A feasibility study is to be carried out to support the above-ground and underground water supply in the catchment area of the Straussee lake. The feasibility study is intended to examine whether it is possible, under ecological and economic conditions, to return seawater from Lake Kriensee, which is blended with swamp water from the water holding of the Rüdersdorf open-cast limestone mine, into the tributaries of the Straussee lake.

A feasibility study is to be carried out to support the above-ground and underground water supply in the catchment area of the Straussee lake. The feasibility study is intended to examine whether it is possible, under ecological and economic conditions, to return seawater from Lake Kriensee, which is blended with swamp water from the water holding of the Rüdersdorf open-cast limestone mine, into the tributaries of the Straussee lake.

In addition to the re-establishment of constant inflows into the Straussee, an outflow via Annafließ, Herrensee, Beckerfließ towards Stienitzsee is also to be made possible after reaching the normal level in Straussee. As a result, an ecologically stable state should be restored to these wetlands as well.

For the envisaged measure, it is also to be examined and evaluated to what extent the discharge of “blended” swamp water into the Klostersee/ Roten Hofgraben, with runoff into the Straussee as water body subject to WRRL reporting, does not lead to a deterioration in the condition. At the same time, the impact of the then 10-15% lower discharge of water into the Rüdersdorf Mühlenfließ must also be assessed. However, the discharge of mine water into the Rüdersdorf Mühlenfließ/Kalksee will be completed with the completion of the calcareous mine mine in Rüdersdorf (no later than 2062). Proposals should therefore be developed for the further introduction of water after limescale degradation has ended.

The processing of the feasibility study is divided into two phases.

The first phase includes issues relating to the economic efficiency and permissibility of the water transfer from Lake Krien to Lake Straussee.

In the second phase, questions regarding the water balance are answered and the influence on the ecological and chemical status of the affected water bodies is assessed.

The subject of this call for tenders is the services for phase 1. The allocation of services for the further investigations in phase 2 is dependent on the positive assessment of the financial viability and the principle of approvability of the external water support in phase 1.