Humans have had a significant effect on the watercourses on Lolland and Fehmarn through straightening, deepening and eutrophication. On Lolland in particular, many watercourses are artificial, dug-out canals that end at a pumping station with an outlet to the sea. Over time, nature has made its contribution to these man-made waterways.  

Watercourses and lakes are important
Watercourses and lakes serve as habitats for animals and plants. They are also destinations for recreational outings. Watercourses also play an important role in leading rainfall away from the soil and thereby protecting our homes, agricultural lands, and roads against flooding.

Therefore, work is being done to investigate animal and plant life, water quality, water flow, and direction for all watercourses and lakes located in close proximity to the access installations. Later, their vulnerability to discharge from road run-off and other drainage water is evaluated.

Effects from the fixed link
If the fixed link is built as a bridge, the access ramps will be on embankments raised above the ground. If the decision is made to build a tunnel, these ramps will be in cuttings dug into the ground.

The bridge solution focuses on protecting watercourses and lakes from water that is led away from asphalted areas. Such water may contain contaminants that can be harmful to the marine environment.

If a tunnel is constructed, it may be a question of draining the ground water during both the construction and operational phases. Groundwater drainage may reduce the water level in watercourses and lakes, which increases the risk of drought during dry spells. A tunnel may also mean that the watercourse may have to be rerouted, because digging may need to be so deep that it will not be possible to lead the watercourse underneath without making it impossible for fish and other water-living animals to pass.

How watercourses and lakes are protected
The purpose of the EIA includes determining how to prevent harm to watercourses and lakes. If it

becomes clear that a necessary lowering of groundwater changes the water level in watercourses or lakes, the pumped groundwater will be led back to the lake or water course so that the water level can be maintained.

Drainage basins will be built for this purpose where water led away from roads and railways will reside for a period of time so any harmful elements can settle. Water from the drainage basin will then be released in limited quantities, and in the event of an accidental spill of particularly contaminated materials, the flow can be entirely shut off.

A stream threads its way along a dyke on Fehmarn's northern coast. (photo: Trüper Gondesen Partner)

Many of the watercourses on both Lolland and Fehmarn have been strictly regulated, and therefore almost ruler-straight. (photo: Jan Fischer Rasmussen)