A new concept for the determination of reference low flows of natural watercourses - the guaranteed minimum - has recently been introduced into the water management practice. Appreciating the significance underlying the definition of low flows in all segments of water management (municipal and industrial water supply, wastewater discharge, irrigation, navigation, hydropower, water protection, etc.), the author believes that all aspects of the problem must duly be considered, examined and identified. The doubts and issues raised by the guaranteed minimum concept in the domain of random-probabilistic phenomena, such as river discharge, are discussed in the paper.

The paper contains description of potential approaches to better defining of distribution curves parameters for low water levels on water courses that sporadically dry up, also including additional information on the length of dry period. Computed results are given for the example of minimum annual discharge on several rivers in the Velika Morava basin, Serbia (Serbia and Montenegro).