| Summary: | Lądek-Zdrój is situated within the tectonic unit of the Lądek-Śnieżnik metamorphic complex. Thermal water is captured by five springs and borehole L-2. These waters are characterized by TDS content in the range of 160–230 mg/L and predominance of HCO<sub>3</sub><sup>−</sup> (15–100% meq), SO<sub>4</sub><sup>2+</sup> (10–36% meq), and Na<sup>+</sup> (57–91% meq) ions. Increased concentrations of radon, hydrogen sulfide, and fluoride ions (7 mg/L–13 mg/L) determine the medicinal properties of these waters, classified as thermal waters of Na-HCO<sub>3</sub>-(SO<sub>4</sub>), F<sup>−</sup>, H<sub>2</sub>S, Rn type, with temperatures of 18 to 30 °C and 41 to 45 °C in springs and in the L-2 borehole, respectively. At the turn of 2018 and 2019, a new borehole LZT-1 was drilled in the area of Lądek-Zdrój. It captured thermal waters with a temperature of 37.4 °C at the outflow. The water temperature at the bottom of the heated borehole reached about 59 °C. The lithology of rocks found in the recharged areas implied that the Ca<sup>2+</sup> ions present in the studied waters originated from pyroxenes, amphiboles, calcite, calcium plagioclases, and fluorite. As for Na<sup>+</sup> and K<sup>+</sup> ions, they originate from sodium plagioclases, microcline, and orthoclase. The probable deposit temperature of waters from this borehole was estimated with the use of chemical geothermometers, as ranging from about 87 °C to 97 °C.
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