go to chapters:
1. Overview
2. Study Area Description
3. Geomorphology and Sediment Cones
4. Environmental Resources
5.Problems and Opportunities
6. Recommendations
7. References
8. Appendices

4.0 Environmental Resources
Forgotten River Reach of the Rio Grande – Fort Quitman to Rio Conchos Confluence
4.1 Existing Ecological Conditions  July 2007
4.2 Water Quality
4.3 Groundwater
4.4 Vegetation
4.5 Wetlands
4.6 Wildlife
       4.6.1 Fish
       4.6.2 Mollusks and Crustaceans
       4.6.3 Endangered species

4.1 Existing Ecological Conditions  July 2007

The Rio Grande (or Rio Bravo as it is known in Mexico) throughout its course has been declared an Endangered River four times since 1993 by American Rivers, a national non-profit conservation organization.  More recently (2007), the Rio Grande was listed as one of the most endangered rivers globally, by the World Wildlife Fund. The Forgotten River Reach of the Rio Grande, the subject of this report, is a term first coined by Steve Harris of Rio Grande Restoration, a non-profit entity.  The term refers to an approximately 200 mile reach of the Rio Grande/Rio Bravo from El Paso to Presidio, Texas/Ojinaga, Mexico, where the river is now devoid of large, high energy spring runoffs due to the highly regulated Rio Grande Bureau of Reclamation Irrigation Project.

The study area is contained within a 1.86 mile buffer extending on either side from the main channel centerline of the Forgotten River Reach of the Rio Grande from Fort Quitman to Presidio, Texas. Areas within the buffer zone determined to exceed the river channel base elevation level by 30.28 feet or more were eliminated from the study area.

The University of Texas Center for Space Research (UTCSR) conducted a geospatial map compilation with available data during 2006-2007. Conclusions from these data are made throughout this document and a summary of their geospatial findings is presented in appendix A:

•  National Wetland Inventory maps of the project reach
•  Impaired stream segments from TCEQ 303(d) list (This list describes the status of the state’s waters, as required by           Sections 305(b) and 303(d) of the federal Clean Water Act. It summarizes the status of the state’s surface waters, including concerns for public health, fitness for use by aquatic species and other wildlife, and specific pollutants and their possible sources.)
•  Arroyo Confluences that exhibit sediment plugs, as visual inspection of one and two meter aerial imagery acquired during the mid 1990s, 2004, and 2005.
•  Pumping sites and Diversion Dams from USGS topographic maps and IBWC data.
•  Groundwater depth monitoring wells from the Texas Water Development Board Ground database reports.
•  Land ownership data from the original Texas Land Survey and Railroad Commission of Texas.
•  Vegetation mapping from 2002 LandSat 7 Enhanced Thematic Mapper Plus.
•  Structures and channelization infrastructure from IBWC datasets.
•  NRCS STATSGO soils from the USDA NRCS State Soil Geographic (STATSGO) database for Texas.
  

4.2 Water Quality                                              (return to table of contents)

The study reach is in Texas Water Quality Segment 2307 (TCEQ Basin 23, Segment 07).  Water quality measurements taken from 1970-76 reflect the flows at Fort Quitmanto be high in total dissolved solids, sodium and chlorides, which reflect drainage and return flows from irrigated areas.  Portions of the water passing the Fort Quitmanstation are evaporated and transpired and are replaced in part with fresher flows from arroyos which have dissolved solids on the order of 500-700 mg/l (IBWC 1978). Thus, concentrations at Upper Presidio are less than that at feet Quitman. (Miyamoto et al, 1995) examined the flow weighted annual salinity of the river from 1969 through 1989. An estimated 403,000 metric tons of salt entered the Forgotten River Reach at Fort Quitmanannually over this 20 year period. Other data collected by the Texas Clean Rivers Program indicate that concentrations of chlorides, total dissolved solids (TDS), and sulfates generally decrease in salt content as the Rio Grande courses from Fort Quitman to Presidio (Landis 2001)

Below is the most recent draft TCEQ 2004 303(d) Federal Clean Water Act list of impaired streams in the project study reach. The entire Forgotten River Reach of the Rio Grande from Fort Quitman to Presidio is classified as an impaired stream for one parameter or another.

