Field demonstration of the combined use of thermally-degrading and cation-exchanging tracers to predict thermal drawdown in a geothermal reservoir

•Nonreactive, thermally-degrading, and cation-exchanging tracers were deployed.•The thermally-degrading tracer placed constraints on magnitude of thermal drawdown.•The cation-exchanging tracer placed constraints on timing of thermal drawdown.•Uncertainties associated with the thermal drawdown predictions are discussed.•Repeated use of thermally-degrading tracers could reduce predictive uncertainty.