Exploring the Thermal Regime of the Snoqualmie River Watershed, Washington Via Air and Stream Temperature Correlations

Various aspects of natural stream temperature regimes influence the ecological and biological health of stream networks by affecting the phenology of aquatic insects and fishes. Multiple techniques can be employed to model stream temperatures. Models that correlate stream and air temperatures often utilize a singular source of air temperature, ignoring variations throughout the network. This study compares localized relationships between air and stream temperatures throughout a stream network. Air (n=12) and water (n=12) temperature loggers were deployed in the Snoqualmie River Watershed, Washington State, USA, recording synchronized data in 30 min increments.  To summarize these data, we designed metrics that capture particular facets of air temperature, stream temperature, and their relationship that may have significance to ecosystem functioning. Metrics such as degree day’s accumulated, daily range and maximum temperature were correlated. The degree of correlation between air and water temperatures and the warming and cooling pattern within a 24 hour period varied with location. Climate change will influence various aspects of both air and stream thermal regimes, understanding the complexity of those relationships can facilitate better river management.