Siirt Billoris (Sağlarca) Spa

In Türkiye’s Southeastern Anatolia Region, known for its rich natural resources and cultural heritage, Siirt stands out as a district notable also for its geothermal potential. One of the most prominent examples of this potential is the Biloris Thermal Springs, located within the boundaries of the Eruh district. Known locally as “Sağlarca Thermal Springs,” this thermal site is situated on the banks of the Botan River, within a natural cave. Enriched with minerals, shaped by its geological structure and recognized for its health benefits, Biloris Thermal Springs is a site of scientific and touristic significance.

Biloris Thermal Springs is located 15 to 17 kilometers from the center of Siirt province, along the Siirt-Eruh highway, within the boundaries of Sağlarca Village under Eruh district. The springs lie directly beside the Botan River, inside a natural cave that has been expanded and adapted for therapeutic use. Access to the springs from Siirt is provided by vehicles traveling toward Eruh; Eruh town center is approximately 17 kilometers away. In addition to the main spring feeding the bathing pool, a second thermal source is located nearby, whose waters flow directly into the Botan River. This geographical setting renders the springs both accessible and surrounded by natural beauty.

The area where Biloris Thermal Springs are located has a complex geological history and is covered by formations from various periods. The oldest unit visible in the region is the Upper Cretaceous–Lower Paleocene Germav Formation, composed of grayish limestone, marl, sandstone, siltstone and milky limestone. Overlying this is the Paleocene–Lower Eocene Gercüş Formation, consisting of reddish marl, sandstone and conglomerate with localized limestone bands. Above it lies the Eocene Midyat Formation, whose lower levels contain marly limestone. Above the Midyat limestones is the Upper Miocene Şelmo Formation, composed of alternating layers of sandstone, conglomerate, siltstone and marl. At the top, Quaternary units are present: well to moderately consolidated polygenetic conglomeratic old alluvium, unconsolidated gravel, sand and pebbles, as well as travertine deposits left by the hot spring waters in the vicinity. The total thickness of this stratigraphic sequence reaches 170 meters.

Geothermal activity in the region is linked to tectonic movements. NW-SE trending anticlines, synclines and faults facilitate the upward movement of water to the surface. Young basaltic outcrops indicate that the geothermal gradient exceeds normal levels in certain areas. The spring waters emerge along these fault lines and originate from five distinct sources:

• Main Spring: Temperature 34.5°C, discharge 90 L/s.
• Second Source: Temperature 34.5°C, discharge 10 L/s.
• Ilıca Source: Temperature 33.9°C, discharge unmeasured.
• Cempir Ilısu Source: Temperature 30.6°C, discharge 0.01 L/s.
• Lif Ilısu Source: Temperature 33.1°C, discharge 10 L/s.

The combined discharge of these sources ranges between 172 and 173 L/s, with temperatures varying between 30 and 35°C.

The chemical composition of the spring water includes chloride, sulfate, bicarbonate, sodium, hydrogen sulfur and calcium minerals. The pH value is 6.4, indicating a slightly acidic character. Water temperature ranges between 33 and 36°C, making it suitable for bathing due to its proximity to human body temperature.

The therapeutic waters of Biloris Thermal Springs can provide supportive effects when used in bath therapy for various health conditions. Based on scientific literature research and local observations, the benefits of the spring water are well documented. It is used in bath therapy to alleviate pain and improve mobility in the chronic phases of inflammatory rheumatic diseases such as rheumatoid arthritis and ankylosing spondylitis like, as well as non-inflammatory joint disorders such as osteoarthritis and chronic belt pain. It is also employed to support the mobilization process in patients experiencing prolonged immobility following orthopedic surgeries or nervous system operations. In selected neurological conditions such as cerebral palsy, the soothing and restorative properties of the water contribute positively to rehabilitation. Furthermore, due to its mineral content, the water has been observed to offer supportive effects in certain skin conditions and gynecological disorders.^【1】 

Biloris Thermal Springs possess significant potential for health tourism due to their geographical location and natural surroundings. However, the current infrastructure is inadequate; there are no accommodation units, hygienic bathing pools or comprehensive medical services. Additionally, the mixing of Botan River waters with the spring sources may negatively affect the water quality.

Biloris (Sağlarca) Thermal Springs is one of Türkiye’s important thermal areas due to its geothermal resources. Despite its potential in health and tourism, this potential has not been fully realized due to infrastructure deficiencies and insufficient promotion. With increased scientific research and investment in infrastructure, the springs could become a significant asset for both the local population and health tourism.