Stream temperature influences the growth, abundance, distribution, timing of life history events, and survival of Pacific salmon. Over the past 60 years, Alaska has warmed at more than twice the rate of the lower 48 states and warm water temperatures can impact cold-water fish survival and increase the spread of diseases and non-native species. As climate continues to change, linking baseline monitoring with predictive models to map thermal habitats will provide a means for better understanding species distributions, thermal optimums, and non-native invasions; and informing management of critical habitats. This project links stream temperature monitoring efforts previously funded by the Mat-Su Basin Salmon Habitat and Kenai Peninsula Fish Habitat partnerships with the USGS National Hydrography Dataset and State of Alaska’s Anadromous Waters Catalog to develop stream temperature models for the Deshka River, Anchor River, Stariski Creek, and Kenai River watersheds. Existing climate, hydrology, and land-cover spatial datasets were used to predict daily stream temperatures. The objectives for this project included (1) building statistical models to predict daily stream temperatures from June 1 to September 15 over the historical period 1980- 2019, (2) predicting future changes in stream temperature based on estimated increases in air temperature, (3) calculating metrics useful for describing stream thermal regimes for historic period and future climate scenarios, (4) and summarizing thermal regimes for Chinook Salmon and Coho Salmon life-history specific habitats.

About the data
Data required to develop the stream temperature models and model outputs are provided separately as zip files for each watershed: Deshka, Anchor-Stariski, and Kenai. Input data include stream reach and catchment shapefiles, monitoring site locations, temperature data, spatial variables, and climate variables. Output data products include predicted mean daily stream temperatures over a historical period (1980-2019) in addition to predictions for two future climate scenarios. A suite of annual stream temperature metrics was calculated for both sets of predictions. Due to limited empirical temperature data, the stream temperature model for the Kenai River was not used to make predictions. Input data for this watershed are provided in the kenai.zip file.

Acknowledgements
Funding for this project was provided by the U.S. Fish and Wildlife Service on behalf of the Mat-Su Basin Salmon Habitat Partnership and the Kenai Peninsula Fish Habitat Partnership. The report authors would like to thank Jon Gerken, Dan Rinella, Ben Rich, Mary Kate Swenarton and other staff at the U.S. Fish and Wildlife Service for sharing temperature data from the Deshka River watershed and discussing ideas for this analysis along the way; Steve Baird and staff at the Kachemak Bay National Estuarine Research Reserve for sharing temperature data from the Anchor River and Stariski Creek watersheds; John Hagan, a former graduate student at Alaska Pacific University, for sharing temperature data from the Anchor River watershed; and Ben Meyers, a former graduate student at the University of Alaska Fairbanks, for sharing data from the Kenai River watershed.