Jeziorko Czerniakowskie: Warsaw's Largest Natural Lake and Its Future
The essentials: Jeziorko Czerniakowskie is the largest natural water body within Warsaw and a remnant of an old Vistula oxbow, protected as a nature reserve. The City of Warsaw reports that its water level has been falling for years and, in July 2026, commissioned in-depth expert analyses of ways to feed the reserve with extra water. In summer, a guarded bathing beach operates on the lake's southern end at Jeziorna 4.
Photo: Emptywords, Wikimedia Commons (CC BY-SA 4.0). the elongated oxbow lake of Jeziorko Czerniakowskie, seen from above in 2021.
A piece of the old Vistula
Jeziorko Czerniakowskie is the largest natural water body within Warsaw's boundaries and a leftover of the Vistula's former riverbed, the City of Warsaw says. Surrounded by a growing city, it forms one of the capital's most valuable natural enclaves and enjoys legal protection as a nature reserve.
Why the water is falling
Per the city, the lake is fed mainly by rainfall and surface runoff, and its condition also depends on the Vistula's hydrology. With no permanent inflow, the reservoir is gradually shallowing and rush vegetation is spreading - a trend made worse by years of drought, which in 2026 covered much of the country including the central region.
What the city is doing
In July 2026 the city announced it would commission in-depth expert analyses of the lake's future, including additional sources that could feed the reserve; each option must be assessed for feasibility, environmental impact and water availability, and any solution needs approval from the Regional Director for Environmental Protection. Earlier steps include a dedicated protection team and a rainwater-management concept for roughly 750 hectares of the Siekierkowski Arc on both sides of Trasa Siekierkowska, which foresees retention reservoirs and a partial feed of the lake from stormwater.
Swimming in summer
At the lake's southern end, at Jeziorna 4, the Mokotow sports centre runs a seasonal bathing beach. Per the operator, it offers a beach with a recreation area, a marked paddling zone for the youngest, and an outdoor gym; trained lifeguards watch over bathers and the water is tested by the sanitary inspection.
FAQ
Can you swim in Jeziorko Czerniakowskie?
Yes, in season, at the guarded bathing beach at Jeziorna 4 on the lake's southern end. Per the Mokotow sports centre, lifeguards are on duty and the water is tested by the sanitary inspection.
Why is Jeziorko Czerniakowskie protected?
It is the largest natural water body within Warsaw and a remnant of an old Vistula oxbow, and it holds legal protection as a nature reserve, per the City of Warsaw.
Is Jeziorko Czerniakowskie drying up?
The city reports a gradual fall in water level for years - the lake is fed mainly by rainfall and surface runoff. In July 2026 Warsaw commissioned expert analyses of possible new water sources for the reserve.
Sources
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