Return of wet dune slacks in the Meyendel dunes. Before 1874, the dune areas around the city of The Hague, the Netherlands contained many rare plant species. After that, the Hague started drawing too much of the ground water away for human use and the valleys dried out. Around 1950, the Dune Water Company created infiltration ponds in the dunes to provide drinking water for the city and surrounding parts, and the natural water level under the dunes rose again. But the infiltrated water came from the rivers and contained too many fertilizing compounds, causing bushes and grass to grow wild at a disadvantage to the rarer plant species.