The entire River Vantaa catchment (1680 km2) is covered by the Case Study. The River Vantaa runs 99 kilometers through heavily populated (1 million people) and agriculturally intensive areas. The mean rate of flow is about 17 m3/s and there are 150 small lakes in the region. River Vantaa (Fig. 1.1) is a subcatchment of the Kymijoki-Suomenlahti River Basin District (VHA2).
Substances
studied: PAH; PBDE
; Nonylphenol; DEHP
; TBT (TPhT)
The catchment area of the River Vantaa and the adjacent coastal areas. (Note that the geographical boundary of the system at the river estuary is bordered by the archipelago.)The estuary with two bays are located within the coastal boundaries of the study. These areas have considerable harbor activity and receive urban drainage as well.
The River Vantaa runs through 14 municipalities. It is used as a recipient of treated wastewater from three municipalities, four wastewater treatment plants and some small utilities. The amount of processed wastewater is about 2.5% of the annual mean flow. Industrial wastewaters are treated together with municipal wastewaters
The river is a secondary drinking water source for the City of Helsinki. It is used as the main water source during the repair of the Päijänne raw water tunnel. The river is also used for recreation and fishing, and additional flow from the Päijänne raw water tunnel has been led to the tributary, River Keravanjoki, in order to maintain adequate recreational value during the summertime.There is considerable variation both in the flow rate and rainfall between months. Most of the rainfall occurs in the autumn and there is generally a high spring outflow of melt water from the catchment area. These factors affect significantly the temporal dynamics and the interpretation of measured concentrations.
Stakeholders and decision makersBased on the environmental legislation polluters have to carry out statutory monitoring of recipient waters and wastewaters. The stakeholders have voluntarily collaborated in the protection of the river since the 1960s through the Water Protection Association of the River Vantaa and Helsinki region. The association is responsible for monitoring the functioning of the wastewater treatment plants and water quality in the river for the point source polluters. In addition, it aims at improving the recreational values of the river. However, this association is not a decision maker in the strict governmental sense of the WFD.
