Some twenty years ago WIS-dredging has been developed in the Netherlands. By injecting water into the mud layer, the water content of the mud becomes higher, it becomes fluid mud and will start to flow. The advantages of this system are that there is no need of transporting the mud in a hopper, and no need for a pipeline. Also from an energetic point of view the solution is attractive. The system requires however a different way of payment. Most efficient is a maintenance contract with a dredging company in such a way that the company guarantees a given nautical depth for a fixed sum per year. For the port authority it makes budgeting much easier, because the maintenance dredging will become a fixed amount per year. The limitations are that WIS-dredging is only possible in case the material consists mainly of mud, the mud has to be quite clean, and the disposal should not be too far away from the dredging site.