Where’s the Marsh?

The heart of San Sebastian "Marsh." The larger trees are mesquite, smaller shrubs are creosote bush, salt cedar is invading the arroyos. Google Earth Image

In gratitude, Anza named the site for the Indian Sebastian Taraval, nicknamed Peregrino (the wanderer), who successfully led them here to water.

“To this site I gave the name of Zienega de San Sevastian, alias del Peregrino. In the place where we halted there is a good spring of very potable water, and there are many others to the west which are saline. From them is formed a marsh more than a league long with plentiful pasturage, although it is likewise salty.” –Juan Bautista de Anza, March 10, 1774; translated by Herbert Bolton, 1930; underlines ed.

One of the themes of our research is linguistic. Much of the Spanish-language vocabulary used by the explorers and colonists included words with obsolete spelling conventions and words that do not have good English-language equivalents. The English language is a product of Northern Europe where there are wet summers and an old, stable, mature terrain. Spanish is a product of the Mediterranean and Northern Africa, which, like California, is summer dry, and has a tectonically active, young, immature terrain. It is not surprising that the Spanish vocabulary for aquatic features is better attuned to many features of California and the desert southwest than is the English vocabulary. This is a good opportunity to take a moment to look at how our preconceptions of both language and terrain have influenced our reconstructions of history and historical ecology.

The Anza quote is a perfect example of the linguistic issues. The first issue is the simple issue: in modern Spanish, Zienega de San Sevastian becomes Ciénaga de San Sebastian. The second one is the real problem. Bolton, as others would have, translated Zienega as “marsh.” In our explorations of this fantastic ecosystem, a nagging question remained: where’s the marsh? Answer: Ciénaga does not translate into English; what we saw we would not call a vast marsh.

As currently defined in Wikipedia:

A cienega or cienaga (in modern Spanish ciénaga) is a Spanish Colonial term for a spring, that is in use in English in the southwestern United States. A cienega usually is a wet, marshy area at the foot of a mountain, in a canyon, or on the edge of a grassland where groundwater bubbles to the surface. Often, a cienega does not drain into a stream, but evaporates, forming a small playa.

That is exactly what we found, seeps and shallow groundwater in deeply incised washes. As most of the water does evaporate, accumulated salt (we found water at twice the salinity of ocean water) prevents the growth of the emergent aquatic plants that is central to the modern definition of a “marsh.”

Topographic Map of San Sebastian Marsh at the confluence of San Felipe and Carrizo Creeks. The author of this map was generous in his representation of the verdancy of the site. Click to enlarge.

Then there are the preconceptions of terrain. In other regions of the West, Imperial and Coachella Valleys might have been a land of mesas and canyons, but here the collision of tectonic plates crushes the terrain, liberating a flood of gravels engulfing upturned sedimentary layers and thrusting up isolated mountain peaks. As you drive across the desert towards Arizona on I-8, I-10, or CA-78, mountains appear to pop up out of a sea of gravelly piedmont sparsely scattered with creosote bush and pockmarked with occasional stands of mesquite. It takes attention to notice that the piedmont is not flat, but dips and rolls across its component alluvial fans, ultimately sloping to the Salton Sea, 230-feet below sea level. Unless you are driving through a monsoon cloudburst, overpasses span dry washes or if wet, irrigation canals.

For those of us from temperate climes, rivers are often recognized by the swath of riparian vegetation snaking its way across the surrounding terrain. Recent research demonstrated (using a model with alfalfa sprouts!) that the riparian vegetation is a requisite component of a stream system that forms a classic meandering pattern upon the landscape. Due to the extended drought periods and saline soils, the washes are devoid of extensive riparian vegetation. This and the abundant gravel supply result in the streams having braided channels.

Nothing calls out that there are rivers here. Those east-west highways are situated along the strips of high ground. The low relief of the piedmont masks that here, like elsewhere, the landscape is a mosaic of watersheds. The highways are largely following the watershed divides. But for Anza, who was travelling north-south and in desperate need of water, understanding the watersheds was key. The strips of high ground on which we zip by were treacherous barriers to the expeditions, for they were certain to have no water and poor pasturage.

San Felipe Watershed. Blue lines are the creeks/arroyos; the red line outlines the watershed. Google Earth Image. Click to enlarge.

So, what is here and what did Anza encounter? Moving north from the Yuha Basin the expeditions spent a night on Coyote Wash, then the rest of Anza’s desert journey was within the vast San Felipe watershed. It runs approximately 60-miles north-south from Toro Peak to Superstition Mountain, and covers about 1,500 square miles. It includes the Borrego, Carrizo, and Terwilliger Valleys. The heart of the system is known as San Sebastian Marsh where dozens of creeks come together before flowing on to the Salton Sea near Kane Springs.

Once jaguar habitat, San Sebastian Marsh still supports a vast array of wildlife. A Desert Managers Group document states:

Besides their overall importance to wildlife, these riparian habitats and cienegas are critical to the survival of many rare, threatened, or endangered species recognized by the State and Federal governments. These include: desert pupfish, Peninsular bighorn sheep, least Bell’s vireo, yellowbilled cuckoo, Southwestern willow flycatcher, unarmored three-spined stickleback, black rail, and arroyo toad. Additionally, there are many species of special concern that inhabit these areas, including: yellow-breasted chat, yellow warbler, loggerhead shrike, Vaux’s swift, summer tanager, lowland leopard frog, California red-legged frog, Orcutt’s aster, and others.

Coming Next time: What we found in San Sebastian Marsh