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A ciénega (also spelled ciénaga) is a wetland system unique to the American Southwest and Northern Mexico. Ciénagas are alkaline, freshwater, spongy, wet meadows with shallow-gradient, permanently saturated soils in otherwise arid landscapes that often occupy nearly the entire widths of valley bottoms. That description satisfies historic, pre-damaged ciénagas, although few can be described that way now. Incised ciénagas are common today. Ciénagas are usually associated with seeps or springs, found in canyon headwaters or along margins of streams. Ciénagas often occur because the geomorphology forces water to the surface, over large areas, not merely through a single pool or channel. In a healthy ciénaga, water slowly migrates through long, wide-scale mats of thick, sponge-like wetland sod. Ciénaga soils are squishy, permanently saturated, highly organic, black in color or anaerobic. Highly adapted sedges, rushes and reeds are the dominant plants, with succession plants—Goodding's willow, Fremont cottonwoods and scattered Arizona walnuts—found on drier margins, down-valley in healthy ciénagas where water goes underground or along the banks of incised ciénagas.

Ciénagas are not considered true swamps due to their lack of trees, which will drown in historic ciénagas. However, trees do grow in many damaged or drained ciénagas, making the distinction less clear.

Current state

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The distribution and conservation status of ciénegas of Arizona and adjacent New Mexico were first inventoried and assessed systematically in 1985. Characterized by slow-moving, broad flows through extensive emergent vegetation, intact ciénegas were then rare, but reviews of historic accounts of the surface waters and landscapes of that region indicated they were previously extensive. Broadscale incision of ciénegas and conversion of large segments of former ciénegas to ephemeral surface flows through deeply incised former ciénega-formed soils, was hypothesized to have occurred predominantly in the late 1800s as a result of overgrazing, water diversions, and changing climates. More recent updates and geographically broadened inventories and status assessments of ciénegas now extend throughout Arizona and New Mexico eastward into Texas and south into Chihuahua and Sonora (México). Though often diverse local factors have clearly played major roles in altering some former ciénegas, the hypothesis of ongoing region-wide erosion since arrival of Europeans, and subsequent alteration of the land and aquifers (including more recent pumping of them), has been generally supported. "Since the late 1800s, natural wetlands in arid and semi-arid desert grasslands of the American Southwest and Northern Mexico have largely disappeared.". Historic ciénegas are now deeply entrenched and generally dry, or left with far less-permanent, often now ephemeral water. Broad grasslands adjacent to former ciénegas, once supported by shallow and stable groundwater maintained by ciénegas, are gone, replaced largely by mesquite and other arid-land vegetation, sometimes with narrow, remnant ciénegas persisting in deeply incised channels. Additional resources about ciénegas are available, including an extensive bibliography of relevant literature.

• Ciénagas in Progressive States from Healthy to Dead
• San Solomon Spring-fed ciénega, near Balmorhea, is in arid West Texas. The springs have a tremendous flow of 22 to 28 million gallons a day. (2009)
• Cloverdale Ciénega in the Bootheel area of southwest New Mexico. This illustrates what an undamaged ciénaga looks like under normal conditions: marsh-like, broad, shallow, slow-migrating water through thick vegetation. (2008)
• Cienequita, Las Ciénegas, southeast of Tucson, Arizona. With very little incising, this is a smaller, functioning ciénaga. (2012)
• Canelo Hills, Arizona. This is what a healthy ciénaga looks like after a flood, erosion is avoided by plants that lie down and spring back after heavy flows. (2009)
• Burro Ciénaga on the Pitchfork Ranch south of Silver City, New Mexico. Today, many of the few remaining ciénagas that still have water look like this, deeply incised by fast-flowing water trapped between vertical walls. (2005)
• Burro Ciénaga (2006) down channel about a quarter mile from the previous photograph. This section is shown more severely incised and creek-like: narrow rather than wide enough to cover the entire valley floor, but historically reaching the toes of the canyon on both sides. This ciénega has since been laboriously restored.
• Former San Simon Ciénega on the Arizona/New Mexico Border. Now dead, this ciénaga is beyond any possible recovery due to a serious water overdraft, despite a determined, long-term government effort. (2010)

Properties

Ciénegas occur at intermediate elevations (1000–2000 m) and are characterized by saturated, reducing soils with reliable water supply via seepage. Sedges, rushes, and grasses are the dominant plants, with a few trees that can withstand saturated soils, such as willows. Ciénegas trap organic matter from their surroundings, and are thus highly productive ecosystems.

The structure of a natural ciénega is influenced by long-term climatic cycles of wet and dry periods. During dry periods, falling water tables lead to a reduction in vegetation. Prolonged wet periods lead to increased vegetation and trapping of sediment, while brief periods of high rainfall may lead to carving of gullies. Runaway gully growth, as can occur when vegetation is artificially removed (e.g., by overgrazing), can lead to channelization and loss of the ciénega.

Importance and conservation

As a primary source of water in arid environments, ciénegas support a broad range of terrestrial life, including numerous endangered species. For instance, in Arizona, 19% of threatened, endangered, or candidate threatened or endangered species are directly associated with ciénegas. Ciénegas also purify surface water and mitigate flooding when heavy precipitation occurs, and help to cycle nutrients between water and soil. Humans have also long relied on the water provided by ciénegas: Indigenous Americans used ciénegas for water and hunting grounds, and a majority of pre-historic agricultural settlements occurred in the vicinity of ciénegas. Indigenous inhabitants of the American Southwest also gave spiritual significance to ciénegas and local watering holes.

