LAKE LAGUNA SANTA ELENA, A FRESHWATER BODY, LOCATED IN MID-SOUTH OF CHILE, IS AN ENVIRONMENTAL ASSET USED AS A WATER RESOURCE BY THE AGRICULTURAL AND TOURISTIC SECTOR AND IS THE HABITAT FOR A WIDE VARIETY OF ENDEMIC AVIFAUNA. THE OBJECTIVE OF THIS STUDY WAS TO ASSIGN A MONETARY VALUE TO THIS LACUSTRINE BODY, USING THE METHODOLOGY OF AMUVAM (MULTICRITERIA ANALYSIS OF ENVIRONMENTAL ACTIVE VALUES). THE INFORMATION WAS COLLECTED THROUGH THE APPLICATION OF SURVEYS TO A PANEL OF EXPERTS INVOLVED IN THE USE OF THE ENVIRONMENTAL RESOURCE. THE RESULT OBTAINED WITH THE AMUVAM METHOD CORRESPONDS TO THE US $ 17,780,686, A FIGURE THAT REPRESENTS AN ESTIMATED VALUE OF THE TEV (TOTAL ECONOMIC VALUE) OF THE ENVIRONMENTAL ASSET. THIS STUDY, A PIONEER IN THE REGION, WILL SUPPORT DECISION MAKING, ALLOWING AN ADEQUATE MANAGEMENT OF THIS CRITICAL WATER RESOURCE.