Table 2 - Impaired Status, TCEQ Segment ID 2307, Rio Grande below Riverside Diversion Dam to the convergence with the Rio Conchos:

Key:
Category 5: The water body does not meet applicable water quality standards or is threatened for one or more designated uses by one or more pollutants.
Category 5b - A review of the water quality standards for this water body will be conducted before a Total Maximum Daily Load (TMDL) is scheduled.
Category 5c - Additional data and information will be collected before a TMDL is scheduled.
Rank: For water bodies in Category 5b, a ranking of "S" has been assigned to indicate that a standards review will be conducted before a TMDL is scheduled. For water bodies in Category 5c, a ranking of "D" has been assigned to indicate that additional data and information will be collected before a TMDL is scheduled. For Categories 5b and 5c, TCEQ will develop a separate prioritized schedule for standards review or the collection of additional data and information. These activities will be conducted at the same time that TMDLs are being developed for the parameters in Category 5a.  The Surface Water Quality Standards Advisory Work Group (SWQSAWG), EPA, and TCEQ are considering comments received during the comment period that ended March 1, 2006 on revisions to current Texas surface water quality standards. The next SWQSAWG meeting is scheduled for September 6, 2007, in Austin. More information can be found at http://www.tceq.state.tx.us/permitting/water_quality/stakeholders/swqsawg.html

The photograph taken below at the confluence of the Rio Conchos and the Rio Grande near Haciendita, Texas, above Presidio visually depicts the water quality issues in the Rio Grande, where the difference in the water clarity is visible as the rivers merge.
                                                                                            (return to table of contents)

4.3 Groundwater

Groundwater along the study area occurs in alluvial deposits. Recharge to the alluvial deposits in the valley occurs from seepage of the Rio Grande, from surface water applied for irrigation, and by subsurface discharge of the bolsons to the valley alluvium. The discharges from groundwater in the valley alluvium occur as flows into the Rio Grande, as evapotranspiration by trees, shrubs and other vegetation, and, to a slight extent, by pumping of wells for irrigation. A few wells in the valleys, near the northerly Presidio County line, have yields up to 2,100 gallons per minute (gpm). Yields of other existing irrigation wells range from 300 to 1200 gpm. The volume and quality of water from these wells vary greatly (IBWC 1978).

Water levels in the valleys are shallow, normally varying from the land surface to a depth of about 15 feet.  There is a direct relationship between the river stage and the groundwater adjacent to the river channel. During periods of high flow or flooding, the groundwater levels rise and approach the land level and exceed the land level in some cases where the river channel bottom elevation is about the same or above that of the adjacent land. During dry periods with little or no flow in the river, drainage and evapotranspiration lower water levels by about 5 feet  Cross sections taken across the floodplain and river channel show that in some locations the channel bottom is perched at a higher elevation than the adjacent lands. This perching results in sustained water logging of the surface soils.

Movement of groundwater is downstream along the course of the river. Generally, the hydraulic gradient is very flat, restricting movement of the groundwater.  Irregularly deposited clays, silts and fine sands impose further restrictions upon the movement of groundwater down gradient. This combination of poor movement of groundwater and evaporation and transpiration results in concentration of salt in the soil. In the immediate vicinity of the channel and adjacent floodplain, salinity ranges from 3,000 to 16,200 milligrams per liter (mg/l) total dissolved solids. Generally, nearer the margins of the floodplain, the salinity is less, ranging from 1500 to 3,000 mg/l total dissolved solids. In alluvial wash fan and floodplain deposits at the mouths of major canyons and arroyos, total dissolved solids usually range from 500 to 2000 mg/l. Local exceptions to these general condition are not uncommon (IBWC 1978).

