The Stillaguamish River, located in northwest Washington, is a vital regional water supply and a critical salmon habitat. Peak flows in the Stillaguamish River have been increasing due to forest harvesting and long-term climate warming trends.  As temperatures continue to warm, a greater proportion of winter precipitation will fall as rain rather than snow, resulting in reduced snowpack and snowlines that recede to higher elevations. These trends will result in greater peak flows at higher elevations and increased risks for salmon habitat, farmland, and municipal flood control systems.

Previous efforts to assess changes in peak flows (using statistically-downscaled meteorological data inputs) have been shown to under predict peak winter flow amounts. This research will use meteorological data derived from newly-available regional climate simulations and a hydrology model to better quantify winter peak flows in the Stillaguamish River. The information about projected future peak flows from this project will provide actionable data to assist watershed managers in mitigating climate-change related flooding in the Stillaguamish River basin.

James’ research aims to assist watershed managers in mitigating climate-change related flooding in the Stillaguamish River basin by developing better estimates of the size of future high streamflow events, using newly-available regional climate model projections of future local climate change.