IMPACT OF THE SEWAGE DISCHARGE FROM HOT SPRINGS TO WATER SOURCES

Hot springs have traditionally been a tourist attraction in many parts of the world, such as Japan, Canada, Taiwan among others. During the peak tourist season, it is usually discharged into streams without treatment, which can affect the quality of the receiving water, causing negative impacts to the aquatic ecosystems. Downstream ecological impacts of several major spa recreational sites in different parts of the world have been studied and it has been found that wastewater discharges of hot springs have ecological adverse effects.   However, the mineral composition in hot springs derived mainly from groundwater is greater than that of stream water. Studies carried out with models such as QUAL2k (or Q2K), the modernized version of the QUAL2E (or Q2E), simulate the effect of the discharge of hot springs on surface water sources. In the case of water quality at Nan Shin Creek in Taiwan, the model results show that bathing water from hot springs has a significant adverse impact on its water quality, during periods of minimum flow. A major factor though, which needs to be taken into account and duly evaluated is that, the hot spring wastewater is estimated to contribute up to 50% of effluents discharged into the receiving water, which may be the principal reason for the significant impact of the hot spring water in this case.   Despite the negative consequences of the impacts on ecosystems derived from hot springs wastewater, it is interesting to note that there are regulations for wastewater discharges – including backwash water from swimming pools – into rivers and sewers (Germany, Canada), but not specifically for hot springs discharge. This may be due to generally limited effluent amounts normally discharged into the receiving water and/or because the significance of hot spring water (mineral) composition itself is little compared to the anthropogenic contamination, deeming the source of the bathing water less important. The United States Environmental Protection Agency gives a special authorization to discharge under the national pollutant discharge elimination system in case of hot springs. However, it is necessary for the authorities to increase the control of the use of hot springs and the discharge of their untreated waters. Regarding Colombia, Resolution 631 of 2015 regulates the discharge of wastewater into rivers and sewers. However, it does not consider parameters for the discharge of hot springs.