Discover the Largest Dam in Wisconsin (And What Lives in the Waters Behind It)

Petenwell Hydroelectric Dam
© iStock.com/jferrer

Written by Kaleigh Moore

Updated: July 27, 2023

Share on:

Advertisement


Wisconsin boasts several exceptional dams that not only do an important job of regulating water flow but also attract droves of tourists. The Petenwell Dam tops them all; this engineering masterpiece is Wisconsin’s largest artificial inland body of water and stands at a whopping 44 feet high! Keep reading to learn more about this mind-blowing marvel.

The Petenwell Dam: the Largest Dam in Wisconsin

The Petenwell Dam spans over 23,040 acres. It’s the second-largest inland body of water in Wisconsin. The dam was built in the late 1940s solely for flood control and hydroelectric power generation. 

Its flowage is located on Wisconsin’s Central Plain, or Central Sand, which used to be the bed of Glacial Lake Wisconsin — a prehistoric one-million-acre body of water.

The Petenwell Dam and the Castle Rock Dam are unique because they were the first in the US to be built on sand. These concrete dams are classified as “floating-type construction” because they have embedded cutoff walls that anchor them securely in the glacial sands. 

Before the Petenwell Dam was built, the lake bed consisted of farmland, forested knolls, and prairie, and the Wisconsin River meandered through it. 

Petenwell is a shallow lake, and windy days can cause turbulence. The bottom of the lake is inconsistent, with varying depths. Anyone planning to boat on the lake should consult the map beforehand to become familiar with the area.

Rocky Shoreline:  Large boulders help to form a side of Petenwell Lake in central Wisconsin.

Before the Petenwell Dam was built, the lake bed consisted of farmland, forested knolls, and prairie, and the Wisconsin River meandered through it.

©Earl D. Walker/Shutterstock.com

Before the Petenwell Dam was built, the lake bed consisted of farmland, forested knolls, and prairie, and the Wisconsin River meandered through it. 

The Wisconsin River: From Source to Merging with Mississippi

The Wisconsin River originates in the Lac Vieux Desert on the border of Wisconsin and Michigan. It flows 500 miles across the state, falling over 1,000 feet in altitude before merging with the Mississippi River in Prairie du Chien.

For thousands of years, the river has carved out gorges, rapids, and waterfalls during the Ice Age, but now, the noise of these natural wonders has been replaced by the buzzing of 26 hydroelectric dams. These generate a significant amount of energy annually, which could power every household in Madison for an entire year.

The Wisconsin River has had severe flooding issues, but now 21 reservoirs help manage it. Before spring runoff starts, many of these reservoirs are lowered to prepare for the anticipated high water.

Colorful autumn trees reflecting off of the Wisconsin River in Merrill, Wisconsin, panorama

The Wisconsin River flows 500 miles across the state, falling over 1,000 feet in altitude before merging with the Mississippi River in Prairie du Chien.

©Michael Tatman/Shutterstock.com

Primary Fish Species Residing In Petenwell Lake

There are numerous types of fish to catch at Petenwell Flowage, Wisconsin, but here are the most popular species:

Northern Pike

The northern pike is a fish that can reach up to 50 inches long and must be at least 32-40 inches long to be caught legally. Its skin has light-colored marks on a dark background and multiple teeth. Typically, this fish weighs between 2-5 pounds. You can find them in various places, including rivers, lakes, ponds, streams, and slow-moving water with many weeds.

Northern pikes spawn and become sexually mature from late March to early April in flooded regions with plenty of vegetation. They lay between 8,000 to 100,000 eggs and usually reach sexual maturity after 3-5 years. Northern pikes eat anything small enough to fit in their mouth, including other pikes. They can live up to 24-26 years but have many predators, like humans, larger pikes, and silver and sea lampreys.

