The City of Dortmund (approx. 580,000 inhabitants as of 2010) has initiated and is responsible for the urban development of the Lake PHOENIX project. The city council's department responsible for urban planning and building developed the related urban master planning framework based on the visionary design of the architect, Norbert Kelzenberg. The urban development project was then realised by the development company "PHOENIX See Entwicklungsgesellschaft mbH” (a fully owned subsidiary of the local council services company "Dortmunder Stadtwerke AG") based on an agency contract. The new Emscher waterway is built and maintained in the context of the renaturing activities by “Emschergenossenschaft”, the water management association responsible for the River Emscher. It has purchased related areas and, on behalf of the City of Dortmund, will also assume responsibility for the water management of the Lake.

This complex urban restructuring project was launched in 2004 by dismantling the steelworks. When converting the site for the new Lake, approx. 2.8 million m3 of excavated land were used for landscape buildings and for terracing the edges of the slopes. Attractive residential areas were thus created on the southern and northern sides of the Lake. On the western lakeside, the existing district centre of Hörde is enlarged by a city port and a mixed functional urban area.

The Lake (area approx. 600,000m³) is primarily fed by groundwater and unpolluted rainwater from the new building sites. According to planning law, it has been planned as a dam. It has an additional water retention capacity of about 240,000m³ and in the future will serve as a flood retention space for the uncovered and restored River Emscher. In order to cope with extreme water flow events, a weir and a spillway crest were installed. A controllable drain was installed at the deepest point of the Lake to empty the Lake and clean the bed of the Lake, if necessary.

The River Emscher flows through an embanked riverbed without direct link to the Lake. In this way, the various ecosystems are separated from running and standing waters, sedimentation is prevented and the Lake is not strained by the water of the River Emscher, which might be rich in nutrients. Together with the renatured Emscher, the Lake forms a water landscape of 33 hectares, which, as a linking area, is an important element of the Emscher landscape park.

The costs for the project, costs for the purchase of land excluded, are about 168 million euros. The creation of the Lake and a lakeside area of 50m were financed from the funding programme “Ökologieprogramm Emscher-Lippe (ÖPEL)”. The “Emschergenossenschaft” water management association paid the costs for the Lake, which would have been caused by building the retention area, and the costs for building the new waterway of the Emscher The urban development measures were funded by the urban renewal programme of the Federal State of North Rhine-Westphalia.

In 2012, the River Emscher flows above ground again. Lake PHOENIX has been flooded and, according to monitoring results, has good water quality. It is surrounded by a 3.2km long food and cycle path and opened for leisure activities. Public infrastructure such as playgrounds, paths, green spaces and squares have been created. In the centre of Hörde, first new office buildings are being used. Numerous building plots for residential purposes have been sold, several residential buildings are being constructed, the first residential buildings are occupied.