Water bodies

There are several lakes, ponds and springs as well as streams in the area of ​​Hollola municipality. The largest lake is Lake Vesijärvi, most of which is located in Hollola and not in Lahti.

The territory of Hollola municipality is divided into three main catchment areas according to the division of SYKE: Kokemäenjoki (35), Kymijoki (14) and Porvoonjoki (18) watersheds.

The largest lake in the Kymijoki watershed is Vesijärvi. Other lakes in this watershed are e.g. Tiilijärve (Little Tiilijärvi, Keski-Tiilijärvi and Iso Tiilijärvi), Kutajärvi, Soltinjärvi and Arkiomaanjärvi. Numerous small streams flow into Vesijärvi, the largest ones being for example Haritunjoki and Hammonjoki.

There are fewer lakes in the Porvoonjoki catchment area, the most significant are Työtjärvi and Hahmajärvi. Stream waters of the Porvoonjoki catchment area in the Hollola area include e.g. Vähäjoki, Koivusillajoki, Äväntjoki, and Hahmajoki. Porvoonjoki's original endangered trout population occurs only in the headwaters of the Hollola area.

In the catchment area of ​​Kokemäenjoki are located e.g. Sairakkalanjärvi, Valkjärvi and half of Pääjärvi located in Hollola's Hämeenkoski. The most significant stream is the Teuronjoki, which descends from Pääjärvi and continues its journey to Kärkölä. The above-mentioned belong to the eastern part of the catchment area of ​​Lake Mommilanjärvi and its unloading route. The western part, on the other hand, includes Kärpänjoki or Laihajoki and Pätilänjoki.