The mining region of Banská Štiavnica (Slovakia) has been inscribed into the UNESCO List of the World and Cultural Heritage in 1993. One of its special features is the system of artificial water reservoirs (locally referred to as “tajchy”) communicating via trenches built in early 18th century. The system was a water source, which drove the mining machines. Accumulation and transfer of sediments mainly depending on changes of land cover in the riparian zone leads to the loss of retention capacity and reduced life of reservoirs. Aim of this study is to analyse changes of the storage capacity/volume of the Veľká Kolpašská water reservoir that took place in the last is 123 years (1889–2012) and changes of land cover (LC) on the riparian zone in the course of the last 63 years (1949–2012). Volume and bottom relief changes were identified by comparison of bathymetric data drawn from the historical map of 1889 with the present data obtained in 2012 by bathymetric surveying. 3D models representing different situations were used for computation of the sediment volume. Results showed 57.801 m³ of sediments deposited in the course of 123 years that reduced the storage capacity of the reservoir by 7.23%. Changes of land cover in the riparian zone were detected via the analysis of aerial photographs (1949) and orthophotomaps from 2006, up-dated in the field for 2012. Analysis of changes show an increase of land cover categories which contribute to abrasion of banks, and the rate of sediment transfer to the reservoir ( by 11.030 m²) resulting in an increased silting potential.