but remain unfrozen in the winter. The cool water of a spring and its branch may harbor species such as certain trout that are otherwise ill-suited to a warmer local climate. Types of mineral springs Sulfur springs contain a high level of dissolved sulfur or hydrogen sulfide in the water. Historically they have been used to alleviate the symptoms of arthritis and other inflammatory diseases. Borax springs Gypsum springs Saline springs Iron springs (chalybeate spring) Radium springs (or radioactive springs) have a detectible level of radiation produced by the natural radioactive decay process Uses Springs have been used for a variety of human needs - including drinking water, domestic water supply, irrigation, mills, navigation, and electricity generation. Modern uses include recreational activities such as fishing, swimming, and floating; therapy; water for livestock; fish hatcheries; and supply for bottled mineral water or bottled spring water. Springs have taken on a kind of mythic quality in that some people believe, falsely, that springs are always healthy sources of drinking water. They may or may not be. In order to know how to use a spring appropriately, whether for a mineral bath or drinking water one needs to access a comprehensive water quality test. Springs that are managed as spas will already have such a test. Drinking water Springs are often used as sources for bottled water. When purchasing bottled water labelled as spring water one can often find the water test for that spring on the website of the company selling it. Irrigation Springs have been used as sources of water for gravity-fed irrigation of crops. Indigenous people of the American Southwest built spring-fed acequias that directed water to fields through canals. This method was later used by the Spanish missionaries. Sacred springs A sacred spring, or holy well, is a small body of water emerging from underground and revered either some religious context: Christian and/or pagan and/or other. The lore and mythology of ancient Greece was replete with sacred and storied springs—notably, the Corycian, Pierian and Castalian springs. In medieval Europe, pagan sacred sites frequently became Christianized as holy wells. The term "holy well" is commonly employed to refer to any water source of limited size (i.e. not a lake or river, but including pools and natural springs and seeps), which has some significance in local folklore. This can take the form of a particular name, an associated legend, the attribution