Final Answer:
The group with the largest prehistoric irrigation works north of the Andes is the Norte Chico civilization in present-day Peru. They developed intricate irrigation systems around 3200 BCE, which is the oldest in the Americas.
Step-by-step explanation:
The Norte Chico civilization, also known as the Caral-Supe civilization, flourished along the central coast of Peru. They constructed impressive irrigation systems that allowed them to cultivate crops in arid coastal regions. These irrigation works are considered the largest prehistoric ones in the Americas, specifically north of the Andes.