Great places to catch northern pike include Petenwell Lake, Mississippi River, Lake Superior, and Lake Michigan. Anglers often use live fish bait or wobbling spoons to lure them. In Wisconsin, the largest northern pike ever caught weighed 38 pounds and was netted on August 6, 1952, in Lake Puckaway. The biggest northern pike ever caught in history weighed 55 pounds 1 ounce. It was caught in Lake of Grefeern, Germany, on October 16, 1986.

Freshwater fish Northern pike (Esox lucius) in the beautiful clean pound. Underwater shot with nice bacground and natural light. Wild life animal.

You can find northern pikes in various places, including rivers, lakes, ponds, streams, and slow-moving water with many weeds.

©Rostislav Stefanek/Shutterstock.com

Interesting fact: Northern pikes don’t provide parental care for their young; usually, the females are larger than the males. When they’re starving, these fish can even consume a full-grown muskrat. The ideal moment to catch them is immediately after ice formation on the lakes.

Largemouth Bass

The Centrarchidae family includes the largemouth bass. It has a dark green back and head, a stripe from nose to tail base, and streaks on its head. Typically, it measures 14 inches long and weighs 2-3 pounds. This fish prefers warm, shallow waters, including weedy lakes and calm rivers. From late April to early July, males protect their 5,000 eggs until they hatch at 60-degree water temperature. Largemouth bass mature at three years old.

The largemouth bass feeds on crayfish, small fish, insects, and frogs. Its lifespan can reach 13 years, but it’s prone to predation from bigger fish, humans, and others. This species is also found in Lake Michigan, the Mississippi River, and Lake Superior. Live bait is highly effective for fishing this species. Additionally, there are organized fishing contests.

The biggest largemouth bass caught in the state weighed 11 pounds 3 ounces. It was captured at Ripley Lake on October 12, 1940. The largest one ever caught worldwide was 22 pounds 4 ounces — caught at Montgomery Lake, GA, on June 2, 1932. The largemouth bass goes inactive during winter. It’s the biggest sunfish in the southwest.

Big Bass Largemouth - Fishing

The largemouth bass feeds on crayfish, small fish, insects, and frogs but it’s prone to predation from bigger fish, humans, and others.

©Pierre Rebollar/Shutterstock.com

Muskie, Musky, or Muskellunge

Muskie is a fish from the Esocidae family. It has a silver body with dark markings, a flat nose, and a large mouth with strong teeth. Its muscles are stiff, and it weighs around 40 pounds with a length of approximately 40 inches. Muskellunge inhabit lakes, rivers, and deep pools with slow-moving water. They lay eggs along shorelines and spawn from mid-April to mid-May when the water temperature is approximately 55 degrees Fahrenheit. 

They don’t engage in parental care and can lay up to 225,000 eggs. Sexual maturity is attained between 5 to 7 years of age.

Muskellunge eat fish like muskies and animals like frogs, mice, ducks, and muskrats. They live for 8-10 years and are hunted by humans, other muskies, and big birds. People often use plugs, spoons, bucktails, and live fish bait to catch them.

Muskellunge are aggressive eaters and tend to revisit their spawning area annually. The highest recorded weight for a muskellunge caught in the state is 69 pounds 11 ounces, caught at Chippewa Flowage on October 20, 1949, and the world record is 70 pounds, caught at Eau Claire Lake, Wisconsin, on June 6, 1954. It takes around 50 hours on average for an individual to catch a muskie that meets the legal size requirement.

A muskie fish caught by a fisher

Muskie is a fish from the Esocidae family that has a silver body with dark markings, a flat nose, and a large mouth with strong teeth.

©M Huston/Shutterstock.com

Channel Catfish

Petenwell Lake has plenty of channel catfish. They’re part of the Ictaluridae family and have a blueish-black hue, a slim head, eight barbels, and a forked tail. These fish can grow up to 60 pounds, and their whiskers surround their mouth. 

They usually measure between 12-20 inches. channel catfish thrive in cloudy water and prefer living in lakes, ponds, and rivers. They become sexually mature at 4-5 years old, around June and July when the water is roughly 75 degrees Fahrenheit. During this time, they can lay between 3,000-30,000 eggs.

