The Trinity Watershed (HUC 18010211) is located in Northern California and covers an area of approximately 3,745 square miles. The watershed is characterized by rugged terrain, with elevations ranging from 2,000 to 8,000 feet above sea level. Snowpack is a significant contributor to the watershed, as it provides the majority of the surface water during the dry months. The Trinity River is the primary surface water source for the watershed, with several smaller streams and tributaries also contributing to the overall water supply. The two primary reservoirs in the watershed, Trinity Lake and Lewiston Lake, are used for water storage, flood control, and hydroelectric power generation. The watershed has experienced notable climate trends in recent years, including reduced snowpack and increased summer temperatures. These trends have led to changes in the hydrology of the watershed, including shifts in the timing and volume of streamflow.