John Martin Reservoir, Colorado, USA

Lake Locations:

USA - West - Colorado - Southeast -

Standing among the large boulders on the gravel shore watching bald eagles soar over the water, it’s easy to believe that John Martin Reservoir is an oasis in the surrounding high desert prairie. Abundant wildlife, good fishing, and a rich history add to the lure of this relatively remote western treasure.

Situated halfway between Las Animas and Lamar, John Martin Reservoir is the largest body of water (by surface area) in southeast Colorado. The reservoir was created as an irrigation and flood control project by the U.S. Army Corps of Engineers by building the John Martin Dam across the Arkansas River. The dam’s history is as rich as that of the rest of the region. Originally called the Caddoa Project, the dam was started in 1936 by the Corps of Engineers. It was only about 85 percent complete when construction was stopped because of World War II. The Corps finished the dam in 1948, but before its completion it was renamed the John Martin Dam and Reservoir to honor the late John A. Martin.

Mr. Martin was a congressman who served his state for more than ten years. Repeated flooding in the Arkansas River Valley led him to push for legislation to approve the dam project. He was also part of passing the Social Security Act, and is remembered as a great humanitarian. Today the US Army Corps of Engineers manages the dam and reservoir, but the recreation areas and campgrounds are under the control of the Colorado State Park system.

Flooding hasn’t been an issue in recent years, however, just the opposite is true. Lake size is highly variable, ranging from 2,000 to 17,000 acres, depending on rainfall/snowfall and irrigation water withdrawals. Average depths range from five to 10 feet, 30 to 50 feet at the dam. Reservoir levels have stayed low for several years. In fact, the U.S. Army Corps of Engineers bought 2,000 acre-feet of water from Colorado Springs to protect the reservoir’s fish populations. The project was successful, and fishing on the reservoir is good.

Anglers can fish from the shore or boat for walleye, crappie, perch, and catfish. The bass fishing is particularly good, and because the lake isn’t crowded, the bass have not been over-fished. Lake Hasty, just below the John Martin Dam, is periodically stocked with trout. It also has the only designated swimming area. One interesting side effect of the low reservoir levels is the 2002 discovery of fossilized dinosaur tracks. Park rangers found 79 tracks in two separate locations. More dinosaur tracks can be found within 100 miles of the reservoir in the Canyonlands of the Comanche National Grasslands.

Dinosaurs may be the oldest residents of the Arkansas River Valley, but they certainly weren’t the only ones. Native Americans wintered in the valley. Downstream from the dam the “Big Timbers” area, named because it was historically covered with large cottonwood trees, provided shelter and good hunting for the native people. Beside the reservoir in the John Martin Reservoir State Park, the Red Shin Trail is named for a Cheyenne warrior whose tribe lived in the area in the early 1800’s. Local legend says that the warrior named Red Shin fought with another warrior over a maiden. Red Shin armed himself and was able to hold off his attackers. Since then, the Dakota Sandstone formation has been called Red Shin’s standing ground. The 4.5 mile long trail starts below the dam and winds past Indian carvings. It also offers ample opportunities to see wildlife and the reservoir.

The trail ends at a marker for another historically significant trail. The Santa Fe Trail, which brought immigrants west before the railroad arrived, ran through the area. A section of the trail from Las Animas to Hasty is preserved for visitors to see.

In addition to the area’s rich history, visitors to the reservoir can also enjoy watching the 373 species of birds that make their homes at John Martin Reservoir. Bald and golden eagles winter there and the shoreline is one of the few remaining nesting areas in Colorado for the federally protected Least Tern and Piping Plover. There is plenty of wildlife at the reservoir and state park, but there is no hunting. Hunters can use the campgrounds as base camp, however, and find exceptional hunting within a five minute drive of the reservoir. Boaters will find plenty of room on the uncrowded lake, and there is jet skiing, water skiing, and sailboarding. There is no marina, but there is a small retail shop and visitor center.

With southeastern Colorado’s mild weather, the reservoir’s wildlife, beautiful open water and the area’s fascinating history, everyone will find something to love at John Martin Reservoir and State Park.

Things to do at John Martin Reservoir

  • Fishing
  • Boating
  • Swimming
  • Jet Skiing
  • Water Skiing
  • Camping
  • Campground
  • Hiking
  • Hunting
  • Wildlife Viewing
  • Birding
  • State Park

Fish species found at John Martin Reservoir

  • Bass
  • Catfish
  • Crappie
  • Perch
  • Trout
  • Walleye

John Martin Reservoir Photo Gallery

John Martin Reservoir Statistics & Helpful Links

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Lake Type: Artificial Reservoir, Dammed

Water Level Control: US Army Corps of Engineers

Surface Area: 9,503 acres

Shoreline Length: 22 miles

Normal Elevation (Full Pond): 3,815 feet

Minimum Elevation (Min Pond): 0 feet

Maximum Elevation (Max Pond): 3,852 feet

Average Depth: 7 feet

Water Volume: 66,000 acre-feet

Completion Year: 1948

Drainage Area: 18,913 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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