An easy shoreline and canyon-mouth walk at the San Blas reservoir, the entrance to a barranca system that runs more than 50 km up into the Sierra Fria with vertical walls up to 70 m high. Strong birdlife on the reservoir, and the Museo de la Insurgencia in the village makes an obvious pairing.
The Presa de San Blas sits beside Pabellon de Hidalgo in Rincon de Romos municipality, in the flat farming country of northern Aguascalientes, and its significance for walkers is what lies immediately upstream. The reservoir marks the mouth of a barranca system that runs more than 50 km back into the Sierra Fria, with walls reaching around 70 metres in places. This route is the approach rather than the full canyon: about 7 km round trip with roughly 150m of cumulative gain, taking two and a half to three hours, following the shoreline to the canyon mouth and a short distance into it before turning back.
Access is comparatively easy by regional standards. Drivers take the highway north from Aguascalientes city, around 45 minutes; those without a vehicle can take a Rincon de Romos bus from the Central de Autobuses and then a short taxi to the dam, one of the few hikes in the state reachable by public transport. Parking is informal near the dam and no fee, gate or permit applies to the shoreline.
Underfoot the walking is straightforward: compacted dirt tracks and gravel around the reservoir margin, then stonier ground and dry streambed gravel as the walls begin to close in at the canyon mouth. Shade is minimal along the open shoreline and improves sharply once inside the barranca, where the rock walls cut the sun for much of the day. There is no scrambling on the section described, and the sensible turn-around is the point where the streambed narrows and progress starts to require route-finding over boulders.
Birdlife on the reservoir is the standout: herons, egrets, cormorants and wintering ducks gather in the shallows, and binoculars are on most packing lists for good reason. The Museo de la Insurgencia in Pabellon de Hidalgo, housed in the hacienda where Miguel Hidalgo was stripped of his command in 1811, sits a few minutes away and makes the obvious pairing for the rest of the day. The canyon system floods after summer storms, so October to April is the window; there is no potable water, no shelter and no refuge anywhere on the route, and supplies should be bought in Pabellon de Hidalgo or Rincon de Romos beforehand.
Trail facts
- Trail area
- Pabellon de Hidalgo, Municipio de Rincon de Romos, Aguascalientes
- Best season
- October to April; the canyon system floods after summer storms
What to bring
- Trail shoes
- 2 litres of water
- Binoculars for waterbirds
- Sun protection
Location
Presa de San Blas, Pabellon de Hidalgo, Rincon de Romos, Aguascalientes, Ags., Mexico
22.1476, -102.2841 View on map
Highlights
- The mouth of a barranca system running more than 50 km into the Sierra Fria, with walls up to 70 metres high
- Strong reservoir birdlife, including herons, egrets, cormorants and wintering ducks in the shallows
- Cool, shaded walking inside the canyon after the exposed shoreline approach
- One of the few Aguascalientes hikes reachable by public transport via a Rincon de Romos bus
- The Museo de la Insurgencia in Pabellon de Hidalgo nearby, where Miguel Hidalgo lost his command in 1811
Tips for visiting
- Take a Rincon de Romos bus from the Central de Autobuses and a short taxi to the dam if driving is not an option.
- Avoid the route after summer storms; the canyon system floods and the streambed becomes dangerous.
- Bring binoculars. The shallow reservoir margins hold the densest waterbird concentrations from November to February.
- Turn back where the streambed narrows and boulder route-finding begins, unless equipped for a longer canyon day.
- Buy water and food in Pabellon de Hidalgo or Rincon de Romos; nothing is sold at the dam itself.
- Pair the walk with the Museo de la Insurgencia in the village, a few minutes away, to fill out the day.
When to visit
October to April, outside the flood season, with mild temperatures on the exposed shoreline. Early morning brings the best birdwatching on the reservoir and the coolest walking before the canyon walls warm through.
Accessibility
Sections of the dirt and gravel track near the dam are level and firm enough for an all-terrain stroller in dry conditions, but the surface is unsealed throughout and the canyon-mouth ground is stony and uneven. The route is not suitable for wheelchairs, and there are no accessible toilets or facilities at the reservoir.
Frequently asked questions
How far does the canyon system extend?
The barranca runs more than 50 km upstream into the Sierra Fria, with walls reaching around 70 metres. This route covers only the reservoir shoreline and the canyon mouth, about 7 km round trip.
Can the dam be reached without a car?
Yes. A Rincon de Romos bus from the Central de Autobuses in Aguascalientes city, followed by a short taxi, reaches the dam. This makes it one of the more accessible hikes in the state.
When should the route be avoided?
During and immediately after summer storms from roughly June to September, when the canyon system floods. October to April is the reliable window.
Is any scrambling involved?
Not on the section described. The route stays on shoreline tracks and easy streambed gravel, turning back where narrowing walls and boulders would start to demand route-finding.
What else is worth visiting nearby?
The Museo de la Insurgencia in Pabellon de Hidalgo occupies the hacienda where Miguel Hidalgo was relieved of command in 1811, and sits only a few minutes from the dam.