-native species have been found to inhabit the lake. The Henrys Lake Foundation works with the Idaho Dept. of Fish and Game to improve habitat for the trout. Recently, they have installed appropriate screening at the irrigation inlets of the tributary streams where the trout spawn to prevent them from ending up in the irrigation systems. Although Henrys Lake isn’t in danger of too much water loss, the out-flowing Henry’s Fork must be carefully managed to assure adequate water during all seasons to facilitate trout spawning along the waterway. Because of the system of water rights, nearly all of the water in Henry’s Fork is allocated to irrigation; in dry years, very little is left for natural habitat. This is a problem the State of Idaho and conservation groups are actively working on to assure enough water for every need.

Fishing isn’t the only attraction at Henrys Lake. The 585-acre state park holds several trails for hiking. The 350-acre Bureau of Land Management Wildlife Study Area provides protected habitat for black bear, elk, moose, deer, and a variety of birds. Management of grizzly bear is given priority over other uses. The Henrys Lake area’s open grasslands and wetlands are critical habitat for peregrine falcons, gray wolves and bald eagles, and crucial habitat for large numbers of big game, waterfowl and sandhill cranes. White spruce, rare in Idaho, grows on soils believed to be remnants of floating islands recorded by early trappers who worked the area. Designated an Area of Critical Environmental Concern, the Bureau of Land Management manages 2415 acres near the lake. Henrys Lake is open for ice fishing in the winter, and snowmobile trails assure winter sports enthusiasts have plenty to keep them interested. Henrys Lake is surrounded by Caribou-Targhee National Forest. Along with Yellowstone National Park, the public lands nearby provide hundreds of miles of groomed trails for snowmobiling, cross-country skiing and hiking.

The tiny settlement of Lake lies along the highway on the east side of Henrys Lake, The lake is considered to be in the municipality of Island Park, further south on Henry’s Fork. Island Park lies next to the Island Park Reservoir, where Henry’s Fork is once again impounded. The town of only a few hundred people is actually measured as 33 miles long, mostly because of Idaho liquor laws which only allow liquor to be sold within city limits. So Island Park stretches to encompass the fishing resorts along Henrys Lake as a convenience for the tourism business. There is a regular chain hotel in Island Park for those who wish to fish both lakes, and several businesses that cater to campers and hikers with supplies, groceries and bait. The town of West Yellowstone is only 13 miles from Henrys Lake and offers more in the way of city amenities. West Yellowstone is the western gateway into Yellowstone National Park and is thus well-equipped with lodgings, restaurants, stores and services.

The area around Henrys Lake is filled with campgrounds, resorts and private rentals. All types of lodgings can be found to meet nearly every budget. Henrys Lake is located a hundred miles north of Idaho Falls and nearly the same distance south of Bozeman, MT; a small air strip also serves the area. One visit – and one monster trout in the landing net – and many visitors start looking for real estate in the area: some can usually be found not far from Henrys Lake. Won’t you come and try the fishing? It’ll be the trip of a lifetime!

Things to do at Henrys Lake

  • Vacation Rentals
  • Fishing
  • Ice Fishing
  • Boating
  • Swimming
  • Canoeing
  • Kayaking
  • Water Skiing
  • Camping
  • Campground
  • Hiking
  • Cross-Country Skiing
  • Snowmobiling
  • Wildlife Viewing
  • Birding
  • State Park
  • National Park
  • National Forest

Fish species found at Henrys Lake

  • Brook Trout
  • Carp
  • Cutthroat Trout
  • Rainbow Trout
  • Sculpin
  • Trout
  • Whitefish

Henrys Lake Photo Gallery

Henrys Lake Statistics & Helpful Links

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Lake Type: Not Known

Water Level Control: North Fork Reservoir Co.

Surface Area: 6,500 acres

Shoreline Length: 14 miles

Normal Elevation (Full Pond): 6,472 feet

Average Depth: 12 feet

Maximum Depth: 21 feet

Water Volume: 90,420 acre-feet

Completion Year: 1923

Drainage Area: 94 sq. miles

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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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