Helping Danube Fish To Pass The Iron Gate Dams

Helping Danube Fish To Pass The Iron Gate Dams
13 April 2021
Romania Serbia
CDM Smith recently won a new project to make the Iron Gate Dams passable for sturgeons and other native fishes. The Iron Gate Dams I & II on the border of Romania and Serbia are the most significant fish migration obstacles in the Danube River.

The impact of the dams and their hydropower plants has resulted in sharp declines of the formerly six native Danube sturgeon species in recent decades. Fish passage restoration is a high priority in the Danube River Basin Management Plan. Restoring fish migration at the Iron Gate dams will reopen about 1,000 km of the Danube River up to Slovakia and inac­ces­si­ble habitats and tributaries.


The European Commission’s Directorate-General for Environment hired CDM Smith to manage the project. Our respon­si­bil­i­ties include conducting a feasibility study, hydraulic modelling and fishway engineering. The feasibility study will include:

  • an alter­na­tives study to identify feasible options for upstream fish passage, fish protection and downstream passage restoration;
  • fish movement monitoring at the dams and in the reservoir using 2D and 3D telemetry; and
  • preliminary design of the preferred option(s) using BIM including 2D and 3D hydro-numerical modelling.
Building on a continuous development of fish passage know-how and track record in Germany, the Netherlands and Ireland in the past 5 years, this commission is a great win for us.
Marq Redeker, Business Development Manager in Germany
Iron Gates Danube ©Pecold -

CDM Smith provides lasting and integrated solutions in water, environment, transportation, energy and facilities to public and private clients worldwide. As an independent, employee-owned company, we work with team spirit and passion for the satisfaction of our clients and master the challenges of global change with intelligent solutions.

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With this project we will help to achieve 7.5% of the EU Biodiversity Strategy 2030 goal of restoring at least 25,000 km of rivers to a free-flowing state with a comparatively small set of focussed measures.