Vesijärvi

Vesijärvi is a lake in southern Finland, located primarily in the city of Lahti in the Päijänne Tavastia region, with parts extending into neighboring municipalities. It is part of the Kymijoki drainage basin, and its waters flow through the Kymijoki river system toward the Gulf of Finland. The lake lies in a glaciated landscape associated with the Salpausselkä region and features a shoreline of bays, peninsulas, and forested shores.

Ecology and environment: Vesijärvi hosts species typical of boreal lakes, including perch, pike, and roach, with aquatic vegetation along the shore. In the 20th century the lake suffered from eutrophication caused by agricultural runoff and urban discharges, which reduced water clarity and increased algal blooms. Since then, nutrient-reduction efforts, improved wastewater treatment, and restoration programs have contributed to gradual improvements in water quality and habitat.

Human use and economy: The lake is a central recreational resource for Lahti, offering swimming, boating, and fishing along its accessible shoreline and parks. It also serves as a source of municipal water supply during certain periods and supports local tourism and outdoor activities. The Vesijärvi area is integral to the city’s waterfront identity and urban life, influencing promenades, neighborhoods, and cultural activities around the shore.

Name and history: The name Vesijärvi translates literally as “water lake” in Finnish. The lake has been part of the region’s history for centuries, shaping settlement, transport routes, and local industry along its shores.

See also: Lahti, Kymijoki, Salpausselkä.