The study area of Loutraki is located at the southeast part of Corinthian Gulf in Northeast Peloponnese. The maximum elevation is 1368 m a.s.l. and the climate is temperate with a mean annual temperature of 18.2 degrees Celsius. According to 2011 Census data, the permanent population of Loutraki town is 11,564 residents.

Loutraki study area and sampling sites in red square.

The aquifer of Loutraki according to WFD National Water Management Plans belongs to the porous groundwater body EL0600010 which is a protected area of drinking water and is characterized by a good qualitative and quantitative status. The aquifer develops in the Quaternary alluvial deposits of a trench filled with weathered ophiolite material. The host material of the saturated and unsaturated zones consists mainly of conglomerate, gravel and sand with local lenses of clay and silt. The porous aquifer is located in the lowlands of the basin which is developed in Quaternary and Neogene formations while karstic and ophiolitic aquifers are located at the north-eastern part of the basin.

Loutraki drainage basin lacks any heavy industrial activity and the main pressures posed to the groundwater body of Loutraki are diffused such as nitrification due to small scale agriculture at the southwest part of the drainage basin. Sea water intrusion due to over pumping is also identified along the coastal zone. Groundwater abstractions are mainly for drinking water supply (domestic use) and secondary for irrigation and industrial purposes (water-bottling plants).

The water demand of Loutraki is covered in supply by the alluvial unconfined aquifer located at the southern part of the basin. However, during the summer water demand increases as Loutraki is a popular tourist resort (population increases approximately by 50 %)and this causes additional pressure on the aquifer.

The present case study area is of particular interest as the lack of heavy industrial activity and intensive permanent agriculture makes it a natural analogue for the investigation of geogenic enrichment of groundwater with Cr(VI). Even though, the occurrence of Cr(VI) in the aquifer of Loutraki has been an issue of concern for both local population and local water management authorities as groundwater is the main source of drinking water.