Channel catfish are opportunistic feeders who consume various items such as plants, fish, and garbage. They have a lifespan of up to 20 years and can fall prey to bigger freshwater fish and people. These fish are abundant in the lower two-thirds of the state and can be found in larger rivers like the Wisconsin River. Anglers often use hoop nets and trotlines to catch channel catfish by hand because they dislike artificial baits.

The biggest channel catfish ever caught in Wisconsin’s river in 1962 was 44 pounds. Meanwhile, the world record is 58 pounds from South Carolina’s Santee-Cooper Reservoir, caught on July 7, 1964. Male channel catfish protect their offspring until they can fend for themselves. They are more plentiful than flathead catfish but often confused with blue catfish, a frequently farmed species in the US.

Channel catfish, Ictalurus punctatus, freshwater predator in European biotope fish aquarium

Channel catfish are abundant in the lower two-thirds of the state and can be found in larger rivers like the Wisconsin River.

©Aleron Val/Shutterstock.com

Walleye

The walleye is a type of fish found in Petenwell Lake. It is scientifically known as Stizostedion vitreum and is part of the Percidae family. This fish is golden, can reach up to 37 inches long, and weigh 25 pounds on average. Its tail fin has a white tip, and its eyes are large. Walleyes prefer to live in big rivers and clear-water lakes. They reach sexual maturity at 2-5 years old and spawn in 50-degree water temperatures from mid-April to early May. Walleyes don’t provide parental care and can lay up to 495,000 eggs.

The walleye’s diet mainly comprises of smaller fish, and young ones feed on plankton. It can survive for up to 15 years but faces dangers from bigger fish, humans, and large birds. Other places known for walleye fishing are Lake Superior, Lake Michigan, and the Mississippi River. Popular bait options for walleye fishing include worms, leeches, small plugs, and minnows.

The biggest walleye caught in the state weighed 18 pounds from High Lake in 1933. A larger one of 25 pounds was caught in Old Hickory Lake in TN in 1960, which is the world record. The walleye, part of the perch family, is the most valuable game fish in the state and can grow quite large. It likes to eat at dawn and dusk and has night vision.

Walleye fish closeup held over the water

Known scientifically as

Stizostedion vitreum

, walleye fish can reach up to 37 inches long, and weigh 25 pounds on average.

©Harlan Schwartz/Shutterstock.com

Panfish

Petenwell Lake has plenty of panfish, a species that reproduces rapidly and is commonly used for food in Wisconsin. Bluegills tend to cluster together and remain near their food supply. Pumpkinseed fish thrive in clear lakes with vegetation on the bottom and are named for their appearance. Rock basses are common in Wisconsin’s rocky-bottomed rivers and streams and are popular for eating. 

People come from far and wide to Wisconsin to catch its excellent panfish. Local restaurants often serve yellow perch for fish fries. They can be caught using worms, minnows, and insects. To locate a place teeming with panfish, seek out waterbodies between 1-10 feet deep.

Bluegill or Brim freshly caught is laying on a grass background

Meet the Bluegill: A popular freshwater fish known for its vibrant colors, feisty nature, and delicious taste.

©dcwcreations/Shutterstock.com

Sturgeon

Sturgeon belongs to the Acipenseridae family. They usually inhabit temperate waters; some migrate to rivers annually to spawn. A small number of sturgeon species can be found only in Petenwell Lake. Some sturgeon eggs are used to make caviar. Sadly, most sturgeon species are in critical danger. Fishing for sturgeon is prohibited in Petenwell Lake.

Sturgeon fish

Most sturgeon species are in danger of extinction owing to the wide consumption of their eggs.

©azure1/Shutterstock.com

Paddlefish

This primitive freshwater fish has a special snout shaped like a paddle, smooth skin, and a skeleton made of cartilage. It is part of the same family as sturgeons, known as Polyodontidae. Paddlefish have a unique way of feeding. They open their mouth wide and filter plankton from the water using their gill rakers.

