The Lower James Watershed (HUC 10160011) covers an area of 6,595 square miles in South Dakota and Iowa. The hydrology of the watershed is dominated by the James River, which flows for 710 miles before emptying into the Missouri River. The area receives an average of 24 inches of precipitation annually, with much of it coming in the form of snow. The snowpack typically peaks in early March and begins to melt in mid-April. Surface water in the watershed is used for irrigation, drinking water, and recreation. The largest reservoir in the watershed is Lake Madison, which was constructed in 1955. Interesting climatic facts and trends include an increase in average temperatures over the past century and more frequent and intense precipitation events. These trends are expected to continue in the coming decades, which could impact the hydrology and ecology of the watershed.