November 30, 2021
The Porvoonjoki (Borgå å) is the main river in the Porvoonjoki watershed, the sources of which are located on the southern slopes of Salpausselä in Kärkölä, Hollola and Lahti. Upstream, the river is called Luhdanjoki. It flows through Orimattila, Pukkila, Askola and Porvoo to the Gulf of Finland. The farming landscape of the Porvoonjoki River with its ancient settlements, villages and manors together with the old Porvoo is a national landscape.
Porvoonjoki was originally a trade route for the people of Häme and its original name may have been Kukinjoki. The name would have its roots in the Friesian nomenclature of kugg, which would correspond to other similar trading places on the coast. 170 Stone Age dwellings from the oldest Stone Age in Finland have been found along the Porvoonjoki River. The agricultural landscape of the Porvoonjoki River with its ancient settlements, villages and manors, together with the old Porvoo, is one of Finland's 27 national landscapes.
The total length of the river is 143 kilometers and its catchment area is 1,271 km², of which only 1.4% are lakes. The lowest observed flow is a water cubic meter per second and the highest 200 m³ per second. The height difference between the beginning of the river in Lahti and the mouth at Porvoo is 68 meters, making an average fall of 0.7 meters. The largest tributary of the river is Palojoki and the largest lakes are Mallusjärvi, Isojärvi and Sahajärvi. The Porvoonjoki estuary is a Natura 2000 area.
Water quality, environmental standards
The Porvoonjoki is inherently cloudy because it contains clay. The river is particularly polluted by agriculture and urban waste water. Efforts have been made to limit agricultural emissions in protection zones. Strict environmental standards have been set for the river, but municipal wastewater is polluting the river. The bay uses the Porvoonjoki River as its main sewage system. The reproductive capacity of fish in particular is under threat due to drug residues. Recreational use of the river is difficult due to the large number of intestinal bacteria. The state of the river is gradually recovering.
The ecological status of the river is monitored by the Häme Environment Center up to Orimattila and from Askola by the Uusimaa Environment Center.
Phosphorus emissions flowing into the Porvoon River from Lahti have decreased by a third in 20 years. There are no official beaches in the river.
Recreational use of the river
The Porvoonjoki River has also had a lot of free-form association activities, such as the Eastern Uusimaa Water and Climate Protection Association. As part of the rehabilitation of its green areas, the city of Lahti has made a river bed suitable for paddlers between Ali-Juhakkala and Miekkiö. There is a canoeing route to the river with its landing places. There is no professional fishing along the river, and recreational fishing is limited. According to a 2005 survey, 46 families caught food fish. However, there is a desire to increase recreational fishing by building fish ladders and improving water quality. Rainbow salmon, grayling, pike, smelt, snout, snapper, perch, perch, brook trout, salmon and trout have been found in the river. Crabs died of crab plague in the 1950s. There are beaches in Pukkila and Kerkkoo maintained by common areas and village councils.
Hydropower has been utilized with the help of mills, sawmills and small power plants in many Porvoonjoki rapids.
Tönnönkoski, Orimattila, mill since 1589
Elsewhere on this topic
Pictures or other files about Porvoonjoki on Wikimedia CommonsPorvoonjoki more alive (PDF) 2019. Itä-Uusimaa and Porvoonjoki Water and Air Protection Association r.y.
Nature of the Lahti region.