Currently, based on data compiled by UTCSR (2006), there are 121 groundwater monitoring wells in the project reach.  Each well has an assigned Texas Water Development Board well number and each is individually owned.  Records of changes in groundwater levels relative to surface elevations at these wells can be found at TWDB’s website http://www.twdb.state.tx.us/publications/reports/GroundWaterReports/GWDatabaseReports/GWdatabaserpt.htm

                                                                                                          (return to table of contents)
4.4 Vegetation

William Whiting led a stage coach route survey up the Rio Grande to El Paso, Texas, in 1849. His journal contains descriptions of large groves of cottonwoods, willows, mesquites, and extensive areas of grass along the Rio Grande floodplain. Animals specifically mentioned were white pelicans and mule deer. (Bieber 1937)  In 1859, Emory reported heavy growths of cottonwood and willow intermixed with mesquite and seep willow along what is now the study area.

Because of the spatial and temporal variability built into the geomorphic processes of channel meandering, channel narrowing, and flood deposition and the plant reproduction dependent upon them, a continuous ribbon of cottonwoods and willows did not likely occur along the Forgotten River Reach (Stotz et al. 2000). Rather, patchy distributions were common in early accounts, with occasional untimbered stretches. Grasses such as sacaton and phragmites and possibly vine mesquite were noted by some travelers of the Rio Grande, and Fosberg (1940) documented many wetland plants of the Mesilla Valley, including duckweed (Lemma minor) and pondweed (Potamogeton spp.), as well as emergents like cattails (Typha angustifolia), rushes (Juncus balticus), a variety of sedges (Cyperus, Eleocharis, and Scirpus spp.) and horsetails (Equisetum hyemale).

 Travelers and settlers likely played a role in a significant change in the vegetation along the river by introducing exotic plants. In 1930, Fosberg (1940:581) collected 23 species of introduced plants in the Mesilla Valley north of the study area. The more common exotic species were tamarisk or salt cedar, Russian thistle (Salsola kali), thistles (Sonchus spp.) and an introduced reed (Arundo donax) (Stotz et al. 2000). The most impacting of these was salt cedar, a phreatophyte (a groundwater seeking invasive plant) introduced as an ornamental and for erosion control. In small numbers, it was present in the Albuquerque area in 1908.  It was planted along the banks of the Rio Puerco, a tributary of the Rio Grande, by the Middle  Rio Grande Conservancy District in 1926 and occurred in the Presidio Valley by 1935 (Everitt 1998). As dam building, flow regulation, and channelization occurred, tamarisk became more and more dominant; Everitt (1998) argues that tamarisk was not responsible for changes in river hydrology (such as channel width or flood stage), but that it simply responded to such changes that were already underway. In both the Middle Rio Grande and Presidio valleys, extensive spreading of tamarisk occurred after significant flood events in 1929 and 1942, respectively (Crawford 1993; Everitt 1998). As Everitt explains, such floods dispersed tamarisk seeds widely across the floodplain to areas previously not colonized and also opened new habitats via scouring and channel migration.

Everitt (1998) concluded that there is no evidence that tamarisk actively displaced native species along the Rio Grande in the El Paso and Presidio valleys. However, in some areas, its prodigious production of airborne seeds, long seed production and germination periods, and rapid growth allowed it to compete favorably with native trees in colonizing newly stabilized sandy or silty surfaces (Graf 1994). Regardless of whether tamarisk has played an active role in replacing native vegetation, it has come to dominate many areas along the Rio Grande. From Fort Quitmanthrough the Presidio Valley, tamarisk now occupies some patches of land once covered by cottonwood woodland and tornillo thickets.  Ohmart (2002, as referenced in Fullerton and Batts 2003) estimated that only about 60 acres of cottonwood-willow remain below El Paso, with soil salinity being a limiting factor that has affected species composition. 

Salt cedar was not in abundance or considered a dominant species in riparian habitats along the Rio Grande until about or shortly after 1942. The spill from Elephant Butte Reservoir in 1942 which inundated the floodplain appears to have scattered seeds and formed optimum germination conditions for salt cedar.

