Includes data and derivations not publicly available used to create figures and tables for manuscript. This dataset is associated with the following publication: Vanderhoof, M., J. Christensen, and L. Alexander. Influence of multi-decadal land use, irrigation practices and climate on riparian corridors across the Upper Missouri River headwaters basin, Montana. HYDROLOGY AND EARTH SYSTEM SCIENCES. EGS, 23(10): 4269–4292, (2019).

The Upper Missouri River headwaters (UMH) basin (36 400 km2 ) depends on its river corridors to support irrigated agriculture and world-class trout fisheries. We evaluated trends (1984–2016) in riparian wetness, an indicator of the riparian condition, in peak irrigation months (June, July and August) for 158 km2 of riparian area across the basin using the Landsat normalized difference wetness index (NDWI). We found that 8 of the 19 riparian reaches across the basin showed a significant drying trend over this period, including all three basin outlet reaches along the Jefferson, Madison and Gallatin rivers. The influence of upstream climate was quantified using per reach random forest regressions. Much of the interannual variability in the NDWI was explained by climate, especially by drought indices and annual precipitation, but the significant temporal drying trends persisted in the NDWI–climate model residuals, indicating that trends were not entirely attributable to climate. Over the same period we documented a basin-wide shift from 9 % of agriculture irrigated with center-pivot irrigation to 50 % irrigated with center-pivot irrigation. Riparian reaches with a drying trend had a greater increase in the total area with center-pivot irrigation (within reach and upstream from the reach) relative to riparian reaches without such a trend (p < 0.05). The drying trend, however, did not extend to river discharge. Over the same period, stream gages (n = 7) showed a positive correlation with riparian wetness (p < 0.05) but no trend in summer river discharge, suggesting that riparian areas may be more sensitive to changes in irrigation return flows relative to river discharge. Identifying trends in riparian vegetation is a critical precursor for enhancing the resiliency of river systems and associated riparian corridors.

The Upper Missouri River headwaters (UMH) basin (36 400 km2 ) depends on its river corridors to support irrigated agriculture and world-class trout fisheries. We evaluated trends (1984–2016) in riparian wetness, an indicator of the riparian condition, in peak irrigation months (June, July and August) for 158 km2 of riparian area across the basin using the Landsat normalized difference wetness index (NDWI). We found that 8 of the 19 riparian reaches across the basin showed a significant drying trend over this period, including all three basin outlet reaches along the Jefferson, Madison and Gallatin rivers. The influence of upstream climate was quantified using per reach random forest regressions. Much of the interannual variability in the NDWI was explained by climate, especially by drought indices and annual precipitation, but the significant temporal drying trends persisted in the NDWI–climate model residuals, indicating that trends were not entirely attributable to climate. Over the same period we documented a basin-wide shift from 9 % of agriculture irrigated with center-pivot irrigation to 50 % irrigated with center-pivot irrigation. Riparian reaches with a drying trend had a greater increase in the total area with center-pivot irrigation (within reach and upstream from the reach) relative to riparian reaches without such a trend (p < 0.05). The drying trend, however, did not extend to river discharge. Over the same period, stream gages (n = 7) showed a positive correlation with riparian wetness (p < 0.05) but no trend in summer river discharge, suggesting that riparian areas may be more sensitive to changes in irrigation return flows relative to river discharge. Identifying trends in riparian vegetation is a critical precursor for enhancing the resiliency of river systems and associated riparian corridors.

The data set contains measurement locations and measurements of daily and sub-daily water temperature, daily river discharge, and daily air temperature for several sites in the Upper Missouri River basin of Montana and North Dakota, 2001-2022. Water temperature sites include: the Missouri River upstream from Fort Peck Reservoir, Montana; multiple locations through a 351-km reach extending from Fort Peck Dam, Montana, downstream to near Williston, North Dakota; the lower reach of the Milk River, Montana; the lower reach of the Yellowstone River, North Dakota. River discharge data were obtained from USGS stream gages located in the study area and from the US Army Corps of Engineers. Air temperature data were obtained from NOAA weather stations in the study area. Water and air temperature data are presented in degrees Celsius. Discharge data are presented in cubic meters per second.

