pH
2018–20197–7.2
Laboratory samples taken by the regional water authority near Svitiaz village; a separate series, not a multi-year mean.
51.4980, 23.8450karst-glacial lake
Lake Svitiaz
Світязь
- 58.4 m
- Maximum depth
- ≈6.9 m
- Average depth
- ≈26.2 km²
- Surface area
- 180.8 million m³
- Water volume
Verified dataset
Key facts
Svitiaz is the largest and deepest natural lake in Ukraine, the heart of Shatsk National Nature Park and of the UNESCO “West Polesie” Biosphere Reserve. It is a karst basin holding water of rare clarity — up to 8 m on a sunny day — whose western hollow reaches 58.4 m. Researchers treat it as the benchmark lake against which the state of the whole lake district is read.
Status: Shatsk National Nature Park; UNESCO “West Polesie” Biosphere Reserve
- Area
- ≈26.2 km²
- Maximum depth
- 58.4 m
- Average depth
- ≈6.9 m
- Shoreline
- ≈30.2 km
Water chemistry
calcium bicarbonate, soft, fresh
- pH
- ≈7.9
- Total dissolved solids
- ≈198.8 mg/L
- Transparency
- ≈5.4 m
- Dissolved oxygen O₂
- 10.5 mg/dm³
- Trophic state
- mesotrophic (weakly mesotrophic)
Ionic composition, mg/dm³
HCO₃⁻122
Ca²⁺34
Na⁺+K⁺15
Cl⁻13
SO₄²⁻10
Mg²⁺4
Mean ionic composition for 2018 (mg/dm³): HCO₃⁻ and Ca²⁺ dominate; the water is calcium bicarbonate and moderately fresh.
Field and laboratory measurements
Year and method matter: these values are not constantAmmonium nitrogen
2018–20220.08–0.25 mg N/dm³
Five summer laboratory reports.
Nitrates
2018–20220–1.2 mg/dm³
One-off summer samples; a 0 in the report does not mean the substance is entirely absent.
Nitrites
2018–20220.006–0.05 mg/dm³
Phosphates
2018–20220.004–0.16 mg/dm³
BOD₅
2018–20221.61–3.17 mg O₂/dm³
Biochemical oxygen demand over five days.
Dissolved oxygen
2018–20225.96–10.95 mg O₂/dm³
Values are available for 2018, 2019, 2021 and 2022.
Total iron
2018–20220.018–0.39 mg/dm³
Total hardness
2018–20222.4–2.9 meq/dm³
Bicarbonates
2018–2022146–256.2 mg/dm³
Suspended solids
2018–20226–8 mg/dm³
Bathymetry
Lake-bed profile: west → east
The bed has two contrasting zones: a shallow, sandy east, mostly 4–6 m deep, and a deep western basin with karst depressions reaching 58.4 m, where sapropel, marl and calcareous material accumulate.
West → east, 7.8 km: move across the water
Hlyb 58.4 mTuchna Pit 32 mOstrivenska Rise 0.6 m
—
0 km · Buzhnia Bay3.9 km7.8 km · Hriada shore
Thermal stratification
+23°C+9°C
Epilimnion · 5–10 m
The warm, mixed surface layer, up to +23 °C.
Metalimnion · 2–5 m
The thermocline, dropping 1,5–4,5 °C/m.
Hypolimnion · +9 °C
The cold bottom layer, stable year round.
In summer the water separates into distinct layers: the warm surface layer heats to +23 °C, while below 15–17 m the bottom water stays close to +9 °C all year round.
In-depth features
Explore Svitiaz in greater depth
27.50 → 26.21 km²
How Svitiaz changed: 1933–2023
What the 1933–2021 cartographic comparison, the satellite record and the exceptional low water of 2019 actually show.
Open feature →34 named features
Named underwater features of Svitiaz
An interactive map of 34 local names for pits, rises, bays, shoals and shore zones in Lake Svitiaz, with an explanation of accuracy.
Open feature →Ichthyofauna
Fish of the lake
Commercial catch structure, 2010–2018
Native species
Introduced / acclimatised
Invasive species
Ecosystem
Flora and birds
Red Book flora
Rannoch-rush (Scheuchzeria palustris)English sundew (Drosera anglica)lesser butterfly-orchid (Platanthera bifolia)Loesel's twayblade (Liparis loeselii)small cranberry (Vaccinium microcarpum)
Birds
white-tailed eaglemute swanmallardgreat cormorantwader
Feature
The island
7 ha
Area
800 m
Length
Almost at the centre of the lake lies an island of about 7 ha, stretched 800 m and covered with relict woodland — poplars, limes and sycamores. Today it is a strictly protected zone holding cormorant colonies. Legend ties the island to a sunken castle and to the “Island of Lovers”.
