He placed the period of these remains at 2000 B.C. to 200 A.D. He said the investigators only hit what appears to be the canal “in one trench.” The apparent canal had a U-shaped channel containing a layer of burnt charcoal, which he said is pretty common for these canals. Workers also recovered an aquatic bird bone from there.

“Everything seems to suggest canal, but we want to get more confidence in it,” he said.

This canal could be, but probably isn’t, older than the region’s earliest canals, dating to 1500 to 1000 B.C., said Huckleberry, who placed this canal’s age at 1000 B.C. to 1 A.D.

“The reason I say that is that the other canals that were identified just a little bit west of I-10 date to that time period,” Huckleberry said. “We’re east of I-10.”

Discovery of this and similar sites, all along the Santa Cruz River, represent an archaeological milestone for this region, said Linda Mayro, Pima County’s director of conservation and sustainability.

Archaeologists have only begun to understand in the last 15 years or so that communities lived along the river up to 4,000 or more years ago, she said. Particularly important is that these communities had irrigated agriculture, usually growing corn, she said.