Over the years, I’ve discovered that when I speak of a flowage, many folks from outside the Upper Midwest have no idea what I’m talking about. This is especially true for people who live west of the Mississippi River. We can resolve this confusion very simply by first comparing a flowage to a more common term – a reservoir.
Reservoir is the term used to describe a man-made impoundment of water created by damming a river, thus causing a large lake or reservoir to back up behind the dam. The river that was dammed continues to flow at a moderated rate, through and below the dam. The reservoir exists above the dam. Reservoirs are common in the Western and Plain states. They are normally used in mountainous or flat, arid land to control flooding. The bottom content of reservoirs are normally sand, gravel, silt or rock.
A flowage is very similar to a reservoir. A flowage is also man-made and is formed by damming a river, thus causing a water impoundment to back up behind the dam. Several factors make flowages different from reservoirs. Flowages are common in the northern Midwest where woodlands and low terrain have been intentionally flooded, either to control flooding, to generate hydro-power, or to form a recreational area in a remote location, or all of the above. Once flooding is complete, the bottom of flowages often consists of brush, timber, natural lake basins, natural creek, stream, or river beds, rock, sand, or mud (mostly in the lake basins).
Follow the link below to see a detailed map of he Turtle Flambeau Flowage. Note the original lake basins, which are shaded in dark blue. Note the river and channels which connect the lake basins. These were the features of the land before this area was flooded. These features remain today, though they are under water.
Wisconsin has many flowages and few, if any, reservoirs. All of the flowages are popular recreational areas. The larger flowages are the famous Turtle-Flambeau Flowage in Iron County, which is a damming of the Flambeau River. The Rainbow Flowage in Oneida County is a damming of the Wisconsin River. The Willow Flowage in Oneida County is a damming of the Tomahawk River. The Chippewa Flowage in Sawyer County is a damming of the Chippewa River. The Gile Flowage in Iron County is a damming of the Montreal River. There are numerous smaller flowages throughout the northern part of the state.
The most popular recreation on the large flowages is fishing; whether that be on open water or through the ice in winter. My family confines our fishing to flowages. Why? Because flowages offer a wider variety and abundance of fish-holding structure versus lakes.
Think of a lake as a soup bowl. The shoreline gradually drops off and the water level becomes deeper as you move towards the center of the lake. Fish-holding structure may consist of shoreline weeds, occasional rock piles on the bottom, or a point, if there is an island in the lake. The water in Northwood’s lakes are generally gin-clear, allowing for light penetration to depths as much as 20 feet. This could allow for deeper weed bed growth if bottom content is suitable for plants. When compared to the huge flowages, lakes are relatively small with limited structure for holding fish. So they offer less opportunity for finding fish. Additionally, the clarity of the water is a problem.
On the other hand, large flowages are extremely diverse for bottom content. The natural lake basins, streams, creeks, and rivers that were flooded are all under water but easily located with a fish-finder’s LCD display. Flowages are dotted with hundreds of islands. Brush, stumps, and logs are everywhere with most being under water. The Turtle-Flambeau Flowage holds an abundance of rock with some underwater rocks being as big as a small auto.
Another characteristic of a flowage, versus a reservoir, is that the water is “stained”. The water in most reservoirs is clear, blue, or slightly green. The water in flowages is stained due to tannic acid. Tannic acid comes from decaying timber and flowages usually contain an abundance of decaying stumps and timber. Tannic acid is harmless, odorless, and clean. I’ve had guests say that the water is dirty; which it isn’t. Tannic acid in a body of water improves fishing because it decreases light penetration. Fish do not care for sun or light.
Hopefully, you now understand the difference between a flowage and a reservoir. A flowage is flooded low land or timber land. A reservoir is flooded high land or mountainous area. Note the photos of each that are contained within this post.
On my blog calendar, February is flowage month. In March, posts will focus on the topic of Places of Interest in the Northwoods. But before we leave the subject of flowages, you will soon find:
- How the Turtle Flambeau Flowage was created in 1926.
- Why the Turtle Flambeau Flowage has the reputation for being the most hazardous flowage to navigate in Wisconsin.
- Other big flowages in the Northwoods that are popular recreation spots.