What to know
Lake in detail
- The largest and deepest natural lake in Ukraine, and the benchmark water body of the Shatsk lake district, whose area changed little between 1933 and 2021.
- The only lake in the system with a modern bathymetric map and a vertical thermal profile: in summer it stratifies directly, with an epilimnion of 5–10 m and a temperature drop of 1.5–4.5 °C per metre.
- In the deeper parts of the basin sapropel deposits reach about 2.5 m, while the bottom of the shallows is largely sandy.
- Across three multi-year series between 1971 and 2018, mineralisation ranged from 195 to 212 mg/dm³ with no sharp directional trend.
- A canal cut after the flood of 1887 links it to Lake Luky; it belongs to the connected system Svitiaz — Luky — Peremut — Ostrivianske — Pulemetske.
- In the commercial catches of 2010–2018, eel (43.5%) and roach (42.9%) dominated; in Svitiaz and Pulemetske 16 species were found to make up more than 90% of the fish biomass.
History
Chronology
- 1019
The area is first mentioned in the Primary Chronicle — the battle between Yaroslav the Wise and Sviatopolk near the lake complex.
- 1444
First documentary record of the settlement, the village of Svitiaz.
- 1531
First mention of the church of Saints Peter and Paul; a parish of the Liuboml deanery in the Chełm land.
- 1564
Lustration of the Liuboml starostwo: nine homesteads, with 35 people granted the privilege of free fishing in the lake.
- 1796
Cadastre: the village numbers 101 households and 508 inhabitants; together with the affiliated villages, 643 parishioners.
- 1846
The masonry church of Saints Peter and Paul, which survives to this day, is consecrated.
- 1899
The first thorough limnological study, by P. A. Tutkovskyi (published 1901).
- 1931
Stanisław Lencewicz carried out an early systematic morphometric and bathymetric survey of the lake; his material became the historical baseline for present-day comparisons.
- 1937
Demographic peak: 313 households and 2,426 inhabitants in the village.
- 1975
The first comprehensive hydrochemical campaign on Svitiaz and the other large lakes of the Shatsk group.
- 1983
Shatsk National Nature Park is established.
- 1985
Park staff begin a continuous record of water levels in Svitiaz.
- 2014
A modern bathymetric study is published, with an echo-sounding survey, an isobath map and analysis of the bottom sediments.
- 2018–2022
The regional water-resources laboratory in Volyn Oblast ran a series of summer water analyses near the village of Svitiaz: nutrients, oxygen regime, hardness, major ions and metals.
- 2019
The lowest level in half a century is recorded; the water surface shrank by roughly 8%.
- 2022
A comprehensive review of the hydrography, hydrochemistry and sapropel composition of the 28 Shatsk lakes is published.
Folklore
Legends of the lake
Below is the complete corpus of nine tales that Pavlo Tutkovskyi recorded from local peasants while studying Svitiaz and published in 1901. The language has been modernised while the plots and significant details have been retained. These are works of folklore, not historical or scientific evidence.
01
All 9 legends of Svitiaz →How Svitiaz and its island came to be
A folk tale about an old traveller, herdsmen, water bursting from beneath a stone and the trees on the island of Svitiaz.
Read in full →07A bell for the church or the tavern
A Svitiaz tale about a great bell caught in a fishing seine and the dispute that sent it back into the water.
Read in full →09The catfish without end or measure
An old Svitiaz fisherman’s tall tale about a gigantic catfish that seized a man by the leg.
Read in full →Important distinction: Adam Mickiewicz’s ballads “Świteź” and “Świtezianka” concern the Belarusian Lake Svityaz near Navahrudak, not Svitiaz in Shatsk. Tutkovskyi noted only that in 1899 he had heard a similar sunken-city story in Volyn but had not recorded it.
State and recreation
The lake today
Recreation
Summer water: ≈23 °C
Beaches: Central beach (Svitiaz village), Hriada locality, Private-sector beaches
Recreational fishing in designated zones under catch permits; commercial fishing is banned, and spring and summer spawning closures apply. Since 2023 border-zone restrictions cover part of the park.
