The Leuvekolk, an extension of the Rotte River located north of Blaak in Rotterdam, has undergone a major transformation. The waterfront now features a sunbathing area, additional green spaces and a landing area for canoes.
A water inlet supplies fresh water to the Leuvekolk, while a fish passage enables fish to migrate between the Leuvekolk and the Nieuwe Maas River. Construction began in February 2019 and was completed in 2023.
The first phase involved establishing a freshwater inlet from the Nieuwe Maas. An existing, disused pipeline beneath Blaak and Plein 1940 was repaired for this purpose.
An additional freshwater inlet became necessary following the deepening of the Nieuwe Waterweg shipping channel, which allows salt water from the North Sea to penetrate further upstream. The additional inlet at the Leuvekolk is opened when the river carries fresh water from inland areas.
This helps ensure a sufficient supply of fresh water for agriculture, horticulture and the natural environment along the Rotte River, even during periods of drought.
CI-Engineers has been involved in the fish passage project since 6 September 2021. The passage enables fish to migrate between the Nieuwe Maas and the Rotte in both directions.
Migration between saltwater and freshwater environments is essential for species such as glass eels and sticklebacks. Providing an unobstructed migration route also contributes to maintaining healthy fish populations.
Within the Leuvekolk, fish encounter strong currents and fluctuating water levels, with differences exceeding one metre. The fish passage allows fish to overcome these differences in elevation while reducing the impact of strong currents.
The passage consists of a series of interconnected concrete basins, each positioned six centimetres higher or lower than the adjacent basin.
This stepped arrangement enables fish to gradually ascend or descend along the basin floor. Sheltered areas in the corners of each basin naturally guide fish towards the opening to the next basin. Dedicated resting basins allow fish to pause during their migration.
CI-Engineers was responsible for developing the concrete geometry drawings and reinforcement detailing for the fish passage.
Client: Municipality Rotterdam
Visualisation: BOOM Landscape
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