The outlines of Trieste Bay showed in quaternary, when the Adriatic sea basin and its existing coastline were formed. Isolated Koper Island (Insula Capritana) towered above the shallow bay, while Sermin Hill (Insula Risani) was located 3 km eastwards and appeared like an island due to its marshy surroundings and Rižana estuary.
Koper Bay was divided in two smaller bays: Škocjan (or Stanjon) Bay, eastwards of Koper Island, where Badaševica river was flowing into until the middle of the 1980s and smaller but deeper Polje Bay (Val di Campi) to the north of Rižana estuary. Both rivers deposited alluvial material to the bottom of the bay. With large quantities of gravel, sand and clay, deposited around the Sermin Hill, Rižana River created extended plateau and estuary, which narrowed the straits and formed the Škocjan Bay.
On the naturally protected Koper Island, the Romans established town called Aegida. It is presumed that they created simple saltpans in marshes and shallows around the island. In the turbulent late antiquity before migration of peoples, the town was called Capraria – goat’s island – or Caprae, where the Slovenian name Koper derives from.
The formation of Škocjanski zatok is connected with urbanistic development of the City of Koper and its surroundings. It started with construction of saltpans, when the pools for evaporation of water were formed. In the times of Venice Republic after 1279, saltworks around the bay expanded significantly. They were protected from high tides and river floods with embankments and regulated through a network of draining channels. Smaller Semedela Saltpans clinged to the Koper Island from the southern side, while near Rižana estuary and in Polje Bay larger Sermin Saltpans were formed. At the same time, some saltworks were established on eastern coast of Škocjan Bay.
After the decline of the Venice Republic, the saltpans have fallen into decay. Before 1911, the production of salt has been totally abandoned due to salt price decrease. In the next three decades, the saltpans were left uncared for and exposed to the influence of the weather conditions and high tides. Later on, the Italian authorities decided to drain the abandoned saltpans and regulate the surrounding rivers. In the period from 1932 to 1939, most of the water regulation works were implemented in the area. It started with works in Semedela area: sea embankments were built, as well as reservoirs, drainage and other channels, water pumps were mounted and Badaševica estuary regulated. At the same time, Semedela bonifika was created and that’s how Koper island became connected with the mainland. Eastwards from Semedela bonifika, a shallow Škocjan Bay was formed, which gradually became an important habitat for marine fauna and flora. In the beginning of the 1960s, the Port of Koper was started to being built in the immediate surroundings of the City of Koper, spreading towards Ankaran. The pier was built all along the Škocjan Bay, which became more and more closed, until it finally got lagoon character. The lagoon of today’s Škocjanski zatok remains the very last witness, proving that Koper originally used to be an island.
Pictorial presentation of Škocjanski zatok formation (Source: Manca Plazar – Restoration of Škocjanski zatok near Koper, 1995).