FRESHWATER ECOSYSTEMS SUPPORT SOCIETY THROUGH THE PROVISION OF GOODS AND SERVICES SUCH AS POTABLE DRINKING WATER, FISHERIES, POLLUTION ASSIMILATION, AND RECREATION. AQUATIC INVASIVE SPECIES (AIS) LIKE ZEBRA AND QUAGGA MUSSELS, COLLECTIVELY KNOW AS DREISSENIDS, ARE KNOWN TO SIGNIFICANTLY ALTER THE WAY IN WHICH FRESHWATER ECOSYSTEMS FUNCTION, NEGATIVELY EFFECTING THE FLOW OF ECOSYSTEM SERVICES THAT ARE IMPORTANT TO SOCIETY. THE PROLIFERATION OF DREISSENID MUSSELS ALSO CAUSES SIGNIFICANT ADVERSE ECONOMIC IMPACTS TO INDUSTRY, HOUSEHOLDS, AND GOVERNMENT. IN FALL 2017, DREISSENID MUSSELS WERE DETECTED IN MONTANA IN TWO LOCATIONS EAST OF THE CONTINENTAL DIVIDE. NO DETECTIONS HAVE BEEN REPORTED WEST OF THE DIVIDE IN THE FLATHEAD BASIN, WHICH FORMS THE HEADWATERS OF THE COLUMBIA RIVER, THE LAST MAJOR RIVER BASIN IN THE CONTINENTAL U.S. THAT IS MUSSEL FREE.PREVENTING AIS INTRODUCTION IS A PRIORITY FOR PROTECTING AQUATIC ECOSYSTEM SERVICES. HOWEVER, THE ECONOMIC CONSEQUENCES OF AIS DISRUPTIONS TO ECOSYSTEM SERVICES ARE POORLY DOCUMENTED, RESULTING IN INCOMPLETE COST ESTIMATES FOR AIS-RELATED DAMAGES AND, BY EXTENSION, INADEQUATE PUBLIC POLICY DECISIONS. NON-ANGLO AMERICAN VALUE SYSTEMS ARE ALSO ABSENT FROM PUBLIC POLICY. INCLUDING INDIGENOUS PEOPLES' NONMARKET VALUES IS ESSENTIAL IN PRODUCING A COMPREHENSIVE ACCOUNTING OF THE DISTRIBUTIONAL CONSEQUENCES OF AIS-RELATED MANAGEMENT DECISIONS ACROSS AFFECTED PARTIES.IN CO-DEVELOPMENT WITH THE CONFEDERATED SALISH AND KOOTENAI TRIBES (CSKT) OF THE FLATHEAD RESERVATION (MONTANA), WE PROPOSE TO DESIGN A CULTURALLY RELEVANT SURVEY INSTRUMENT AND DATA COLLECTION APPROACH APPROPRIATE TO A TRIBAL SETTING. BASED ON A SIMULATION MODEL OF THE FLATHEAD LAKE ECOSYSTEM, WE WILL DEVELOP A SET OF SCIENTIFICALLY PLAUSIBLE CHARACTERIZATIONS OF ECOSYSTEM SERVICES AFFECTED BY A DREISSENID MUSSEL INVASION. WE WILL PRETEST THE SALIENCE OF THESE HYPOTHETICAL OUTCOMES IN FOCUS GROUPS WITH MEMBERS OF THE CSKT. BY ENGAGING THE TRIBES FROM THE OUTSET, WE WILL ULTIMATELY GENERATE RESULTS THAT CAN YIELD MANAGEMENT APPLICATIONS THAT ARE CULTURALLY AND ECONOMICALLY RELEVANT TO THE TRIBE, THEIR CO-GOVERNMENTS, AND THEIR REGIONAL PARTNERS. IN CO-DEVELOPING A SURVEY INSTRUMENT FOR SUBSEQUENT ESTIMATION OF POTENTIAL COSTS TO CSKT OF ZEBRA/QUAGGA MUSSEL INVASION INTO FLATHEAD LAKE, WE SEEK TO INCREASE PRACTITIONERS' KNOWLEDGE OF HOW TO EFFECTIVELY CAPTURE THE TRIBAL PERSPECTIVE IN THE ARENA OF NONMARKET VALUATION THROUGH ASSESSING AND ADDRESSING INDIGENOUS WAYS OF KNOWING AND LAND GOVERNANCE.