The NorWeST Summer Stream Temperature Model and Scenarios for the Western U.S.: A Crowd‐Sourced Database and New Geospatial Tools Foster a User Community and Predict Broad Climate Warming of Rivers and Streams

Abstract

Thermal regimes are fundamental determinants of aquatic ecosystems, which makes description and prediction of temperatures critical during a period of rapid global change. The advent of inexpensive temperature sensors dramatically increased monitoring in recent decades, and although most monitoring is done by individuals for agency‐specific purposes, collectively these efforts constitute a massive distributed sensing array that generates an untapped wealth of data. Using the framework provided by the National Hydrography Dataset, we organized temperature records from dozens of agencies in the western U.S. to create the NorWeST database that hosts >220,000,000 temperature recordings from >22,700 stream and river sites. Spatial‐stream‐network models were fit to a subset of those data that described mean August water temperatures (AugTw) during 63,641 monitoring site‐years to develop accurate temperature models (r2 = 0.91; RMSPE = 1.10°C; MAPE = 0.72°C), assess covariate effects, and make predictions at 1 km intervals to create summer climate scenarios. AugTw averaged 14.2°C (SD = 4.0°C) during the baseline period of 1993–2011 in 343,000 km of western perennial streams but trend reconstructions also indicated warming had occurred at the rate of 0.17°C/decade (SD = 0.067°C/decade) during the 40 year period of 1976–2015. Future scenarios suggest continued warming, although variation will occur within and among river networks due to differences in local climate forcing and stream responsiveness. NorWeST scenarios and data are available online in user‐friendly digital formats and are widely used to coordinate monitoring efforts among agencies, for new research, and for conservation planning.

Variable hybridization outcomes in trout are predicted by historical fish stocking and environmental context

“…Environmental variables included were mean modelled August stream temperature, precipitation, basin size, slope, canopy cover, elevation, and aspect. We acquired data for all of these variables except aspect from the NorWeST Stream Temperature Regional Database (Isaak et al, ), which uses historical temperature data and climate models to project current and future water temperatures. We selected the modelled point closest to our fish sampling location, and checked these points visually by plotting both sampling locations and points for modelled data on a shapefile of streams in the North Fork Shoshone River basin.…”

Historical and Future Stream Temperature Change Predicted by a Lidar‐Based Assessment of Riparian Condition and Channel Width

“…; Isaak et al. ). For each transect in the riparian inventory, we appended values from three predicted scenarios from the closest NorWeST model data location.…”

Influence of landscape and hydrological factors on stream–air temperature relationships at regional scale

“…Streams with wetter basin (high P and low PET) are expected to have higher water yields and more groundwater contributions that should cool streams (Isaak et al, 2017). Streams with wetter basin (high P and low PET) are expected to have higher water yields and more groundwater contributions that should cool streams (Isaak et al, 2017).…”

“…On small and medium streams, it is necessary to preserve and/or favour the presence of riparian vegetation to moderate TS (Fabris, Malcolm, Buddendorf, & Soulsby, 2018). The effects will be most pronounced, in comparison with large streams, because of their smaller width, but investments have to be made strategically (Isaak et al, 2017;Johnson & Wilby, 2015). From a watershed management perspective, stream shading would be less effective in streams where…”