The National Hydrological Plan (NHP), approved by Law 10/2001, of 5 July, laying down the basic elements for the coordination of the BHP, the solution for the possible alternatives offered by the latter, the forecast and the conditions of the transfers of water resources between territorial environments of different river Basin Hydrological Plans and the changed predicted in the planning of the use of the resource and which affect current uses of water supply for inhabited areas and irrigation.
It was later amended by R.D.Law 2/2004 of 18 June on the Reform of the National Hydrological Plan and Law 11/2005 of 22 June which amends Law 10/2001 of 5 July of the National Hydrological Plan.