Figure 1: Sample locations used for this study . We discuss clumped isotope data from 135 samples collected from 96 sites in modern lakes, rivers, and springs. Blue circles indicate location of samples with new data from the Eagle-Tripati lab (n = 25; 159 measurements), orange triangles indicate data measured in the Eagle-Tripati lab that has been published and was recalculated onto the I-CDES reference frame for this study (n = 30), green diamonds indicate data from other labs that were recalculated onto the I-CDES reference frame as part of this study (n = 29), pink hexagons denotes sites where samples were analyzed twice, with one set of measurements being recalculated and the other taken directly from published data (n = 12), yellow stars represent data directly taken from other publications (n = 3).