The proper management of water resources is currently an important issue, not only in Poland, but also worldwide. Water resource management involves various activities including monitoring, modelling, assessment and designing the condition and extent of waters sources. The efficient management of water resources is essential, especially in rural areas where it ensures greater stability and efficiency of production in all sectors of the economy and leads to the well-being of the ecosystem.The performed analyses have demonstrated that the time of origin of the cadastral data defining the course of water boundaries has a significant effect on their quality. Having analysed the factors (timeliness, completeness, redundancy) used to assess the quality of cadastral data, their clear trend of changes in time was noticed. Thus, it is possible to specify the estimated degree of quality of cadastral data defining the course of watercourse boundaries only based on the information about the method, time and area of data origin in the context of the former partition sector.This research paper presents an original method of assessing the quality of spatial data that is used to determine the course of the shoreline of natural watercourses with unregulated channels flowing through agricultural land.The research has also demonstrated that in order to increase the efficiency of work, the smallest number of principal factors should be selected for the final analysis. Limiting the analyses to a smaller number of factors does not affect the final result, yet it definitely reduces the amount of work.