In the Netherlands, state-owned water company PWN and three water filtration companies are working to preserve the water supply of the country's dune lands, by introducing livestock to ensure the health of the ecosystem.
In 2007, bison and other large grazers were introduced into the Dutch dunelands, an area from which water is drawn to serve 4.4 million people (15-20% of national water supply). As Mongabay reports, "the grazers keep tree and shrub growth in check and allow the dune ecosystem, home to 50 percent of the country’s biodiversity, to reach optimal ecological health."
Since their introduction, the grazers have helped maintain the ecological health of the area, whilst preserving the water supply. Prior to this, there had be no bison in the Netherlands for thousands of years.
This has been a success for both the water companies and conservationists alike. The water collected requires less chemical filtration, as it is naturally filtered on the dried-out dune slacks, and a natural water reservoir has also formed in the area. The bison heard has also thrived, growing from just 3 to 22 since their introduction in 2007.
It is a good example of systems thinking in action: the livestock help the natural water cycle self-regulate, enabling the water companies not only to recude their chemical needs, but ensuring the longevity of supply.