Arizona is abundant in water and metals, such as gold, copper and silver. Most of the copper mining in the United States takes place in Arizona; its rich copper deposits exceed all of the other states' copper deposits combined.
Arizona operates one of the most effective irrigation systems in the world, resulting in the state's ability to produce quality crops such as lettuce, cotton, citrus and grain despite its arid climate. The Colorado River and the water from lakes, rivers and streams are some of the state's surface water sources. Roughly 43 percent of its drinking water are taken from groundwater sources, which are found underneath the ground in natural reservoirs known as aquifers. The state uses effluent or treated water in agriculture, water parks, golf courses, maintenance of national parks and industrial cooling.
Although Arizona mostly has a desert environment, it also has an arable land and has natural forests that once supported its timber industry. About 19 percent of the total forested area in the state is considered commercial and reserved for the production of industrial timber products. The lumber industry in Arizona was active in the 19th century, but it dwindled in the 1990s due to environmental and overharvest litigation.