The basin has a continental-type climate modified by topography, in which there are large temperature ranges and irregular seasonal and annual precipitation. Areas along the Continental Divide average 30 in. or more of precipitation annually, which includes snowfall in excess of 300 in. Most of the precipitation on the plains occurs as rain, which falls between April and September, while most of the precipitation in the mountains occurs as snow, which falls during the winter. The three-State area of the South Platte River Basin has about 2.4 million people, over 95 percent of whom live in Colorado. Population densities outside the urban corridor are small, centered in small towns located along the principal streams.
Rangeland is present across all areas of the basin except over the high mountain forests.
Co. Forest land occurs in a north-south band in the mountains. Urban or built-up land is present primarily in the Front Range urban corridor. Barren lands primarily are areas under construction or are areas of strip mining, quarries, or gravel pits. Standards have not been met in surface water for dissolved oxygen and un-ionized ammonia. Ground water in shallow alluvial aquifers has been determined in some areas to contain concentrations of nitrate in excess of the drinking-water standard.