The irrigation canal system was constructed for large scale cultivation of maize (corn). Its discovery pushed back the dates previously established for large scale agriculture in the U.S. by a thousand years.
Because of the discovery of the Las Capas site it is now known that there was sophisticated farming here during the Late Archaic-Early Agricultural (1,200 B.C.E. - back) period, and it is speculated that evidence of even older large scale farming at this same location will be discovered. This is one of the reasons why this area received the Santa Cruz Valley National Heritage Area designation in 2018.
Continuing discoveries in Marana paint a picture of a populated area along the Santa Cruz River that was nearly continuously occupied from 13,000 years B.C.E. to present, and part of a vast cultural network that stretched to South America and across the United States. The Late Archaic cultures up to the Hohokam cultures (1200 B.C.E. - 1,200 A.D.) here were based around farming many types of crops. About 1,000 years ago, the Hohokam (who also farmed maize) farmed agave using specialized rock constructs to grow agave murpheyi for food, fiber, and possibly trade. This type of agave doesn't naturally grow in the desert floor region on poor rocky bajada soil. Clever farming strategies allowed for the cultivation of as many as 42,000 agave plants at one 1,200 acre farm site in the Marana area.