The area of ​​Carlas is a tectonic draft made during the first period of the Quaternary period and in which the first lake sediments were deposited. It was followed by filling with corrosion products carried by Pinios and other torrents from their catchment area. Lake Carla was known in antiquity (2,500 BC) under the name of Voieni. In the medieval years, the lake changed its name, and Carla became a member of the Viviers, while during the Ottoman domination it was mentioned as Carla Sou or Carla Giool. Also from the local population is also mentioned the name Valtos.

The fluctuations of the lake were intense during the prehistoric times, as a result of the various additions to it. In 1938-9 the first delimitation of the upper (48,50m) and the lower (47,30m) altitude of the level with the Law 5800/33 was carried out, and in the following years a new restriction of the lake's extent resulted from the flood defenses on the River Pinios. Its maximum depth of 5.5 meters before 1940 was reduced to 2 meters in 1950-5.

The fluctuations in the level, the floods in the area, the creation of more agricultural land and the reduction in catches and the need to reduce malaria epidemics contributed to the total drainage of the lake in 1962 despite the relevant studies that did not foresee this.

In 1959, a study was commissioned by the Ministry of Agriculture to exploit the Karla plain, with the construction of a reservoir of 64700 acres, a tunnel and low water trenches. The lake would be used for irrigation with irrigation channels and would be fed by Pineios waters. Instead, however, a tunnel was finally built for the complete evacuation of the lake, which began in January 1957 and was completed in October 1962. 

With the drainage of the lake, the terrible effects of the failure to complete the project, as envisaged by the construction of the 64700 acre reservoir, were apparent.

These impacts are both environmental and social:

Rapid fall of groundwater

Insertion of the sea front into the wider area of ​​the Carlas area Pollution and impact on the closed Pagasitic gulf and the appearance of phytoplankton Shallow cracks and destruction of buildings Impact on the fauna and flora of the area Destruction of boreholes and drying of sources including the High Fountain in Velestino Changes in the microclimate of the area The lack of watering of cities and settlements As the local formula said: "The construction of the tunnel was not a crime, it was a crime did not proceed to the restoration of the lake as initially planned ".

Even the fields resulting from the drainage of Carla, covering about 78,000 acres, did not yield the expected benefits as they flooded with the first downpour. Moreover, the salts that had accumulated in the soil from the former lake did not favor crops. Finally, rural land was never distributed, while landless farmers were renting land every year at a similar price. The limitation of exhaustive pumping of groundwater aquifers by water supply for irrigation

Improving water quality.

Protection of the Pagasetic Gulf due to the reservoir's anti-flood target and the improvement of overflowing water

Removing the seawater front that has entered the soil layer of Pagasitikos and has affected the aquifer 

Partial restoration of the microclimate of the area  

Source: http://www.fdkarlas.gr/History.aspx