The Aksu Deposit is located in Eastern Prissykul, 15 km southeast of the town of Krakal, in the river mouth area of the Ak-Suu River — a right tributary of the Arashan River, at absolute elevations of about 1750 m. The first descriptions of the deposit were made in the mid-20th century by the famous geographer P. P. Semenov-Tyan-Shansky, although local residents were undoubtedly aware of it long before that.
Geologically, the thermal waters are associated with a system of fractures that extend almost meridionally, with a typical steep drop to the east in areas where thermal waters manifest, cutting through porphyritic granitoids of the Late Ordovician. Anomalously high-temperature waters are found in springs along the valley and have been extracted by three exploratory wells with depths of up to 208.5 m, one of which was drilled back in 1932 and continues to operate to this day, providing hot water for therapeutic baths.
In natural outcrops, the water temperature slightly reaches 40° C, while the discharge from the wells does not drop below 57° C, reaching 60° C in the most productive well (No. 2). In terms of macrocomponent composition, the water is sodium sulfate-chloride with an increased fluoride content (up to 13 mg/l) and a total mineralization of just under 0.4 g/l. Among the microcomponents, lithium, molybdenum, and boron are found in elevated amounts; due to its silicon acid content (up to 55 mg/l), it is classified as therapeutic siliceous water, the balneological effect of which is undoubtedly enhanced by the presence of up to 5 mg/l of dissolved hydrogen sulfide.
The reserves of siliceous thermal waters at the Aksu deposit exceed 1500 m3/day and more than adequately meet the resort's needs for therapeutic, heating, and household water. It should be emphasized that due to the high fluoride content, this water is completely unsuitable for regular drinking and domestic consumption.
