The Lower Chehalis Watershed, located in western Washington state, covers approximately 1,360 square miles. The area is characterized by a diverse range of aquatic and terrestrial habitats, including estuaries, wetlands, forests, and grasslands. The watershed is fed by the Chehalis River and several tributaries, which originate from the Olympic Mountains and the Willapa Hills. Snowpack in the region is typically light and melts quickly, contributing to the river's flow. The watershed supports a variety of fish and wildlife, including salmon, steelhead, and orca whales. Reservoirs within the watershed are primarily used for flood control and irrigation. The region experiences a mild, rainy, marine climate, with average temperatures ranging from the mid-40s to low-60s Fahrenheit. Over the past few decades, the watershed has experienced an increase in stormwater runoff and sedimentation, leading to degraded water quality and habitat loss. Efforts are underway to restore and protect the watershed's ecological health.