Water stable isotope data (hydrogen and oxygen isotopes of H2O) for 5 river basins in Washington state and Alaska. The samples were collected in 2017 during summer baseflow season. Collection sites were distributed across each basin to represent the range of possible isotope values within the basin, but sample sites were easily accessible. This dataset is associated with the following publication: McGill, L., E.A. Steel, J.R. Brooks, R.T. Edwards, and A. Fullerton. Elevation and spatial structure explain most surface-water isotopic variation across five Pacific Coast basins. JOURNAL OF HYDROLOGY. Elsevier Science Ltd, New York, NY, USA, 583: 124610, (2020).

Water stable isotope data (both hydrogen and oxygen isotopes of H2O) from the Snoqualmie River Basin from 2017-2018. This data was paired with USGS gauge data so includes watershed characteristics at the gaging stations near where water isotopes were collected. Water isotopes were collected throughout the basin to cover the range of elevation and stream sizes. Water isotopes were collected 5 times at all locations, and approximately twice monthly at the main stem of the Snoqualmie and larger tributaries. This dataset is associated with the following publication: McGill, L., J.R. Brooks, and A. Steel. Spatial and temporal dynamics of water sources in a mountain river basin inferred through δ2H and δ18O of water. Hydrological Processes. John Wiley & Sons, Ltd., Indianapolis, IN, USA, 35(3): e14063, (2021).

Water stable isotope data (both hydrogen and oxygen isotopes of H2O) from the Snoqualmie River Basin from 2017-2018. This data was paired with USGS gauge data so includes watershed characteristics at the gaging stations near where water isotopes were collected. Water isotopes were collected throughout the basin to cover the range of elevation and stream sizes. Water isotopes were collected 5 times at all locations, and approximately twice monthly at the main stem of the Snoqualmie and larger tributaries. This dataset is associated with the following publication: McGill, L., J.R. Brooks, and A. Steel. Spatial and temporal dynamics of water sources in a mountain river basin inferred through δ2H and δ18O of water. Hydrological Processes. John Wiley & Sons, Ltd., Indianapolis, IN, USA, 35(3): e14063, (2021).

Water stable isotope data (hydrogen and oxygen isotopes of H2O) from wetlands and streams within the Pipestem Creek watershed. This data was collected over two open water seasons (May-September): 2014 and 2015. This dataset is associated with the following publication: Brooks, J.R., D. Mushet, M. Vanderhoof, S. Leibowitz, J. Christensen, B. Neff, D. Rosenberry, W. Rugh, and L. Alexander. Estimating wetland connectivity to streams in the Prairie Pothole Region: an isotopic and remote sensing approach. WATER RESOURCES RESEARCH. American Geophysical Union, Washington, DC, USA, 54(2): 995-977, (2018).

In this data release, hydrogen-2 and oxygen-18 isotope ratios are presented for 158 unique sites in central and eastern Washington. There are 16 unique surface water sites with a total of 140 samples, and 142 groundwater sites with a total of 167 samples. Sample dates range from February 1993 to February 2021. Stable isotope analysis of water utilizes slight differences in the mass of water molecules due to naturally occurring stable isotopes of oxygen and hydrogen replacing the lighter and more common oxygen-16 and hydrogen-1. These differences in water molecule mass influence behavior during physical processes within the hydrologic cycle, such as evaporation and condensation. These mass differences lead to isotopic fractionation, where the lighter isotopes (for example: oxygen-16 and hydrogen-1) are preferentially enriched in the vapor phase, while the heavier isotopes (for example: oxygen-18 and hydrogen-2) are enriched in the liquid phase. The extent of fractionation is controlled by local factors such as temperature, relative humidity, and distance from the ocean which, combined, create an isotopic signature. Measuring these variations in isotopic ratios caused by local processes can be valuable for identifying groundwater sources and understanding hydrologic connectivity and flow paths in regional systems (Clark and Fritz, 1997). Stable isotopes of water (hydrogen-2 and oxygen-18) are particularly useful as groundwater tracers because they are part of the water molecule and move unhindered within the aquifer matrix. In addition to conservative transport, hydrogen-2 and oxygen-18 mix conservatively and can be used to assess mixture ratios of water parcels from distinct sources. References cited: Clark, I.D., and Fritz, P., 1997, Environmental Isotopes in . CRC Press, 342p, https://doi.org/10.1201/9781482242911

Water stable isotope ratios (2H and 18O) from the Willamette River Basin in Oregon, USA. Isotope values in the Willamette River are from both Portland and Corvallis Oregon, and were collected once or twice a month for 13 years (2011 - 2013). Isotope data are provided for small spatially distributed watersheds across the basin and samples were collected once a year during summer lowflow, and used to test the temporal stability of the Willamette River Basin Isoscape developed in the following paper: Brooks, J. R., Wigington, P. J., Phillips, D. L., Comeleo, R., & Coulombe, R. (2012). Willamette River Basin surface water isoscape (d18O and d2H): temporal changes of source water within the river. Ecosphere, 3(5), 39. doi: http://dx.doi.org/10.1890/ES11-00338.1 In addition, precipitation isotopes from Corvallis and Newport were collected weekly.

Stable water isotopes of precipitation across the USA and from summer and winter. Additionally isotopic data was included for river water within the Willamette River in Oregon. The d18O and d2H were previously published data (references given in the table), while the d17O values were measured on those archived samples, and published in this paper.

Water stable isotope data collected from a range of streams throughout the Marys River basin in water year 2015, and precipitation data collected within the basin at a range of elevations. This dataset is associated with the following publication: Nickolas, L., C. Segura, and J.R. Brooks. The influence of lithology on surface water sources. Hydrological Processes. John Wiley & Sons, Ltd., Indianapolis, IN, USA, 31(10): 1913-1925, (2017).

The dataset includes water isotope values from samples spatially distributed across the Snake River basin collected between 2013-2015, and time series data collected from the Snake River at King Hill. The timeseries data were collected at the USGS 13154500 gage at approximately monthly intervals from 2013 through water year 2019. Site descriptions and watershed metrics are also included for the spatially distributed collection sites. Water Isotope QA data has also been included. This dataset is associated with the following publication: Windler, G., J.R. Brooks, H.M. Johnson, R. Comeleo, R. Coulombe, and G. Bowen. Climate Impacts on Source Contributions and Evaporation to Flow in the Snake River Basin Using Surface Water Isoscapes (δ2H and δ18O). WATER RESOURCES RESEARCH. American Geophysical Union, Washington, DC, USA, 57(7): e2020WR029157, (2021).