The administration of centrally fixed limit values may well be easier than emission standards set by reference to quality objectives, firstly when granting authorizations and, secondly, when monitoring to ensure compliance. When authorizing a discharge to water using the limit value approach the presumption will be that the emission standard will equal the limit value – unless there is an obvious reason for it to be more stringent – and so the authority is spared the difficulty of calculating the emission standard by first defining a quality objective (if none already exists) and then taking into account the existing quality of the river, volume of flow, and the number, quantity and quality of other discharges. Indeed, one of the arguments against variable emission standards is that quality objectives do not provide a complete guide for allocating the total acceptable pollutant load between dischargers. When a river crosses a frontier between authorities – which may be within a Member State or may be a national frontier – the administrative advantages of uniform emission standards become greater since the tricky problem of allocating the permitted pollutant load is eliminated. When monitoring to ensure compliance it may also be easier simply to sample the actual discharge to ensure that the emission standard has not been exceeded, than to sample the environment and then try to determine which of a number of discharges was responsible for any breach.