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Meet the Watershed

Geography, Geology, and Climate Past and Present

A watershed or drainage area is an expanse of land in which all surface waters drain to a common point. This makes Embudo – ‘funnel’ in Spanish – perhaps the most appropriately named watershed on Earth.

Map of the Rio EMbudo Watershed 6:8

For the Rio Embudo Watershed, this common drainage point is the junction of the Rio Embudo and the Rio Grande, and the drainage area stretches east, northeast, and southeast of this confluence. All rivers, streams, and non-evaporated precipitation within the bounds of the watershed eventually reach the Rio Grande at Embudo. The Rio Embudo itself becomes the centerpiece of the watershed close to its mouth, but upstream, other rivers and streams participate in the drainage system: the Rio Santa Barbara, Rio Pueblo, Rio Chiquito and Trampas Creek. Their confluence near Picurís Pueblo makes up the Rio Embudo’s source.

The watershed descends 7,000 feet from its highest point at North Truchas Peak (elevation 13,100 feet) to the confluence with the Rio Grande (elevation 6,000 feet). Its boundaries are not a clean circle around these points, but rather a circuitous route that encompasses two valleys and over one dozen communities. As with many drainage areas, portions of the boundaries of the Rio Embudo Watershed are used as political borders.  The watershed's northern boundary matches the Rio Arriba/Mora County line until it turns northeast into the Taos/Mora County line, and then traces the foot of the Sangre de Cristo Mountains. At the Rancho del Rio Grande Land Grant border, the watershed boundary turns southwest until it curves around Gallegos Peak and runs northwest through the Picurís Mountains back to the confluence of the rivers. Within the upstream portion of this area, contemporary communities include Placita, Vadito, Llano de la Yegua, Rodarte, Llano de San Juan, Peñasco, Chamisal, Las Trampas Truchas, Rio Lucio, and Picurís Pueblo. The Embudo Valley downstream houses Ojo Sarco, Cañoncito, Apodaca, Dixon, and Embudo. Before the early 18th century, the lands traditionally used by Northern Tiwa-speaking Picurís Pueblo stretched further west down the watershed into the Embudo Valley; in 1725, Picurís was restricted to lands upstream after the Spanish colonial government rejected their claims.

Between 1.8 billion and 3 million years ago, rock units formed from both volcanic and sedimentary deposits in the area that would eventually become the Rio Embudo Watershed. Over time, ancestral versions of the watershed’s streams and rivers carved space into the rock, creating the diverse landforms that characterize the watershed today. In the Peñasco and Dixon valleys, these rocks belong to the Santa Fe group – a geologic stratum comprised of basalts, ash, and sediments. The canyon surrounding the Rio Pueblo, on the other hand, was cut into Pre-Cambrian granites, quartzites, schists, and amphibolites. Near the headwaters of the Rio Embudo, the top strata are sedimentary beds deposited by ancient rivers that flowed east around 300 million years ago.

Above the layers of rock, the Rio Embudo and its source waters feed vegetation that are commonly divided into four zones in the contemporary era. Above 11,000 feet, alpine grasslands cover Jicarilla Peak, La Jicarita Peak, and the area around Hidden and Trampas Lakes with sparse and slow-growing grasses and shrubs. The spruce-fir zone (8,500 feet – 11,000 feet) covers much of the Pecos Wilderness. The pine zone (7,500 feet – 8,500 feet) corresponds roughly with the upstream portion of the watershed, while the piñon-juniper-brush zone (6,000 – 7,500 feet) blankets the Embudo Valley and parts of Picurís Pueblo. The latter two zones support the vast majority of the watershed’s contemporary human communities and are ecologically more fertile, even though they receive substantially less rainfall. The Embudo Valley receives only 12 inches of rain per year and must be irrigated by ten historic acequias.

Before about 2000 BCE, however – when the Rio Embudo Watershed’s ecology and climate began to look similar to the contemporary one – the local environment was quite different. The end of the last glacial period in North America (10,000 BCE) brought significant climatic warming to the Southwest, along with substantial summer rainfall. At the moment of arrival of the Southwest’s first people, the region’s lowlands were covered in lush grasslands that supported the bison and other megafauna they hunted. The low-elevation mountains common to the Northern Rio Grande were blanketed in desertscrub plant species. In 8000 BCE, the climate was beginning to get warmer and drier, but the rivers and streams of the watershed would have provided ample waters for groups of people and large mammals alike. By 6000 BCE, the Southwestern environment had become considerably patchy. Some geologists and paleoecologists reconstruct a seasonal climate of hotter, wetter summers and cooler, drier winters; others believe this period became uniformly hotter and more arid across all seasons. Either way, the expansive grasslands of the past were gone and desertscrub largely took its place. The uplands became forests of juniper and piñon, while ponderosa pine woods lived at high elevations.

Over the next four centuries, the climate of the Northern Rio Grande shifted to reach the semi-arid continental environment that persists into the 21st century.