<p>Hydrological monitoring of river-stage variability remains challenging on gauge-scarce river reaches, particularly under increasing drought and flood pressure in Central Europe. This study develops and tests a multi-mission satellite-altimetry workflow for detecting potential river-stage regime shifts in Polish rivers using nine virtual stations derived from Jason-2, Jason-3, and Sentinel-6 observations. The stations were located on hydrologically controlled reaches to enable validation, while the proposed workflow is intended to be transferable to poorly gauged and ungauged rivers. First, altimetry-derived water levels were validated against IMGW HD simulations at the virtual station locations, with nearby gauge observations providing complementary hydrological context. Next, the Standardized River Stage Index (SRSI) was calculated from the altimetry-based series at 1-, 3-, 6-, and 12-month aggregation scales to characterise multi-temporal water surplus and deficit conditions. To assess long-term changes in selected characteristics of the river-stage regime, annual integrals of SRSI were computed for total conditions and separately for values above and below zero. These metrics were then analysed using the Mann-Kendall test, Sen’s slope, Kendall’s tau, and Şen’s Innovative Trend Analysis and its extended variants (D-ITA and T-ITA).The validated virtual stations reproduced seasonal river-stage variability sufficiently well to support index-based assessment of hydrological conditions. Across the analysed stations, the results indicate a station-dependent tendency towards more negative cumulative river-stage anomalies, accompanied in several cases by a declining contribution of positive anomalies to the hydrological year balance. The proposed workflow provides a consistent framework for identifying potential river-stage regime shifts from satellite altimetry and can complement existing hydrometric and modelling systems, particularly on river reaches with limited in situ observations.</p>