The decline of ciénegas has been caused largely by changes in land use, primarily overgrazing (which removes water-absorbing vegetation) and overexploitation of ground water for agriculture and urban use. Direct removal of vegetation from the vicinity of wetlands has also been a cause of ciénega loss, as has the extirpation of beaver from the region. Preservation of existing ciénegas, and restoration of degraded ciénegas, depends on reversing these trends in land use and preventing their recurrence in the vicinity of ciénegas. This preservation is complicated by the fact that a majority of ciénegas are found on privately-owned land, most of which do not have binding conservation agreements or easements in place.

Occurrence

It is likely that there were many hundreds of long lost ciénagas, although there are only 155 identified or named ciénagas since the European arrival in the entire International Four Corners Region of the Southwest — that is, Arizona and New Mexico in the United States and Chihuahua and Sonora in Mexico. The tables below (with minor updates from ) summarize current knowledge of the distribution and status of ciénegas in the indicated U.S. and Mexican states.

In late 2018, as part of his effort to create a wetland action plan for the state of New Mexico, retired former New Mexico botanist Robert Sivinski discovered via satellite an additional 119 small ciénagas in New Mexico. This surprising number of previously unidentified or unstudied ciénagas suggests there may be more to be found. Further site-specific status assessment information and general information about ciénegas may be found in an open bibliography of ciénega literature.

See also

• La Cienega – census-designated place in Santa Fe County, New Mexico, United StatesPages displaying wikidata descriptions as a fallback
• Dry lake – Area that contained a standing surface water body
• Salt pan (geology) – Flat expanse of ground covered with salt and other minerals
• Oasis – Fertile area in a desert environment
• Grass valley – Meadow within a forested and relatively small drainage basin

References

1. ^ Hendrickson, Dean A.; Minckley, W. L. (1985). "Ciénegas - Vanishing Climax Communities of the American Southwest". doi:10.26153/tsw/9234. {{cite journal}}: Cite journal requires |journal= (help)
2. Hendrickson, Dean A; Minckley, Thomas A; Middleton, Barry R; Norman, Laura M (2021), "Ecology, Geography, Hydrology, Water Resources", Database of Cienega Locations in Southwestern United States and Northern Mexico, U.S. Geological Survey, doi:10.5066/p91fm1k1, retrieved 2023-01-29
3. Middleton, Barry R.; Norman, Laura M.; Hendrickson, Dean A.; Minckley, Thomas A. (2022). "Ecology, Geography, Hydrology, Land Use Change". Spatial Database of Known and Potential Ciénegas in the Greater Madrean Archipelago Ecoregion - ScienceBase-Catalog. U.S. Geological Survey. doi:10.5066/p9wgnzfg.
4. ^ Svinski, Robert C. (2018). "Wetlands Action Plan, Arid-land Spring Ciénegas of New Mexico" (PDF). New Mexico Ciénegas Action Plan. Retrieved January 29, 2023.
5. ^ Cole, A. T.; Cole, Cinda (August 2015). "An Overview of Aridland Ciénagas, With Proposals for Their Classification, Restoration and Preservation". {{cite journal}}: Cite journal requires |journal= (help)
6. ^ Minckley, T.A.; Turner, D.S. (2013). "The relevance of wetland conservation in arid regions: A re-examination of vanishing communities in the American Southwest". Journal of Arid Environments. 88: 213–221. Bibcode:2013JArEn..88..213M. doi:10.1016/j.jaridenv.2012.09.001.
7. Minckley and Brunelle (2007). "Paleohydrology and Growth of a Desert Ciénega". Journal of Arid Environments. 69 (3): 420–431. Bibcode:2007JArEn..69..420M. doi:10.1016/j.jaridenv.2006.10.014.
8. Hendrickson, Dean A. (January 29, 2023). "Ciénegas | Hendrickson Lab". Hendrickson Lab. Retrieved January 29, 2023.
9. ^ Hendrickson1;Minckley2;Contreras-Arquieta3, Dean A.1;Thomas A.2;Arturo3 (April 18, 2016). "North American Cienegas bibliographic database". Zotero Groups. Retrieved January 29, 2023.{{cite web}}: CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)
10. U.S. Bureau of Land Management (January 29, 2023). "Las Cienegas National Conservation Area". U.S. Department Of The Interior | Bureau of Land Management. Retrieved January 29, 2023.
11. Dec. 21, Avery McGaha; Now, 2015 From the print edition Like Tweet Email Print Subscribe Donate (2015-12-21). "The story behind a saved cienega in New Mexico". www.hcn.org. Retrieved 2023-01-30. {{cite web}}: |first2= has generic name (help)CS1 maint: numeric names: authors list (link)
12. Anonymous (2017). "Bringing the Water Back | The Pitchfork Ranch". New Mexico Land Conservancy print newsletter. Retrieved January 29, 2023.
13. Lisenby, P.E.; Tooth, S.; Ralph, T.J. (2019). "Product vs. process? The role of geomorphology in wetland characterization" (PDF). Science of the Total Environment. 663: 980–991. Bibcode:2019ScTEn.663..980L. doi:10.1016/j.scitotenv.2019.01.399. PMID 30739866. S2CID 73421044.
14. Bahre, Conrad Joseph (1991). A Legacy of Change: Historic Human Impact on Vegetation of the Arizona Borderlands. Tucson: University of Arizona Press.
15. Childs, Craig (2001). The Secret Knowledge of Water, Discovering the Essence of the American Desert. New York, Boston, London: Back Bay Books.
16. Hendrickson, D.A.; Kubly, D.M. (1984). "Desert waters: Past, present, and future". The Nature Conservancy News. 34: 6–12.
17. McNamee, Gregory (1994). Gila, The Life and Death of an American River. New York: Orian Books.

• Topography
• Wetlands
• Springs (hydrology)