Upstream reservoirs have regulated and reduced downstream flows, which in turn, have enabled encroachment of salt cedars into the river channel. The afore-described deteriorated channel conditions, and the resultant overflows and ponding of highly saline waters, evaporate and leave the soil encrusted with salt accumulations which reduce soil productivity. Most native species cannot tolerate these high salt conditions, but salt cedar thrives in these conditions. Impoundments, fires and salt accumulations have aided the spread and dominance of salt cedar within the study area at the expense of native species (Ohmart et al. 1977).

The floodplain within the study area on the U.S. side had a total area of 18,100 acres in 1977. Of this, approximately 60 acres were in cottonwood and willow.

 To define the expansion of the denser vegetation areas, principally salt cedar, such areas were delineated on 1947, 1967, and 1974 aerial photographs. The results listed in the Table 3 show that salt cedar area doubled between 1947 and 1974, and at that point salt cedar occupied about 46% of the entire floodplain.  The data also illustrates the progress of salt cedar encroachment in the study reach from 1947-74.                                                                        (return to table of contents)

Figure 15 - Large old-growth salt cedar trees on the Green River Valley Ranch, exceeding 20" Diameter Breast Height; February 2007.

Year	United States	Mexico	Total
1947	5,800	4,600	10,400
1967	8,700	4,900	13,600
1974	12,900	7,300	20,200

Table 3 - Salt Cedar Occupied Area (acres) in floodplain, Fort Quitman to Haciendita, Texas (IBWC 1978)

Engel-Wilson and Ohmart (1978) classified plant communities along the Forgotten River Reach into four dominant community types: 1) salt cedar; a community dominated by dense stands of salt cedar with little or no understory except for small patches of grass and seep willow where the salt cedar canopy was not continuous.  2) cottonwood-willow with substantial salt cedar but contain enough cottonwoods and southwestern black willows to have considerable impact on wildlife habitat; 3) screwbean mesquite-wolfberry community with screwbean mesquite, honey mesquite and wolfberry as the dominant plants, a rare community type found on the floodplain outside of the band of salt cedars which occurred along the river, characterized by screwbean mesquite trees scattered through a shrubby understory of Torrey wolfberry and honey mesquite, and 4) thorny shrub, which is a complex mixture of a variety of desert shrubs. They also classified structural type, based on distribution and density of foliage at various heights above ground level. Type I vegetation has trees over 30 feet tall with the foliage distributed somewhat evenly among the layers. This type is rare in the study area. Type II, which captures most of the salt cedar, is characterized by trees up to 30 feet tall and virtually no green vegetation above five feet and 80% of the foliage is at 10 feet or more. Type III vegetation is composed of trees mostly 10 to 20 feet with most of the foliage concentrated below 15 feet, including a well-developed bottom layer. Type IV vegetation has some trees 15 feet and above, but most of the foliage is below 10 feet with the greatest amount in the lower levels. Type V has few trees over 10 feet but most of the foliage is below five feet. Type VI is the shortest structural type. Most of the foliage is in the shrub and forb/grass levels below five feet, sometimes with an occasional tree over 10 feet tall. Most of the thorny shrub in the study area is Type VI.  Table 4 illustrates vegetation types present in the study area in 1977.  Appendix C catalogs the plant species found by Engel-Wilson and Ohmart in 1977.

Table 4 - Areas of vegetation types on the U.S. side, study area, Forgotten River Reach, Rio Grande, Fort Quitman to Rio Conchos Confluence, 1977.                                                          (return to table of contents)

Overgrazing by domestic livestock has resulted in a shift from primary grasses to sparse woody shrubs and annual grasses. This existing vegetation does little to slow surface waters during torrential rains, and, consequently, large sediment loads are transported into the study reach to compound the problem of river channel changes. Species that were likely present include: mesa dropseed, sand dropseed, saltgrass, sacaton, sideoats grama, six weeks grama, black grama, blue grama, cowpen daisy, desert baileya, desert seep weed, dock, grounsel, jimmyweed, mountain pepperweed, rocket mustard, sand verbena, spectacle fruit, tansy mustard, tree tobacco, trailing allionia and wild buckwheat.

