In 2014, the German Participatory Forum on Fish Protection and Downstream Migration was able to develop a common understanding of the size of a screen up to which functioning mechanical fish protection and descent systems, including the necessary cleaning technology, can be implemented. The objective of the research underlying this Fact Sheet 04 was to verify whether the statement of the German Participatory Forum on Fish Protection and Downstream Migration is confirmed in the actual operation of existing fish protection screens. Fact Sheet 04 "Technical functionality of large fish protection screens confirmed in practice" is available for download.

The core statements of Fact Sheet 04 are:

• The statement of the German Forum on Fish Protection & Downstream Migration that the current state of knowledge and technology allows functional fish protection screens at hydropower sites (up to approx. 50 m³/s discharge per screen) to be realised, is confirmed. They can be operated to protect fish larger than 10 cm and include the necessary cleaning technology.
• The use of screen cleaners with tooth- or brush-like elements can avoid problems with permanent congestions of fish protection screens with small bar spacing.
• Planning, design, and technical implementation of fish protection screens and screen cleaning are of major importance for the functionality of the hydropower site.