Two thousand years ago
Pomponius Mela, a
Roman geographer, mentioned a complex of lakes at the current location of the IJsselmeer. He called it
Lacus Flevo. Over the centuries, the lake banks crumbled away due to flooding and wave action, and the lake, now called the
Almere, grew considerably. During the 12th and 13th centuries, storm surges and
rising sea levels flooded large areas of land between the lake and the North Sea, turning the lake into a bay of the North Sea, called the
Zuiderzee. The Zuiderzee continued to be a threat to the Dutch, especially when northwesterly storms funnel North Sea waters towards the English Channel, creating very high tides along the Dutch coast. During the 17th century, Zuiderzee dykes collapsed several times, and plans were drawn up to eliminate the threat by draining the bay. Later drainage plans focused on creating fertile farmland, but they never progressed beyond the planning stage. It was only after the
flood of 1916 that the legislature approved the
Zuiderzee Works, a major hydraulic engineering project that involved building dykes, draining parts of the Zuiderzee, and constructing the
Afsluitdijk to keep tides and high water out. Construction began in 1927 and in 1932 the
Zuiderzee was closed off by the Afsluitdijk, a dyke connecting Friesland and North Holland on either side of the Zuiderzee. The Zuiderzee was no longer a sea inlet and was renamed IJsselmeer (
Lake IJssel) after the
IJssel river that flows into it, which is also the namesake of the province of
Overijssel. The continuing flow of fresh river water soon flushed out the salt water. Part of the IJsselmeer was later closed off to form the
Markermeer. From 1929 till 1967, over half the IJsselmeer was drained, creating of
polders:
Wieringermeerpolder,
Noordoostpolder, East and South
Flevoland. In 1975, a dyke was built between
Enkhuizen and
Lelystad as the northern boundary of the
Markerwaard, a planned but never realized polder in the IJsselmeer. This dyke, the
Houtribdijk or
Markerwaarddijk, split the IJsselmeer into two parts. The former southern part of the IJsselmeer is now the
hydrologically separate
Markermeer. The proposed "polderisation" of the Markerwaard was abandoned after many of the Dutch population did not want the loss of the traditional seaside (now lakeside) environment and vistas. In 1986 three
polders in the IJsselmeer constituted the new province of
Flevoland, the twelfth province of the Netherlands. The water of the IJsselmeer is now almost completely fresh, the saline having long since been purged. This altered environment has had an impact on the fish and plant
ecosystems. The change has been beneficial for Dutch boats, many of which are steel, as the freshwater significantly reduces rusting of the hulls, and there is far less build-up of marine growth (such as
algae and
barnacles below the
barges' waterlines). This has the knock-on benefit that barges and yachts in the IJsselmeer need far less
antifouling, a coating which is inevitably somewhat toxic to wildlife. == Current use ==