The Jadro Spring is a water source rising in the Dinaric Alps

Dinaric Alps

The Dinaric Alps or Dinarides form a mountain chain in Southern Europe, spanning areas of Slovenia, Croatia, Bosnia and Herzegovina, Serbia, Kosovo, Albania and Montenegro....

 in Croatia

Croatia

Croatia , officially the Republic of Croatia , is a unitary democratic parliamentary republic in Europe at the crossroads of the Mitteleuropa, the Balkans, and the Mediterranean. Its capital and largest city is Zagreb. The country is divided into 20 counties and the city of Zagreb. Croatia covers ...

. The spring was the original water supply

Water supply

Water supply is the provision of water by public utilities, commercial organisations, community endeavours or by individuals, usually via a system of pumps and pipes...

 for the ancient city comprised by Diocletian's Palace

Diocletian's Palace

Diocletian's Palace is a building in Split, Croatia, that was built by the Roman emperor Diocletian at the turn of the fourth century AD.Diocletian built the massive palace in preparation for his retirement on 1 May 305 AD. It lies in a bay on the south side of a short peninsula running out from...

 (now an area within the present day city of Split

Split (city)

Split is a Mediterranean city on the eastern shores of the Adriatic Sea, centered around the ancient Roman Palace of the Emperor Diocletian and its wide port bay. With a population of 178,192 citizens, and a metropolitan area numbering up to 467,899, Split is by far the largest Dalmatian city and...

). Contemporary studies indicate favourable water quality

Water quality

Water quality is the physical, chemical and biological characteristics of water. It is a measure of the condition of water relative to the requirements of one or more biotic species and or to any human need or purpose. It is most frequently used by reference to a set of standards against which...

 levels at the spring source. The Jadro Spring is the source of the Jadro River

Jadro River

The Jadro River is a watercourse in Dalmatia, Croatia that discharges to the Adriatic Sea. The upper reaches of the Jadro River as well as its source are protected as an ichthyological nature reserve, partly due to the presence of an endemic species of soft-mouthed trout...

. A rare species

Rare species

A rare species is a group of organisms that are very uncommon or scarce. This designation may be applied to either a plant or animal taxon, and may be distinct from the term "endangered" or "threatened species" but not "extinct"....

 found in the upper reach of the Jadro River

Jadro River

The Jadro River is a watercourse in Dalmatia, Croatia that discharges to the Adriatic Sea. The upper reaches of the Jadro River as well as its source are protected as an ichthyological nature reserve, partly due to the presence of an endemic species of soft-mouthed trout...

 is the soft-mouthed trout

Trout

Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...

, Salmothymus obtusirostris salonitana

Salmothymus obtusirostris salonitana

Salmo obtusirostris salonitana is an endemic trout subspecies found in the Jadro River in the vicinity of Solin , and in the nearby Žrnovnica River...

.