Paliastomi Lake

Paliastomi Lake (პალიასტომის ტბა) is a significant coastal lake located in western Georgia, situated on the border of the Samegrelo-Zemo Svaneti and Guria regions, very close to the Black Sea coast and the city of Poti. It forms the heart of the Kolkheti National Park, an area recognized globally for its unique ecosystems, designated as both a UNESCO World Heritage Site (as part of the Colchic Rainforests and Wetlands) and a Ramsar wetland of international importance. Paliastomi is not a typical freshwater lake; it’s a relict lagoon, a remnant of an ancient sea bay, connected to the Black Sea via a channel. This connection results in brackish water, with salinity levels fluctuating depending on river inflow and sea conditions. Fed primarily by the Pichori and Kaparchina rivers, the lake is relatively large in surface area but quite shallow. Its low elevation (partly below sea level) and surrounding extensive wetlands create an exceptionally rich habitat, particularly renowned as a crucial stopover and wintering ground for vast numbers of migratory birds. It also supports a diverse fish fauna, important both ecologically and for local fisheries. Historically, the area is linked to the ancient Greek colony of Phasis, adding cultural significance to its natural wealth.

Identification and Location

• Name: Paliastomi Lake (პალიასტომის ტბა). Also sometimes spelled Palaeostomi.
• Location:
  • Country: Georgia
  • Region: Borders Samegrelo-Zemo Svaneti and Guria regions.
  • Municipality: Near Poti city, also bordering Khobi and Lanchkhuti municipalities.
  • Nearest Landmark: City of Poti, Black Sea coast, Kolkheti National Park visitor center.
  • Coordinates: Approximately 42°07′ N latitude, 41°45′ E longitude.
  • Relationship to other bodies of water: Directly connected to the Black Sea via a channel. Fed primarily by the Pichori and Kaparchina rivers. Part of the extensive Kolkheti wetland system.

Physical Characteristics

• Surface Area: Approximately 17.3 – 18.2 square kilometers (about 6.7 – 7 square miles).
• Maximum Depth: Shallow, typically around 3.2 meters (about 10.5 feet). Some sources mention up to 6m.
• Average Depth: Shallow, around 2.6 meters (about 8.5 feet).
• Volume: Relatively modest due to its shallowness (estimated around 52 million cubic meters).
• Elevation: Very low, close to sea level, with parts potentially slightly below mean sea level (e.g., -0.3 m).
• Shoreline Length: Extensive, characterized by marshes, peatlands, and wetland forests typical of the Colchis Lowland.
• Water Source(s): Primarily inflow from the Pichori and Kaparchina rivers, direct precipitation, and influx from the Black Sea through its connecting channel.
• Outlet(s): A channel connecting it directly to the Black Sea. (Historically, the connection was less direct; the current strait formed/widened significantly in the 1920s-1930s).
• Water Type: Brackish; salinity varies depending on river discharge and seawater intrusion. Became significantly more saline after the direct channel to the sea was established/widened.
• Basin Geology: Relict lagoon formed by coastal sedimentation processes on the Colchis Lowland.

Ecological Information

• Flora (Plant Life): Dominated by wetland vegetation including extensive reed beds (Phragmites), water lilies (Nymphaea), yellow floating-heart (Nymphoides peltata), and specific Colchic wetland plant communities (including relict species) in the surrounding marshes and peatlands. Also features wetland forests (alder, oak, wingnut) with characteristic Colchic undergrowth (ivy, rhododendron).
• Fauna (Animal Life): Exceptionally important for birds (around 194 species recorded in the park); a key site on the East Asian-East African migratory flyway. Hosts hundreds of thousands of wintering and migratory birds, including pelicans (Dalmatian and Great White), cormorants, herons, egrets, swans, geese, ducks (like Common Pochard), coots, waders (curlews), and potentially eagles (White-tailed Sea Eagle). Diverse fish fauna (around 88 species reported in the park’s aquatic systems) including both freshwater species (carp, pike-perch, catfish, pike, rudd) and euryhaline (brackish/marine tolerant) species like mullet, flounder, gobies, herring, sturgeon species, Black Sea Salmon. Important spawning and nursery area for fish. Supports amphibians (tree frog, pond frog, newts), reptiles (water snake, pond turtle, Aesculapian snake). Mammals like otter, golden jackal, wild boar, and roe deer inhabit surrounding wetlands.
• Trophic Level: Eutrophic, characterized by high nutrient levels and biological productivity.
• Water Clarity: Generally low due to shallow depth, sediment inflow from rivers, and high productivity.
• Water Temperature: Follows the mild coastal climate patterns; rarely, if ever, freezes completely. Summer average water temperature around 25°C, winter around 5°C.
• pH Levels & Dissolved Oxygen Levels: Variable; oxygen levels can be lower in bottom layers or dense vegetation.
• Unique Ecological Features: Unique Colchic wetland ecosystem. Brackish water habitat. Critical bird migration stopover/wintering site. Important fish nursery. Core zone of Kolkheti National Park (UNESCO World Heritage & Ramsar site). Contains relict flora.
• Conservation Status: Highest level of protection as part of Kolkheti National Park. Designated Ramsar site (#893). UNESCO World Heritage status (Colchic Rainforests and Wetlands). Several resident/migratory species are listed in Georgian or international Red Lists.
• Invasive Species: Potential presence of invasive aquatic plants or animals needs ongoing monitoring within the park management framework.

Human Interaction and Significance

• Historical Significance: Strongly associated with the location of the ancient Greek colony and city of Phasis (circa 6th century BC). Archaeological remains (dating back potentially to the 2nd century AD and earlier Bronze/Iron ages in the wider area), possibly related to Phasis, have been found submerged in or near the lake.
• Current Uses: Fishing (commercial and recreational, regulated within the National Park). Tourism (major component of Kolkheti National Park, featuring boat tours, birdwatching platforms/tours). Scientific research. Not used for drinking water, irrigation, or power.
• Environmental Issues: Potential threats include pollution from inflowing rivers (carrying agricultural runoff or waste from settlements), pollution from nearby Poti port and industrial activities, changes in salinity balance due to climate change or channel modifications, eutrophication, poaching/illegal fishing, and disturbance to wildlife from unregulated activities. Historical drainage of surrounding wetlands has also impacted the ecosystem.
• Management and Conservation Efforts: Managed by the Agency of Protected Areas under the strict regulations of Kolkheti National Park. International status (UNESCO, Ramsar) brings additional focus and standards for conservation. Fishing is regulated (specific species, seasons, gear restrictions apply).
• Local Communities: Important for local communities through employment in tourism (guiding, boating), regulated fishing activities, and cultural identity linked to the lake and Kolkheti region. Local legends exist about the lake’s formation (e.g., the flooding of the “Tribe of Pavlia”).

Interesting or Unique Facts

• A relict lagoon representing a former bay of the Black Sea.
• Contains brackish water due to its connection with the sea, which significantly increased after channel modifications in the 20th century.
• Lies at the heart of the Kolkheti wetlands, a UNESCO World Heritage site known for its relict ecosystems.
• One of the most important sites for migratory bird concentration (especially waterfowl) in the Caucasus region and along the flyway.
• Believed to hold submerged archaeological evidence potentially linked to the ancient city of Phasis.
• Its low elevation places parts of it slightly below mean sea level.
• It’s the third largest lake in Georgia by surface area (after Paravani and Kartsakhi).