1970's Barquero, was at the time unusual for LVC as it was an American production filmed entirely in Colorado. Much of the action took place at the Brush Hollow Reservoir located in Penrose, Colorado.
I visited this location twice, once in 2014 and again in 2015 to try to track down the Barquero locations. This was particularly challenging as the terrain and water level has changed drastically in the past 45 years, making it virtually impossible to identify any locations from one side of the "river" as featured in the movie.
As featured in the film, the story takes place on the Parla River, with the small settlement of Lonely Dell on one side, and quicker access to Mexico on the other. The bulk of the story has LVC's Travis on the "Mexican" side, and Warren Oates' Remy on the Lonely Dell side. There is nothing left identifiable on the "Mexican" side aside from landscape shots of the plateau in the background. The Lonely Dell side yields slightly more identity as the bank of the settlement can be exactly pinpointed.
A few comparisons below-
Travis arrives in Lonely Dell
Later in the film Remy is on the Lonely Dell side
Finale - Travis returns to the Lonely Dell side. Notice the outhouse behind LVC is an actual public restroom today.
Travis stares down Remy. Dock area on the "Mexican" side has completely grown over in the past 45 years.
Additional photos - "Mexican" side (nothing left to screen match)
Additional photos - Lonely Dell side