The name Zuiderzee dates from after this event, as the water had before been a freshwaterlake that was only directly connected to the North Sea by the former river Vlie. The St. Lucia's flood removed the last of a series of natural sandy and boulder clay barriers, after which the new, now salty Zuiderzee came into existence and grew rapidly, since the peatlands behind the former barriers were now mostly unprotected against erosion from the sea. The coming into existence of the Zuiderzee was the undoing of the powerful medieval trading city ofStavoren on the right bank of the now disappearing river Vlie, and the making of first the IJssel Hanse-cities of Kampen, Zwolle, Deventer, Zutphen, and Doesburg, and later the anti-Hanseatic city of Amsterdam, which began its rise from nothing almost immediately after the St. Lucia's flood.
Much land was permanently flooded in what is now the Waddenzee and IJsselmeer. It especially affected the north and northwestern part of the Netherlands, particularly the current provinces of Noord-Holland and Friesland. The island of Griend in the current Waddenzee saw serious destruction, with only ten houses left standing. After the flood, Harlingen, about 25 kilometres southeast of Griend and formerly landlocked, came into existence as the new seaport of Friesland, a role it kept for seven centuries. The only part of the current northwestern Netherlands, apart from the western Dunes area and the Frisian Islands that escaped annihilation was West-Friesland, since this area was already protected by a ringdike that mostly held and where not, could be repaired after the floods receded. Shortly after the St. Lucia Day disaster, the West-Frisia, now separated from the rest of Friesland by a strait of around 15 kilometres at its narrowest, was annexed by the county of Holland, expanding this county northwards. The flood also brought the Friso-Hollandic Wars, which had lasted around 200 years, to an end. Shortly after this annexation, the West-Frisian cities of Hoorn and Enkhuizen began a rise to prominence that would last until the 17th century.
In Germany (mostly East Frisia)
The Chronicles speak of 50,000 killed and total destruction. Many villages disappeared forever. In the current district of East-Frisia alone thirty villages disappeared in the North Sea. Also a first stage of the Dollart came into existence. Because of the large loss of land and the relative insecurity of living in the now far more unprotected peatlands, since natural barriers had been removed by the flood, many survivors gave up their ways of living in the fertile peatlands and moved to the Geest.
In England
Although not known by the name of St. Lucia, the same storm also had devastating effects on the other side of the North Sea in England. It killed hundreds of people in England, e.g. in the village of Hickling, Norfolk, where 180 died and the water rose a foot above the high altar in the Priory Church. The storm is one of two in 1287 sometimes referred to as a "Great Storm". The other was the South England flood of February 1287. Together with a surge in January 1286, they seem to have prompted the decline of one of England's then leading ports, Dunwich in Suffolk.