Water level
163.3 m a.s.l.
Current
162.94 m
Low 2019
The level swings seasonally — highest in spring, lowest in autumn — against a long-term downward trend. In October 2019 it reached an absolute half-century low of 162.94 m, and the water surface shrank by roughly 8%.
Ecological pressures
Khotislav Quarry
Chalk extraction to a depth of 40 m in Belarus could create a cone of depression and draw off groundwater.
≈25 km from the lake; designed depth 40 m
Recreational Overload
Load limits exceeded 20–25 fold at peak season; chlorides and sulphates rising from municipal wastewater.
150,000–170,000 visitors per season
Melioration Legacy
Marsh drainage in the 1960s–80s depleted the artesian horizons, bringing siltation and eutrophication of the littoral, and shoaling.
1–2 cm of siltation a year in the shallows
Rank in the group
#1by area · of 30
#1by depth · of 27
#5by mineralisation · of 10
Each measure counts only the lakes that report it.
Hydrology
Hydrological connections
The Shatsk lakes are not isolated bodies of water but a connected network. Canals cut between the late nineteenth and the mid twentieth century, along with natural channels, redistribute water between the lakes and the rivers.
Outflow
Lake Luky
An 1887 canal with a regulating sluice; Svitiaz discharges into Luky, whose level lies 1.5 m lower.
Inflow
Lake Lynovets
Lynovets feeds Svitiaz by gravity — its own level is 10 cm higher.
Geography and access
Places nearby
All places →village
Svityaz village
Svityaz is a resort village on the southern and south-eastern shore of the lake of the same name. It is the principal hub for beach access and visitor accommodation around Lake Svitiaz.
Open profile →resort area
Hriada
Hriada is a named locality and established recreation area on the north-eastern shore of Lake Svitiaz. It is not a separate village, so the guide classifies it as a tourism territory.
Open profile →village
Pulmo
Pulmo is a village between Lakes Svitiaz and Pulemetske and an important gateway to the western part of the Shatsk lake district. Routes from here reach both large lakes and several smaller waters.
Open profile →settlement
Shatsk
Shatsk is the administrative centre and main gateway to the Shatsk lake district. The settlement lies between Lakes Liutsymyr and Chorne Velyke and concentrates the community’s everyday services.
Open profile →Language note
Editorial scope
This English profile carries the full narrative, chronology and local traditions. Source titles stay in their original language, and the Ukrainian page remains the reference version.
Read the Ukrainian profile →Sources
Source titles are retained in their original language.
- Озеро Свитязь и народные предания о нем [Lake Svitiaz and folk tales about it] (1901)
- Діяльність П. А. Тутковського на Волині: каталог матеріалів П. А. Тутковського у фондах Волинського краєзнавчого музею [Pavlo Tutkovskyi’s work in Volyn: catalogue of Tutkovskyi materials in the Volyn Regional Museum]
- Культура та побут населення Шацького приозер’я в народній топонімічній прозі [Culture and everyday life of the Shatsk lake district in folk toponymic prose] (2019)
- о. Світязь [Lake Svitiaz]
- Світязь науковий [Svitiaz in science]
- Якість води в озері Світязь за вмістом хімічних елементів під впливом антропогенного навантаження [Water quality in Lake Svitiaz by chemical element content under anthropogenic pressure] (2024)
- Світязь [Svitiaz]
- Основні аспекти морфометрії та гідрохімії Шацьких озер [Key aspects of the morphometry and hydrochemistry of the Shatsk lakes] (2020)
- Hydrography, hydrochemistry and composition of sapropel of Shatsk Lakes (2022)
- Dynamics of Hydromorphological Parameters of Lakes of Shatsk National Nature Park (1933–2021) (2022)
- Assessment of the dynamics of the surface area of the Shatsk Lakes over a long-term period based on remote sensing data in connection with fluctuations in their level (1985–2023) (2025)
- Shallowing of the Svityaz Lake in the context of regional climate change (2020)
- Батиметричні дослідження озера Світязь: минуле, сучасність та перспективи [Bathymetric studies of Lake Svitiaz: past, present and prospects] (2014)
- Сучасний стан іхтіофауни та рибопродуктивність озер Шацького НПП [The current state of the fish fauna and fish productivity of the lakes of Shatsk National Nature Park]
Photo: RbrechkoCC BY-SA 4.0cropped