Lake Ertso

Lake Ertso (ერწოს ტბა – Ertsos Tba) is recognized as the largest known karst lake in Georgia. It is situated in Java Municipality (within the disputed territory of Tskhinvali Region/South Ossetia, historically part of Shida Kartli), near the village of Ertso. Located at an elevation of approximately 1710 meters above sea level in the Kvirila river basin area, this permanent lake possesses a unique character derived from its karst origin. Its basin occupies four distinct karst sinkholes, giving its shoreline a complicated shape. Fed by permanent streams, rainfall, snowmelt, and underground karst waters, Lake Ertso supports fish life and is surrounded by forested mountains and meadows. Despite significant seasonal water level fluctuations and freezing over for nearly five months in winter, it maintains a considerable depth in parts. The lake holds conservation significance, being listed in the “Red Book of Georgia”.

Identification and Location:

• Name of the Lake: Lake Ertso (ერწოს ტბა – Ertsos Tba).
• Location:
  • Country/Region: Georgia, Java Municipality (Tskhinvali Region/South Ossetia – occupied/disputed territory), historically Shida Kartli region.
  • Specific Location: Near the village of Ertso, northwest side of the Ertso-Tsona depression area.
  • Nearest Major Landmark/Area: Village of Ertso, Kvirila river basin area.
  • Coordinates: Approximately 42.47∘N,43.75∘E.
  • Relationship to other bodies of water: Fed by three permanent streams and underground karst water systems. Although located in the Kvirila basin area, its direct outflow mechanism via karst channels might be complex.

Physical Characteristics:

• Surface Area: Approximately $0.31$ km2.
• Maximum Depth: Reaches up to $19$ meters.
• Average Depth: Approximately $2.1$ meters.
• Volume: Approximately 0.65 million cubic meters.
• Elevation: Approximately $1710$ meters above sea level.
• Shoreline Length: Has a complicated, irregular shoreline due to its formation within multiple sinkholes.
• Water Source(s): Receives water from three permanent rivers/streams, snowmelt, rainfall, and underground karst water sources.
• Outlet(s) (if any): Drainage occurs through the karst system, likely via underground channels connected to the sinkholes forming the lake basin.
• Water Type: Freshwater.
• Basin Geology: Karst lake. Its basin is formed by four interconnected karst sinkholes developed in the underlying soluble rock (likely limestone).

Ecological Information:

• Flora (Plant Life): Surrounded by mountain forests and meadows. Aquatic vegetation presence depends on depth and substrate within the different sinkhole basins.
• Fauna (Animal Life): The lake supports fish populations, including carp species. The surrounding terrestrial environment hosts fauna typical of the region’s mountain forests and meadows.
• Trophic Level: Specific trophic status information is limited, but likely ranges based on nutrient inputs from streams and internal processes.
• Water Clarity: Water is generally clear.
• Water Temperature: Surface water temperature reaches 23–25 °C in summer. The lake freezes over in winter.
• pH Levels: Specific information unavailable; likely influenced by karst geology.
• Dissolved Oxygen Levels: Specific information unavailable; sufficient to support fish populations.
• Unique Ecological Features: Largest known karst lake in Georgia. Habitat supporting fish populations at a relatively high altitude. Included in the “Red Book of Georgia” indicating conservation value.
• Conservation Status: Listed in the “Red Book of Georgia”. Its location within a disputed territory affects current conservation management possibilities.
• Invasive Species: No information available.

Human Interaction and Significance:

• Historical Significance: Located near the village of Ertso, part of a historically inhabited region. Karst lakes often hold local cultural significance.
• Current Uses: Can be reached via a dirt road and is used locally for picnics. Fishing occurs in the lake.
• Environmental Issues: Karst systems are inherently sensitive to pollution entering groundwater feeders. The lake’s ecosystem could be impacted by changes in water quality or quantity from its feeding streams. The political situation impacts environmental monitoring and management.
• Management and Conservation Efforts: Its listing in the Red Book highlights its recognized need for protection, but active management is hindered by the geopolitical situation.
• Local Communities: Provides a local recreational spot (picnics, potentially fishing) for residents of nearby areas when accessible.

Interesting or Unique Facts:

• Officially recognized as the largest karst lake in Georgia.
• The lake basin is uniquely formed by four distinct, water-filled karst sinkholes.
• Listed in the “Red Book of Georgia”, signifying its national conservation importance.
• Experiences significant water level fluctuations seasonally, highest in May-June and lowest in August-September.
• Freezes over for almost five months during the winter.