Case study:Restoration of the River Paha-Paasonjoki
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- 1 Project overview
- 2 Image gallery
- 3 Catchment and subcatchment
- 4 Site
- 5 Project background
- 6 Reasons for river restoration
- 7 Measures
- 8 Monitoring
- 9 Additional documents and videos
- 10 Additional links and references
- 11 Supplementary Information
|Project web site|
|Themes||Fisheries, Habitat and biodiversity, Hydromorphology|
|Main contact forename||Jarmo|
|Main contact surname||Huhtala|
|Main contact user ID||User:Kasvio|
|Contact organisation||Centre for Economic Development, Transport and the Environment for Lapland|
|Contact organisation web site|
|Parent multi-site project|
| This is a parent project
encompassing the following
The River Paha-Paasonjoki is 2 020 meters long and it flows though forest areas from the Lake Paha-Paasonjärvi to the river Paasonjoki. The river bed is mainly sand and contains rocks and gravel. A big part of the river is marked as nature conservation area. The water quality in the river is good or very good.
The Centre for Economic Development, Transport and the Environment for Lapland restored three sections in the River. The restoration was made to improve the living conditions of the fish and other species. Rocks and gravel was placed to the river to make rapid areas more suitable for the trouts to reproduce. The aim of the retoration was to improve the living conditions of migratory fish and to make the river more nature-like and closer to its natural state. Trouts, grayling and macro invertebrates will benefit from the restoration and not only in the river but also in the nearby lakes. The rivers in the area are straightened for log floating since 1900 century. Also the natural state in the rivers are altered because of intense forestry and bog drainage.
The restoration plan was accepted 4.3.2011 and the work started immediately. The plan was restore six rivers in the area. The area is highly appreciated among the fly fishers and its very popular recreational area.
The restoration plan aimed to slow down the current and produce suitable nesting habitats for the trouts and shelter places for the juveniles. Also versatility to the river bed was improved by digging few wider areas. Gravel was brought approximately 40 m3 and placed to the river in several places bed to ensure the nesting habitats for the migratory fish. Before the restoration many stones were taken away from from the river and places a side of the river. All the stones that were piled up next to the river were used in the restoration work. Also wooden material was used to give more habiitats for invertebrates and versatility to the river flow.
The lenght of the first restored area is 260 meters and the width is 3,5 in average and the total area of the restoration is 1 000 m2. There are a lot of moss and algae growth because of eutrofication and nutirens coming from the forestry ares above the area. The nesting gravel is partly covered up with sand and sediment. The second was 640 meters long, width 4 meters and the area in total was 2 560 m2. The thirds section was 460 meters, width 4 meters and the area was 2 000 m2.
Monitoring surveys and results
Catchment and subcatchment
Cost for project phases
Reasons for river restoration
Hydromorphological quality elements
Biological quality elements
Physico-chemical quality elements
Additional documents and videos