This paper investigates whether the endogenous geothermal energy resources used for local tourism facilities are a factor of local development. We answer this research question by examining the local socioeconomic development dynamics in years 1995–2015 in the six selected Polish municipalities that established geothermal spas at different years. A model introduces the concept of switch variables, where a geothermal spa is the assumed switching factor in a municipality’s socioeconomic development. The statistical procedures are adopted from factor analysis and trend estimation methodologies. Our conclusions lead to a positive assessment of a geothermal water park’s contribution to a municipality’s socioeconomic development.