Madum Lake is the largest lake in the Himmerland

Himmerland

Himmerland is a peninsula in northeastern Jutland, Denmark. It is delimited to the north and the west by the Limfjord, to the east by the Kattegat, and to the south by the Mariager Fjord. The largest city is Aalborg; smaller towns include Hobro, Aars, Løgstør, Støvring and Nibe...

 peninsula of Jutland

Jutland

Jutland , historically also called Cimbria, is the name of the peninsula that juts out in Northern Europe toward the rest of Scandinavia, forming the mainland part of Denmark. It has the North Sea to its west, Kattegat and Skagerrak to its north, the Baltic Sea to its east, and the Danish–German...

, Denmark

Denmark

Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

. The lake covers an area of ​​204 hectares (504.1 acre), and has a depth of 7.5 metres (24.6 ft) at its deepest point. It is both an important bird sanctuary and a popular bathing site for tourists.

Formation

The lake most likely developed out of a glacial kettle hole – a hollow formed by the melting of glacial ice left by the Quaternary ice age. The water in Madum Lake is reportedly very clear, but acidic and nutrient-poor.

Bird sanctuary

The lake is an important bird sanctuary, serving as a stopover for goldeneye

Goldeneye (duck)

Goldeneye are small tree-hole nesting northern hemisphere seaducks belonging to the genus Bucephala. Their plumage is black and white, and they eat fish, crustaceans and other marine life....

 and tufted duck

Tufted Duck

The Tufted Duck, Aythya fuligula, is a medium-sized diving duck with a population of close to one million birds.- Description :The adult male is all black except for white flanks and a blue-grey bill. It has an obvious head tuft that gives the species its name.The adult female is brown with paler...

s, and to a lesser extent, mallard

Mallard

The Mallard , or Wild Duck , is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand and Australia....

s. Spring and autumn guests at the lake include osprey

Osprey

The Osprey , sometimes known as the sea hawk or fish eagle, is a diurnal, fish-eating bird of prey. It is a large raptor, reaching more than in length and across the wings...

s, who forage on the lake's population of pike

Pike

-Transit:*Pike or toll road, a course in which fees are collected. Sometimes a historical name of what once was a toll road.-Fish:*Esox, genus of pikes**Northern pike, common north hemisphere pike*Blue pike or blue walleye, an extinct freshwater fish...

 and perch

Perch

Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke meaning spotted, and the...

. It furthermore serves as an important breeding site, hosting the nests of great crested grebe

Great Crested Grebe

The Great Crested Grebe is a member of the grebe family of water birds.- Description :The Great Crested Grebe is long with a wingspan. It is an excellent swimmer and diver, and pursues its fish prey underwater. The adults are unmistakable in summer with head and neck decorations...

s, mute swan

Mute Swan

The Mute Swan is a species of swan, and thus a member of the duck, goose and swan family Anatidae. It is native to much of Europe and Asia, and the far north of Africa. It is also an introduced species in North America, Australasia and southern Africa. The name 'mute' derives from it being less...

s and coot

Coot

Coots are medium-sized water birds that are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water...

s.

Surroundings

Today, the former heathland lake is surrounded by the Rold Skov

Rold Skov

Rold Skov is Denmark's second largest forest.The forest is named after the village of Rold which lies in the southern outskirt of the forest. Other towns in Rold Skov include Arden, Rebild and Skørping....

 forest. To the north of the lake is a narrow forested belt, with birch

Birch

Birch is a tree or shrub of the genus Betula , in the family Betulaceae, closely related to the beech/oak family, Fagaceae. The Betula genus contains 30–60 known taxa...

 as the dominant tree species. In the forest, common passerine

Passerine

A passerine is a bird of the order Passeriformes, which includes more than half of all bird species. Sometimes known as perching birds or, less accurately, as songbirds, the passerines form one of the most diverse terrestrial vertebrate orders: with over 5,000 identified species, it has roughly...

 birds dominate, along with buzzard

Buzzard

A buzzard is one of several large birds, but there are a number of meanings as detailed below.-Old World:In the Old World Buzzard can mean:* One of several medium-sized, wide-ranging raptors with a robust body and broad wings....

s, goshawk

Goshawk

The Northern Goshawk , Accipiter gentilis, is a medium-large bird of prey in the family Accipitridae, which also includes other diurnal raptors, such as eagles, buzzards and harriers....

s, sparrowhawk

Sparrowhawk

The Eurasian Sparrowhawk is a small bird of prey in the family Accipitridae. Adult male Eurasian Sparrowhawks have bluish grey upperparts and orange-barred underparts; females and juveniles are brown above with brown barring below...

s, long-eared owl

Long-eared Owl

The Long-eared Owl - Asio otus is a species of owl which breeds in Europe, Asia, and North America. This species is a part of the larger grouping of owls known as typical owls, family Strigidae, which contains most species of owl...

s, tawny owl

Tawny Owl

The Tawny Owl or Brown Owl is a stocky, medium-sized owl commonly found in woodlands across much of Eurasia. Its underparts are pale with dark streaks, and the upperparts are either brown or grey. Several of the eleven recognised subspecies have both variants...

s, black woodpecker

Black Woodpecker

The Black Woodpecker, Dryocopus martius, is a large woodpecker, 45–50 cm long with a 64–84 cm wingspan. Body weight is approximately 300-400 grams on average. It is easily the largest woodpecker in its range...

s, green woodpecker

Green Woodpecker

The European Green Woodpecker is a member of the woodpecker family Picidae. There are four subspecies and it occurs in most parts of Europe and in western Asia...

s and raven

Raven

Raven is the common name given to several larger-bodied members of the genus Corvus—but in Europe and North America the Common Raven is normally implied...

s. In winter months, whooper swan

Whooper Swan

The Whooper Swan , Cygnus cygnus, is a large Northern Hemisphere swan. It is the Eurasian counterpart of the North American Trumpeter Swan. An old name for the Whooper Swan is Elk; it is so called in Francis Willughby and John Ray's Ornithology of 1676.-Description:The Whooper Swan is similar in...

s and merganser ducks can be seen around the lake.

Madum Lake and the surrounding forest are owned by, respectively, Lindenborg Gods and Willestrup Estate. There is public access, and it is possible to walk around the lake on a marked route. Public fishing and boating on the lake is prohibited. At the lake's eastern shore is a large visitor parking space, from which extends a marked route to and around the Long Marsh - a large, well-preserved bog

Bog

A bog, quagmire or mire is a wetland that accumulates acidic peat, a deposit of dead plant material—often mosses or, in Arctic climates, lichens....

 in the forest to the east.

Contamination

Madum Lake has been declared a "Lobelia-lake", after the plant Lobelia

Lobelia

Lobelia is a genus of flowering plant comprising 360–400 species, with a subcosmopolitan distribution primarily in tropical to warm temperate regions of the world, a few species extending into cooler temperate regions...

, placing very special demands on water quality. However, there is evidence that in recent years the lake has been suffering from outside pollution. Both airborne nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

 and the more direct influence of hundreds of bathers in summer are obvious culprits. A clear sign of this contamination is seen in late summer in the form of algal blooms, and the reed

Reed

- Musical instruments :* Single-reed instrument, a woodwind instrument that uses only one reed to produce sound* Double reed instrument, a woodwind instrument that uses two reeds to produce sound...

-covered headlands have widened in recent years.