Lake Koshkonong, Wisconsin, USA

Lake Locations:

USA - Midwest - Wisconsin - Southern Savanna Region -

Sprawled across southern Wisconsin, just a few miles down the Rock River from Fort Atkinson, Lake Koshkonong is a fantastic place to boat and fish. The Southern Savanna Region lake has a rich history, plentiful wildlife and thousands of acres of beautiful water to draw visitors from all over.

Formed by the construction of the Indianford Dam in 1846, Lake Koshkonong is a large shallow lake with a maximum depth of only seven feet. It is an impoundment of the Rock River which makes up both the inflow and outflow of the lake. The lake stretches across parts of Dane, Jefferson, and Rock Counties in southern Wisconsin. Before the construction of the dam the area now covered by the lake was part of a very large rice field with water so shallow and rice so thick it looked more like a meadow than a lake. Accounts written at the time describe millions of ducks landing in the field to eat the rice, at times almost covering the sun and darkening the sky. Occasionally horses and their riders got turned around and even lost in the huge field.

Clouden and Luke Stoughton built Indianford Dam to operate a sawmill raising water levels and expanding the surface area of Lake Koshkonong to 10,460 acres. By the early 1900’s higher water levels and invading hungry carp had killed most of the vegetation and rice. The wooden Indianford Dam was replaced with a concrete dam in 1917, and by 1929 it was owned by Wisconsin Power and Light Company who rebuilt it again in 1931. The dam generated power until 1961 when it became cost prohibitive to do so. In 1965 Wisconsin Power and Light Company transferred ownership of Indianford Dam to Rock County.

In 1974, there was an attempt by several Wisconsin power companies to build a nuclear power plant at Lake Koshkonong, but the proposal was denied because the lake is so shallow it was feared the plant would run out of water during drought years. Because three counties benefit from the lake, figuring out who was responsible for the dam became an issue and the dam suffered damage because of lack of maintenance. The Rock-Koshkonong Lake District (RKLD) was established and imbued with the power to levy taxes to protect and maintain Lake Koshkonong. The Wisconsin Department of Natural Resources controls the water levels on the lake and draws the water down slightly in the winter. The Rock-Koshkonong Lake District appealed to the Wisconsin DNR to raise lake levels seven inches and eliminate the winter draw down, but their request was denied. Proponents of the surrounding wetlands believe increasing the water levels would permanently damage surrounding wetland habitat and threaten the species of plants and animals that make it their home.

The Wisconsin DNR stocks Lake Koshkonong, and the lake is full of fish. There are healthy populations of perch, channel catfish, bluegill, crappie, largemouth bass, smallmouth bass and white bass. In the winter, anglers can ice fish, and the walleye are abundant. Even with its shallow depth the lake is a great place to boat, and there is plenty of room for power boats, pontoon boats and paddle boats along with sail boats and canoes. The lake is also popular with waterskiers and jet skiers.

Lake Koshkonong is named for Fort Koshkonong commanded by General Henry Atkinson during the Black Hawk War. Indian War Chief Black Hawk led the fight against the US Army for control of land in the Midwest. The fort lies in the present day town of Fort Atkinson. A visit to the reconstructed fort and charming town of Fort Atkinson is a great addition to a Lake Koshkonong getaway. Fort Atkinson has shops, restaurants, and various accommodations. For visitors who want to extend their stay, lakefront vacation rentals are available, and real estate is for sale in town and around the Lake Koshkonong shoreline.

Madison, Wisconsin’s capital and home of the University of Wisconsin, is about a 30-minute drive northwest of Lake Koshkonong. The Olbrich Botanical Gardens, located in Madison near the shore of Lake Monona, features 16 acres of outdoor gardens for leisurely strolling. Olbrich features a rose garden, a sunken garden, and a Thai pavilion and garden. The Bolz Conservatory houses indoor and holiday displays, including exotic plants, orchids, birds, and a waterfall.

With several groups including the RKLD watching over the water quality of Lake Koshkonong, it is sure to delight visitors far into the future. There is something to please everyone on beautiful Lake Koshkonong.

Things to do at Lake Koshkonong

  • Vacation Rentals
  • Fishing
  • Boating
  • Sailing
  • Canoeing
  • Jet Skiing
  • Water Skiing
  • Horseback Riding
  • Waterfall
  • Wildlife Viewing
  • Birding

Fish species found at Lake Koshkonong

  • Bass
  • Black Bass
  • Bluegill
  • Carp
  • Catfish
  • Channel Catfish
  • Crappie
  • Largemouth Bass
  • Perch
  • Smallmouth Bass
  • Sunfish
  • Walleye
  • White Bass

Lake Koshkonong Photo Gallery

Lake Koshkonong Statistics & Helpful Links

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Lake Type: Artificial Reservoir, Dammed

Water Level Control: Wisconsin Department of Natural Resources

Surface Area: 10,460 acres

Shoreline Length: 27 miles

Normal Elevation (Full Pond): 776 feet

Minimum Elevation (Min Pond): 774 feet

Maximum Elevation (Max Pond): 780 feet

Average Depth: 5 feet

Maximum Depth: 7 feet

Water Volume: 55,792 acre-feet

Completion Year: 1846

Water Residence Time: 15.6 days

Lake Area-Population: 11,621

Drainage Area: 2,300 sq. miles

Trophic State: Eutrophic

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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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