Case study:Restoration of Porvoonjoki

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Location: 60° 25' 15.80" N, 25° 36' 39.67" E

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Project overview

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Status	Complete
Project web site
Themes
Country	Finland
Main contact forename	Vainio
Main contact surname	Sampo
Main contact user ID	User:Kasvio
Contact organisation	Itä-Uudenmaan ja porvoonjoen vesi- ja ilmansuojeluyhdistys
Contact organisation web site
Partner organisations
This is a parent project encompassing the following projects

The River Porvoonjoki

Project summary

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The river Porvoonjoki is the main river of the catchment area of the Porvoonjoki. The river runs from Lahti region to the City of Porvoo. It passes by many agricultural fields that are highly culturally significant to the area. The river is 143 km long anf the catchment area is 1 271 km2. The catchment area has only 1,4 % of lakes. The delta of the Porvoonjoki river is a Natura2000 area. The current has been more than 200 m3/s. The river has several rapid areas and 18 rapids have been restored to help the fish to migrate upwards the river. May restoration were done in the triburatory of the main river. Also fish (roe boxes and juveniles) have been introduced to the rapid areas. The fish populations have not risen as hoped due to the fishing and the obstacles to migrate.

Most of restoration actions are done by the local volunteers. In most of the restoration cases the rapids have received gravel, stones and also the paths for migratory fish have been opened. The stones will modify the current in the streams and give shelter areas for the fish. The gravel gives the salmonid fish places to reproduce and lay eggs.

The river is naturally very humid because of the loamy bottom. Agriculture and the sewage water from the domestic areas affects to the nutrient load to the river significantly. Buffer strips along the river have been established to prevent the nutrient load to the river. Fish studies have proven that the sewage waters that contain wastes from medicine affects the reproduction of the salmonid fish. The water quality In the river is getting better because of the better seage water management systems and water conservations actions in the agricultural areas.

The river is very popular as a recreational area. Many turists come to Porvoo for recreational fishing and to canoe in the River Porvoonjoki. There are many fish species in the River Porvoonjoki: salmo trutta, salmo salar, grayling, perch, pike, char.

There are several small hydropower stations along the River Porvoonjoki and its streams. Also there has been many old saws and mills but many of them have been opened up and now the fish can migrate upwards.

Monitoring surveys and results

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Lessons learnt

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Thanks to the local volunteers the restorations have been very succesfull and now the salmonid fish and many other fish species have better conditions to live and reproduce in the river. Still there are many barriers to the migratory fish and those issues need to be taking into consideratin in the future.

Image gallery

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The Koskela rapids before the restoration (photo:Vainio)

The Koskela rapids after the restoratrion (photo: Vainio)

The River Porvoonjoki in the City of Porvoo

Catchment and subcatchment Select a catchment/subcatchment Site Edit site Name WFD water body codes WFD (national) typology WFD water body name Pre-project morphology Straightened Reference morphology Desired post project morphology Actively meandering Heavily modified water body Yes National/international site designation Local/regional site designations Protected species present Yes Invasive species present Yes Species of interest Sea trout (Salmo trutta), Brown trout (Salmo trutta), arctic charr (Salvelinus alpinus) Dominant hydrology Ephemeral Dominant substrate Clay River corridor land use Intensive agriculture (arable) Average bankfull channel width category 5 - 10 m Average bankfull channel width (m) Average bankfull channel depth category Average bankfull channel depth (m) Mean discharge category Mean annual discharge (m3/s) Average channel gradient category Average channel gradient Average unit stream power (W/m2) Project background Edit project background Reach length directly affected (m) Project started Works started Works completed Project completed Total cost category Total cost (k€) Benefit to cost ratio Funding sources Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design Stakeholder engagement and communication Works and works supervision Post-project management and maintenance Monitoring Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Hydropower Hydromorphology Continuity for organisms, Width & depth variation Biology Fish: Abundance, Fish: Species composition Physico-chemical Nutrient concentrations Other reasons for the project Measures Edit Measures Structural measures Bank/bed modifications Barriers removal, Building fishway, Construction of gravel banks, Construction of meanders Floodplain / River corridor Removal of barriers Planform / Channel pattern Other Non-structural measures Management interventions Social measures (incl. engagement) Other Monitoring Hydromorphological quality elements Edit Hydromorphological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative [[]] Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative [[]] Physico-chemical quality elements Edit Physico-chemical quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative [[]] Any other monitoring, e.g. social, economic Edit Other responses Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Monitoring documents Upload monitoring documents Additional documents and videos Upload additional documents Additional links and references Edit links and references Link Description Supplementary Information Edit Supplementary Information