The Rio Chama Watershed has been built into a system for conserving and managing this runoff, and some of it from the San Juan Mountains in southern Colorado is diverted under the Continental Divide through the Azotea tunnel.
Lakes Heron, El Vado, and Abiquiu are prominent features.
The Rios Gallina, originating in the Nacimiento uplift and mountains east of Regina, now feeds into the Rio Chama.
Glaciation south from the San Juan Mountains, when combined with northwards flows down the Rio Gallina watershed, could have formed ice dams along today's Hwy 112 that helped to drive the Rio Gallina eastward.