The Alte Donau is Vienna’s most popular lake for leisure activities.  The quality of the water in this 1.6 km² lake is excellent, its biodiversity high and its ecological vitality intact.

The Alte Donau, an oxbow lake formerly part of the Danube, is Vienna’s most popular lake for leisure activities. The quality of the water in this 1.6 km² lake is excellent, its biodiversity high and its ecological vitality intact. In order to keep it this way, the municipal department for water management (MA45) responsible for Vienna’s lakes and waterways began a wide-ranging EU project in July 2013. Around EUR 3.6 million – half of which is funded by the EU – has been made available, on the one hand to landscape the Alte Donau to bring it closer to nature and on the other to ensure that this green belt recreation area will still be there for future generations to enjoy.

New natural river banks

Around five and a half kilometres, one-third of the length of the Alte Donau banks, are to be landscaped to provide improved ecological habitats and to have a more natural appearance. New planting schemes and reed zones are to be established on sections of the banks, reeds renewed and tree trunks put in place as shelter for fish.

“ArbeiterInnenstrand” – new sunbathing lawn

A new, freely accessible sunbathing lawn with access to the Alte Donau has been in place since May 2015 on the upper Alte Donau. With an area of 23,000 m², the “ArbeiterInnenstrand” (Workers’ Beach) is the city’s largest area of open space returned to the public domain for decades. Many old trees and the reed bed were retained and more than 60 new trees were planted.

Getting people on board

Informing and involving the people who use the Alte Donau is an important aspect of the project. This includes questionnaires for neighbouring residents and workshops for children and adolescents. On June 5/6, 2015 a “Biodiversity Day” was held on the banks of the Kaiserwasser lake together with the Vienna’s municipal department for environmental protection (MA22). Guided walks around the Alte Donau, led by experts, are held several times a year. The new “Wiener Wasserweg” app provides interesting information on historical, cultural, natural and conservation themes at 21 virtual stations.

New signposting system for Alte Donau

It is now easy for people to find their way along the 13 kilometre trail around the Alte Donau thanks to the signposting system installed in the summer of 2015 by MA45, the municipal department for water management. A total of 20 signposts, most of them right by the water’s edge, indicate the way to go.

New soil filter since 2016

Spring 2016 sees the start of a construction project to provide a biological soil filter in the water park – the hydro-technical engineering heart of the LIFE project. This filter consists of a layer of stones covered with biofilm, which filters the water drawn from the New Danube (Neue Donau) to the Old Danube (Alte Donau) and removes nutrients from the water in the process.

As part of the LIFE+ project, plants such as the mare’s tail will be encouraged in the Alte Donau. The benefits are clear: these low-growing aquatic plants fulfil the same ecological purposes as the higher-growing ones but require less mowing.

Selection of activities to be completed from 2014 – 2017

• Further increase of the biodiversity, e.g. through planting and nurturing low-growing macrophytes (underwater plants that are of huge importance to the water quality)
• Continuation of the environmentally friendly and cost-effective cultivation of macrophytes, in connection with optimum protection of the fish stock
• Renaturation of further sections of the banks and the creation of new protection zones in bankside areas for the fish stock and other aquatic life, such as amphibians, dragonflies, aquatic and marsh plants
• Installation of a biological soil filter in the water park to maintain and improve the water quality of the Alte Donau (to be commissioned in July 2016)
• New signposting system for Alte Donau
• “ArbeiterInnenstrand” – new sunbathing lawn

Life+ Alte Donau project data

• Project title: Integrated Lake Management of the Urban Lake Alte Donau/Integratives Gewässermanagement des urbanen Stillgewässers Alte Donau
• Term: July 2013 to June 2017
• Budget: EUR 3.6 million, 50% funded by the EU
• Implementation: City of Vienna, Municipal Department for Water Management (MA45)

Contact

Mathilde Urban

MA 45 – Municipal Department for Water Management

E-Mail: mathilde.urban@wien.gv.at

Website: www.gewaesser.wien.at or www.life-altedonau.wien.at