The most iconic spot on the entire U.S./Mexico border is the Santa Elena Canyon at Big Bend National Park.

Over millions of years, the canyon walls were carved by the flow of the Rio Grande. Now, the river that carved the canyon has been turning into a dry riverbed.

The walls of the canyon serve as the division line between both countries.

Upriver from the Santa Elena Canyon is where the Rio Grande meets the Rio Conchos, a Mexican river at the historic town of Presidio.

Water from that Mexican river is the water we depend on from Mexico, and very little of it is coming downstream.

Channel 5 News Photojournalist Israel Almeida contributed to this report.

Watch the video above for the full story.