In Germany, there are extensive legal and statutory provisions for water management. They includes the European directives (such as the Water Framework Directive), which, only became binding with the transposition into national German law.
The most important legal basis is undoubtedly the Water Resources Act. Then there are the 16 state water laws as well, having numerous sub-statutory regulations and administrative provisions. There are also other (specialized) laws such as; the Soil Protection Act, the Nature Conservation Act or the Act on of Environmental Impact Assessment all affecting water management in general and stormwater management in particular.