Case study:Rehabilitation of the river Segeråga

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Location: 66° 43' 0.13" N, 13° 16' 28.41" E

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Project overview

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Status	In progress
Project web site
Themes	Fisheries, Habitat and biodiversity, Land use management - agriculture, Monitoring, Water quality
Country	Norway
Main contact forename	Kjetil
Main contact surname	Hansen
Main contact user ID
Contact organisation	Municipality of Rødøy
Contact organisation web site	http://www.rodoy.kommune.no/
Partner organisations
Parent multi-site project
This is a parent project encompassing the following projects	No

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Project summary

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Project background

Segeråga is located in Rødøy and Meløy municipality in the northern part of Norway. The river has been exposed to significant man-made changes during the last 30 years. New cultivation problems in the upper part of the river, with drainage and ditching of large peatlands, have had a documentable and significant negative ecological consequence for the river. The river has had increased sludge of fine particulate inorganic material (sludge/fine sand). The fish stock have probably been significantly reduces because of this.

The primary goal for the project is to increase the stocks of anadromous salmonids in Segeråga compared to the period 2013-2019. A secondary goal is that the content of erosion and organic material in the water is reduced compared to the pre-situation, and that the river's quality as a habitat for fish and freshwater organisms is improved, especially through a reduction in the sludge of functional areas for trout and salmon.

Implementation

The project started with surveys in 2014, 2015 and 2016. Two reports describes the aquatic ecological status of segeråga, through benthic and juvenile fish surveys in the watercourse, supplemented with some water chemistry. Based on this knowledge from the surveys, as well as field inspections and problemmapping, a rehabilitationplan was made in 2017. The rehabilitationplan suggests rehabilitation measures to re-establish the river as a river with sea-migrating salmonids, with particular emphasis on recovering the sea trout stock. This project was also a pilot project for this type of smaller rivers with man-made changes and new cultivation problems. The rehabilitation started in 2017 includes measures as removing the inorganic material (sludge/fine sand), digging out ponds, gravel for spawning grounds, fish ladder, reduce runoff from agricultural land, habitat improvement, sediment ponds and reinforcement of riverbanks.

Summary/conclusion

The project successfully implemented all planned measures, with some locale adjustments in the field, such as the placement of spawning gravel. There has been no conflict with the landowners, and some have been involved in the measures. The project has been possible due to a committed municipality and funding from the state. The last measures were implemented in 2020. Therefore, the results of the measures are not yet available. It will be important to monitor the river in a few years, to see the result from the measures and evaluate the project.

Monitoring surveys and results

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Lessons learnt

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Image gallery

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Catchment and subcatchment Select a catchment/subcatchment Site Edit site Name Segeråga WFD water body codes 159-194-R WFD (national) typology RMM1221 WFD water body name Segeråga Pre-project morphology shallower, overgrown Reference morphology Desired post project morphology Run-glide, Ponded, Pool-riffle Heavily modified water body No National/international site designation Local/regional site designations Protected species present No Invasive species present No Species of interest Atlantic salmon (Salmo salar), Sea trout (Salmo trutta), arctic charr (Salvelinus alpinus) Dominant hydrology Perennial Snow-rain (SR) Dominant substrate Silt River corridor land use Intensive agriculture (arable), Coniferous woodland (semi natural) Average bankfull channel width category 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) 1000010,000 m <br />10 km <br />1,000,000 cm <br /> Project started Works started Works completed Project completed Total cost category 100 - 500 k€ Total cost (k€) 206206 k€ <br />206,000 € <br /> Benefit to cost ratio Funding sources Norwegian Environment Agency, County Governor og Nordland Cost for project phases Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname Investigation and design 10 - 50 k€ 3636 k€ <br />36,000 € <br /> Rødøy municipality Stakeholder engagement and communication Works and works supervision 100 - 500 k€ 170170 k€ <br />170,000 € <br /> Rødøy municipality Post-project management and maintenance Monitoring Reasons for river restoration Edit reasons for restoration Mitigation of a pressure Land drainage Hydromorphology Channel pattern/planform, Continuity of sediment transport, Flow velocities, Structure & condition of riparian/lake shore zones, Substrate conditions, Width & depth variation Biology Fish: Abundance, Fish: Age structure, Invertebrates: Diversity Physico-chemical Nutrient concentrations Other reasons for the project Bank erosion Measures Edit Measures Structural measures Bank/bed modifications Construction gravel bays, gravel for spawning grounds, Removal of sediment, Removal of fish barriers, Natural erosion embankments, er Floodplain / River corridor Removal of sediments Planform / Channel pattern Decrease sedimentation, Creation of pond Other Fish habitat restoration, Improving fish migration, sediment ponds Non-structural measures Management interventions Reducing bank side collapse (source of sediment) 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 Substrate conditions Yes No Yes No No Awaiting results Width & depth variation Yes No Yes No No Awaiting results Biological quality elements Edit biological quality elements Element When monitored Type of monitoring Control site used Result Before measures After measures Qualitative Quantitative Fish: Abundance Yes No No Yes No Awaiting results Fish: Age structure Yes No No Yes No Awaiting results Invertebrates: Diversity Yes No No Yes No Awaiting results Invertebrates: Abundance Yes No No Yes No Awaiting results 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 Nutrient concentrations Yes No No Yes No Awaiting results PH Yes No No Yes No Awaiting results 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 http://https://brage.nina.no/nina-xmlui/handle/11250/2446580 Plan for rehabilitation of the river http://https://brage.nina.no/nina-xmlui/handle/11250/2436896 Fish biological survey http://https://niva.brage.unit.no/niva-xmlui/handle/11250/2478427 Survey of physico-chemical quality elements and biology Supplementary Information Edit Supplementary Information