Case study:Renaturation of Stržen's riverbed on intermittent Cerknica Lake

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Location: 45° 44' 52", 14° 22' 58"
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Project overview

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Status In progress
Project web site
Themes Environmental flows and water resources, Habitat and biodiversity, Hydromorphology, Social benefits
Country Slovenia
Main contact forename Irena
Main contact surname Likar
Main contact user ID
Contact organisation Notranjska Regional Park
Contact organisation web site
Partner organisations Institute of the Republic of Slovenia for Nature Conservation, HIDROTEHNIK Vodnogospodarsko podjetje d.d., The Fisheries Research Institute of Slovenia, DOPPS – BirdLife Slovenia
Parent multi-site project
This is a parent project
encompassing the following
View of the project area. Stržen's riverbed (straight channel and former meanders) is visible in the top half of the photo.

Project summary

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The main objective of the LIFE STRŽEN project is to improve the conservation status of the Habitats Directive priority habitat, Turloughs, by restoring the former Stržen riverbed. The watercourse will be prolonged by 1.5 km. This will have several positive effects, including an increased saturation of soil with water that will improve conditions for characteristic species of fish, invertebrates, birds and mammals. The project also aims at reducing the negative impact of visitors on the restored riverbed area and establishing quiet zones in the breeding habitat of the Eurasian bittern (Botaurus stellaris) in order to improve its breeding success. A further aim is to gain long-term support for its conservation actions among the general public, and a positive change of attitude among key stakeholders. Thus, the objectives are strongly linked to the EU Habitats and Birds directives, Biodiversity Strategy 2020, and Water Framework Directive.

Funding - EU Contribution: € 2,863,212.00

Monitoring surveys and results

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Lessons learnt

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Image gallery


Catchment and subcatchment


Name Watercourse Stržen – Cerknica Lake
WFD water body codes SI141VT2
WFD (national) typology
WFD water body name VTJ Cerkniško jezero (Cerknica Lake)
Pre-project morphology Artificially straight
Reference morphology
Desired post project morphology Sinuous - double meander
Heavily modified water body No
National/international site designation International - RAMSAR site
Local/regional site designations Regional Park – protected area
Protected species present Yes
Invasive species present No
Species of interest Great Bittern (Botaurus Stellaris), Common snipe (Gallinago gallinago), Spotted crake (Porzana porzana), Little Crake (Porzana parva), Marsh Harrier (Circus aeruginosus), Ruff (Philomachus pugnax) Red-necked grebe (Podiceps grisegena), Great white egret (Ardea alba), Purple heron (Ardea purpurea), Savi's warbler (Locustella luscinioides), Water rail (Rallus aquaticus), Great reed warbler (Acrocephalus arundinaceus), Northern shoveler (Anas clypeata), Ferruginous duck (Aythya nyroca), Wood Sandpiper (Tringa glareola), Italian crested newt (Triturus carnifex), Otter (Lutra lutra), Lesser Ramshorn Snail (Anisus vorticulus)…
Dominant hydrology
Dominant substrate
River corridor land use
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

Reach length directly affected (m) 1500
1,500 m
1.5 km
150,000 cm
Project started 2017/09/01
Works started
Works completed
Project completed 2022/08/31
Total cost category 1000 - 5000 k€
Total cost (k€) 3863
3,863 k€
3,863,000 €
Benefit to cost ratio
Funding sources European Union

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

Reasons for river restoration

Mitigation of a pressure Land drainage
Hydromorphology Quantity & dynamics of flow, Width & depth variation
Biology Fish, Invertebrates
Physico-chemical Temperature, Oxygen balance, Nutrient concentrations
Other reasons for the project


Structural measures
Bank/bed modifications Riverbed restoration
Floodplain / River corridor Establishing of quiet zones
Planform / Channel pattern Re-instatement of old course – double meander
Non-structural measures
Management interventions
Social measures (incl. engagement) Education of youth – admission-free field trips, ornithological camps, creative competitions; Active communication with key stakeholders – landowners, hunters, fishermen and tourism providers; Education of tourism providers.
Other Popularization of the project; information provision – project website, Information Bulletins, social media etc.


Hydromorphological quality elements

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Before measures After measures Qualitative Quantitative

Biological quality elements

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Physico-chemical quality elements

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Any other monitoring, e.g. social, economic

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Before measures After measures Qualitative Quantitative

Monitoring documents

Additional documents and videos

Additional links and references

Link Description proj id=6296#EI European Commission article about the project Official project website (English)

Supplementary Information

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