To investigate the hydrology of Utah Lake, we analyzed the hydrogen (δ2H) and oxygen (δ18O) stable isotope composition of water samples collected from the various components of its system. The average δ2H and δ18O values of the inlets are similar to the average values of groundwater, which in turn has a composition that is similar to winter precipitation. This suggests that snowmelt-fed groundwater is the main source of Utah Valley river waters. In addition, samples from the inlets plot close to the local meteoric water line, suggesting that no significant evaporation is occurring in these rivers. In contrast, the lake and its outlet have higher average δ-values than the inlets and plot along evaporation lines, suggesting the occurrence of significant evaporation. Isotope data also indicate that the lake is poorly mixed horizontally, but well mixed vertically. Calculations based on mass balance equations provide estimates for the percentage of input water lost by evaporation (~47%), for the residence time of water in the lake (~0.5 years), and for the volume of groundwater inflow (~700 million m3) during the period April to November. The short water residence time and the high percentage of total inflow coming from groundwater might suggest that the lake is more susceptible to groundwater pollution than to surface water pollution.

<div><i>Exhibiting America</i> explores the varied ways that the Smithsonian’s National Museum of American History – under different names over the years – conveyed the story of America to millions of annual visitors in its first 137 years. While NMAH's size and prominent location in the nation’s capital have usually meant its leaders aspired to grand visions, often the realities of exhibition development have tempered and reshaped its exhibitions in unexpected and provocative ways. <i>Exhibiting America</i> takes readers through five distinct eras, describing and analyzing the museum’s major exhibitions. To mark the start of a new era for the museum, Allison and Peterson offer reflections on trends and continuing challenges for the National Museum of American History.</div><div><br></div>

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