Collections of publically available secondary data used to develop the conclusions described in the journal article. This dataset is associated with the following publication: Faulkner , B., S. Leibowitz , T. Canfield , and J. Groves. Quantifying groundwater dependency of riparian surface hydrologic features using the exit gradient. Hydrological Processes. John Wiley & Sons, Ltd., Indianapolis, IN, USA, 1-11, (2015).

Collections of publically available secondary data used to develop the conclusions described in the journal article. This dataset is associated with the following publication: Faulkner , B., S. Leibowitz , T. Canfield , and J. Groves. Quantifying groundwater dependency of riparian surface hydrologic features using the exit gradient. Hydrological Processes. John Wiley & Sons, Ltd., Indianapolis, IN, USA, 1-11, (2015).

The dataset includes information to make Figures 1 through 6 of the manuscript. This dataset is associated with the following publication: Rajib, A., H. Golden, C. Lane, and Q. Wu. Surface Depression and Wetland Water Storage Improves Major River Basin Hydrologic Predictions. WATER RESOURCES RESEARCH. American Geophysical Union, Washington, DC, USA, 56(7): e2019WR026561, (2020).

The dataset includes information to make Figures 1 through 6 of the manuscript. This dataset is associated with the following publication: Rajib, A., H. Golden, C. Lane, and Q. Wu. Surface Depression and Wetland Water Storage Improves Major River Basin Hydrologic Predictions. WATER RESOURCES RESEARCH. American Geophysical Union, Washington, DC, USA, 56(7): e2019WR026561, (2020).

Paleohydrologic records provide a valuable perspective on the variability of streamflow and hydroclimate that is critical for water resource planning and placing present day and future conditions into a long-term context. Until now, key insights gained from streamflow reconstructions in the other river basins across the Western U.S. been lacking in the Upper Missouri River Basin due to a lack of extended streamflow records. Here we utilize a new database of naturalized streamflow records for the Upper Missouri and an expanded network of tree-ring records from the region to reconstruct streamflow at 31 gaging locations across the major Mountain Headwaters of the United States’ largest river basin. The database also includes an Upper Missouri Basin Basin composite record of streamflow that is not specific to any streamgage location, but rather summarizes streamflow variability across all the major gaging locations in the Upper Missouri River. The reconstructions explain an average of 68% of the variability in the observed streamflow records and extend records of streamflow to C.E. 886 on average. The network of streamflow reconstructions presented here fills a major geographical void in paleohydrologic understanding and provides important data resources to water managers balancing increasing water demands for hydropower, irrigation, navigation, and ecological resources with increasing flood risk in the basin.

Paleohydrologic records provide a valuable perspective on the variability of streamflow and hydroclimate that is critical for water resource planning and placing present day and future conditions into a long-term context. Until now, key insights gained from streamflow reconstructions in the other river basins across the Western U.S. been lacking in the Upper Missouri River Basin due to a lack of extended streamflow records. Here we utilize a new database of naturalized streamflow records for the Upper Missouri and an expanded network of tree-ring records from the region to reconstruct streamflow at 31 gaging locations across the major Mountain Headwaters of the United States’ largest river basin. The database also includes an Upper Missouri Basin Basin composite record of streamflow that is not specific to any streamgage location, but rather summarizes streamflow variability across all the major gaging locations in the Upper Missouri River. The reconstructions explain an average of 68% of the variability in the observed streamflow records and extend records of streamflow to C.E. 886 on average. The network of streamflow reconstructions presented here fills a major geographical void in paleohydrologic understanding and provides important data resources to water managers balancing increasing water demands for hydropower, irrigation, navigation, and ecological resources with increasing flood risk in the basin.