Peoria Mineral Springs, on Peoria’s West Bluff, is a naturally flowing spring estimated to be more than 14,500 years old and a remnant of glacial retreat from the last Ice Age. Long used by Indigenous people, as shown by archaeological finds, it later became important to Peoria’s growth and industry. In 1834, a brick reservoir collected its water for the early Peoria Water Works, which carried water through wooden pipes for miles. The spring also supported a bottling business by the late 19th century. Saved from demolition in 1969 and later reopened after excavation, it remains significant for its geological age and its links to Indigenous use, public water supply, and local commerce.