Green Waters of the Markermeer, the Netherlands – June 11th, 200952.5N 5.2E
Sediments and algae color bodies of water near the Dutch coast various shades of brown and green. Particularly striking is the bright yellow-green Markermeer (bottom center), a 700 km² lake in the central Netherlands between North Holland, Flevoland and its larger sibling, the IJsselmeer.
A shallow lake at some 3 to 5 m in depth, it is named after the small former island, now peninsula, of Marken that lies within it. The southwest side of the lake is known as the IJmeer.
The Markermeer used to be part of the Zuiderzee, a saltwater inlet of the North Sea. This inlet was dammed off by the 32 km long Afsluitdijk (Closure Dike) in 1932, turning the Zuiderzee into the freshwater IJsselmeer.
The following years saw the reclamation of extensive tracts of land as large polders in a massive project known as the Zuiderzee Works. Part of the construction of the last polder was building the Houtribdijk, also called Markerwaarddijk, finished in 1976, which hydrologically splits the IJsselmeer in two, the southern section being the Markermeer.
The Markermeer was not originally intended to remain a lake; one of these polders, the Markerwaard, was to occupy the area of the current Markermeer. However, because of changing priorities and doubts about the financial feasibility, the Markerwaard was indefinitely postponed in the 1980s and the Markermeer has since begun to become a valuable ecological and recreational asset of its own.
The Markermeer is used as a freshwater reservoir and a buffer against floodwaters and droughts. In 2003 the Netherlands was hit by drought, and several minor dikes were endangered. Water from the Markermeer was used to keep the area surrounding Amsterdam wet, thereby keeping the dikes safe.