According to records of the National Weather Service (formerly the U.S. Weather Bureau) for a station near Syracuse, the average annual precipitation in Hamilton County is about 16 inches. Of this amount, 83 percent occurs during the growing season (March 15 to October 15). A part of the precipitation runs off as surface flow, part is evaporated, part is used by vegetation, and a small part percolates downward to recharge the ground-water reservoir. The average recharge from precipitation for Hamilton County is estimated to be 0.1 inch per year. Owing to the limited supply of water in most of the upland area of the county, dryland farming and grazing are the predominant land uses.