The American paddlefish weigh up to 40 pounds — often gray or greenish. Occasionally, these fish can grow to be 7 feet long and weigh 200 pounds. The IUCN (International Union for Conservation of Nature) has deemed them vulnerable, so fishing for them in Petenwell Lake is prohibited.

The paddlefish is a primitive freshwater fish that has a special snout shaped like a paddle

The paddlefish is a primitive freshwater fish that has a special snout shaped like a paddle, smooth skin, and a skeleton made of cartilage.

©AndresDica/Shutterstock.com

Where is The Petenwell Dam Located on a Map?

The Petenwell Dam is located on the Wisconsin River just 12.3 miles from Adams, in Juneau County, Wisconsin, near Strongs Prairie, and twenty miles north of Necedah.

Neatly tucked away in central Wisconsin, Lake Petenwell is a man-made reservoir positioned on the Wisconsin River. The lake spans across Adams, Juneau, and Wood counties, adjacent to Castle Rock Lake. Encompassing an expansive area of over 23,000 acres, Lake Petenwell reaches a depth of 42 feet. Notably, it holds the distinction of being Wisconsin’s second-largest lake, covering approximately 23,040 acres or roughly 36 square miles.

Here is The Petenwell Dam on a map:

A Guide to Fishing Regulations on Petenwell Lake

Fishing in Petenwell Lake is subject to regulations. You can fish all year long using hook and line, except for certain species such as muskellunge and endangered species. Using motor trolling is permitted, but each angler can only have up to 3 lures, hooks, or baits.

  • Catfish: You can fish for this species all year long in Petenwell Lake. There’s no minimum size requirement, and you can catch up to 10 in a day.
  • Bass: You can catch largemouth and smallmouth bass any time of the year, but they must be at least 14 inches long if you want to keep them. You are only allowed to keep a maximum of five per day.
  • Muskellunge: Starting May 6, 2023, until December 31, 2023, you can fish for muskellunge and hybrids. You can only catch one daily, and they must be at least 50 inches long.
  • Northern Pike: September and October are the best months to fish for pike. Also, the daily bag limit is one for this species, and they must be at least 32 inches long.
  • Panfish: Panfish like bluegill, yellow perch, sunfish, pumpkinseed, and crappie are catchable throughout the year. There are no size restrictions, and you can catch up to 25 panfish daily.
  • Walleye: You can catch Walleye, sauger, and hybrids every day, all year round. The fish you catch must be at least 15 inches long, but if it’s between 20 and 28 inches, you must put it back into the water. You can only keep one if you catch a fish over 28 inches. You’re not allowed to keep more than five fish per day.

Here Is A Table Summarizing Fishing Regulations For Petenwell Lake:

SpeciesSeasonSize LimitBag Limit Per Day
CatfishAll yearNone10
Largemouth and smallmouth bassAll year14″5
Muskellunge and hybridsMay 6 – December 3150″1
Northern pikeAll year32″1
Panfish (bluegill, yellow perch, sunfish, pumpkinseed, crappie)All yearNone25
WalleyeAll year15″ (20″-28″ must be released)5

Wrap-Up: Wisconsin’s Largest Dam and the Rich Biodiversity of Its Backwaters

The Petenwell Dam, a towering structure that reaches 44 feet in height, is the biggest human-made lake in Wisconsin. It was built to prevent floods and create hydroelectricity. The dam covers a vast area of around 23,040 acres on Wisconsin’s Central Plain. One peculiar fact about this dam is that it was constructed on sand, making it an exceptional feat of engineering.

Before its construction, the area combined farmland, forested knolls, and prairie, with the Wisconsin River meandering through it. The Wisconsin River begins at Lac Vieux Desert. It stretches for 500 miles across the state and drops over 1,000 feet in elevation before merging with the Mississippi River in Prairie du Chien. The Petenwell Flowage is a habitat for various fish species, including northern pike, largemouth bass, and muskellunge, that anglers typically catch using live bait or wobbling spoons.


Share this post on:

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.