Abstract. Detailed hydrometeorological data from the rain-to-snow transition zone in mountain regions are limited. As the climate warms, the transition from rain to snow is moving to higher elevations, and these changes are altering the timing of downslope water delivery. To understand how these changes impact hydrological and biological processes in this climatologically sensitive region, detailed observations from the rain-to-snow transition zone are required. We present a complete hydrometeorological dataset for water years 2004 through 2014 for a watershed that spans the rain-to-snow transition zone (https://doi.org/10.15482/usda.adc/1402076). The Johnston Draw watershed (1.8 km 2 ), ranging from 1497 to 1869 m in elevation, is a sub-watershed of the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho, USA. The dataset includes continuous hourly hydrometeorological variables across a 372 m elevation gradient, on north-and south-facing slopes, including air temperature, relative humidity, and snow depth from 11 sites in the watershed. Hourly measurements of incoming shortwave radiation, precipitation, wind speed and direction, soil moisture, and soil temperature are available at selected stations. The dataset includes hourly stream discharge measured at the watershed outlet. These data provide the scientific community with a unique dataset useful for forcing and validating hydrological models and will allow for better representation and understanding of the complex processes that occur in the rain-to-snow transition zone.

When deciding whether or not to regulate a chemical, regulatory bodies often evaluate the degree to which the public may be exposed by evaluating the chemical's occurrence in food and drinking water. As part of its decision-making process, the United States Environmental Protection Agency (USEPA) evaluated the occurrence of perchlorate in public drinking water by sampling public water systems (PWSs) as part of the first implementation of the Unregulated Contaminant Monitoring Rule (UCMR 1) between 2001 and 2005. The objective of this paper is to evaluate the current representativeness of the UCMR 1 dataset. To achieve this objective, publicly available sources were searched to obtain updated perchlorate data for the majority of large PWSs with perchlorate detections under UCMR 1. Comparison of the updated and UCMR 1 perchlorate datasets shows that the UCMR 1 dataset is no longer representative because the extent and degree of occurrence has decreased since implementation of UCMR 1. Given this finding, it seems appropriate for regulatory bodies engaged in decision-making processes over several years to periodically re-evaluate the conditions that prompted the regulatory effort, thereby ensuring that rules and regulations address actual conditions of concern.

Abstract. Detailed hydrometeorological data from the rain-to-snow transition zone in mountain regions are limited. As the climate warms, the transition from rain to snow is moving to higher elevations, and these changes are altering the timing of down slope water delivery. To understand how these changes impact hydrological and biological processes in this climatologically sensitive region, detailed observations from the rain-to-snow transition zone are required. We present a complete hydrometeorological dataset for water years 2004 through 2014 for a watershed that spans the rain-to-snow 5 transition zone (DOI:10.15482/USDA.ADC/1258769). The Johnston Draw watershed (1.8 km2), ranging from 1497 -1869 m in elevation, is a sub-watershed of the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho.The dataset includes continuous hourly hydrometeorological variables across a 372 m elevation gradient, on north-and south-facing slopes, including air temperature, relative humidity, and snow depth from 11 sites in the watershed. Hourly measurements of shortwave radiation, precipitation, wind speed and direction, and soil moisture and temperature are 10 available at selected stations. The dataset includes hourly stream discharge measured at the watershed outlet. These data provide the scientific community with a unique dataset useful for forcing and validating models and will allow for better representation and understanding of the complex processes that occur in the rain-to-snow transition zone.

Abstract. Detailed hydrometeorological data from the rain-to-snow transition zone in mountain regions are limited. As the climate warms, the transition from rain to snow is moving to higher elevations, and these changes are altering the timing of downslope water delivery. To understand how these changes impact hydrological and biological processes in this climatologically sensitive region, detailed observations from the rain-to-snow transition zone are required. We present a complete hydrometeorological dataset for water years 2004 through 2014 for a watershed that spans the rain-to-snow 5 transition zone (doi 10.15482/USDA.ADC/1402076). The Johnston Draw watershed (1.8 km 2 ), ranging from 1497 -1869 m in elevation, is a sub-watershed of the Reynolds Creek Experimental Watershed (RCEW) in southwestern Idaho, USA. The dataset includes continuous hourly hydrometeorological variables across a 372 m elevation gradient, on north-and southfacing slopes, including air temperature, relative humidity, and snow depth from 11 sites in the watershed. Hourly measurements of incoming shortwave radiation, precipitation, wind speed and direction, and soil moisture and temperature 10 are available at selected stations. The dataset includes hourly stream discharge measured at the watershed outlet. These data provide the scientific community with a unique dataset useful for forcing and validating models and will allow for better representation and understanding of the complex processes that occur in the rain-to-snow transition zone.

Supplemental Information: Table 1: Date of initiation of snowpack, melt out date and the number of days with snow on the ground for each WY. Gaps in the snow depth record are documented as well. A smoothing window of 8 hours was applied to all WYs.