Based on LandSat 7 Enhanced Thematic Mapper Plus data collected in 2002, the following acreages (Table 5) of vegetation types occur as estimated by UTCSR from their compiled geospatial database.  Since the location of the channel and thus the boundary are often un-detectable (for the reasons stated above) from satellite imagery, the acreage given is for both the Mexican and U.S. sides, within 1.86 miles of the channel unless an elevation rise of 32.8 feet or more was encountered.  High or moderate probability salt cedar monoculture or mixed stands totaled 37,761 acres on both sides. 

Table 5 - Acreage of vegetation types within the study area as photo interpreted by UTCSR from 2002 LandSat data

An indication of the difficulty of maintaining restoration plantings without an investment in periodic inspection and maintenance is given by the current status of the Cecil’s Pond revegetation project of 1985.  This revegetation effort was undertaken to partially mitigate for wildlife habitat losses incurred in construction and clearing activities on the Boundary Preservation Project of 1980 (Anderson and Ohmart 1986). A visit to the site by a Corps biologist and a Corps contractor on February 16, 2007, revealed poor survival of cottonwood and black willow plantings. Uncontrolled livestock grazing, drought, and channel incision and entrenchment appeared to be the main causes of planting failures observed, as less than 20 willows and 10 cottonwoods were found to have survived on the 12 acre site, despite a planting effort of over 1,000 trees in 1985. Salinity of soil and surface and groundwater may have also contributed to the demise of plants.

Figure 16 - The Rio Grande near Cecil's Pond Mitigation site - entrenched and displaying poor water quality, upstream of Haciendita, Texas looking downstream

Figure 17 - A Corps' contractor examines the few remnants of over a thousand Cottonwoods and Willows that were planted in 1985 at Cecil's Pond Mitigation Site - Note the artificial snag placed in 1985 and still standing on the far left.  (2007)   (return to table of contents)

Currently, some ranchers mow salt cedar saplings and seedlings in their Bermuda grass pastures in the spring when/if soils have dried out from the previous monsoon. Old tire casings are put over farm tractor tires to protect the tractor tires from being impaled and flattened by salt cedar sprouts and stubs. This mowing process tends to encourage further sprouting of salt cedar saplings, but allows the Bermuda grass a somewhat competitive advantage. Few if any ranchers follow up this treatment with either foliar or basal stem herbicide treatment.  Hudspeth County Soil and Water Conservation District has offered the Chinese leaf beetle (Diorhabda elongate) to Lester Talley, the private landowner of Rancho Consuelo.   Likewise, a major effort to introduce leaf beetles above Candelaria was being discussed locally in January 2007.  (Ty Fain, Jack DeLoach, et al. had recently met with local ranchers and farmers and state and Federal agencies.  It is possible that this project could change the density of live stems of both old and young stands.  It is questionable whether any geomorphic benefit would accrue in the salt-cedar armored sections without removal of dead boles and roots.)

Figure 18 - A Bermuda grass pasture being colonized with Salt cedar in southern Hudspeth County, Texas  (January 2007)

4.5 Wetlands

IBWC (1978) estimated 1,764 acres of inland saline flats that were wetlands on the U.S. side, ninety three percent of which were occasionally flooded agricultural fields and salt cedar and mesquite covered flats. A few small wetlands were relatively permanent. There were two small cattail marshes, one, one-half mile downstream from Panales Arroyo near Ruidosa, and another, one-half mile southwest from Candelaria. Both are borrow pits which were formed during the construction of private levees.
Ephemeral ponding of water occurrs in the study area during wet years where the river is perched or where water is trapped behind old levees and prevents drainage of these ponded areas. High ambient temperatures and low relative humidities likely promoted rapid evaporation of the ephemeral ponds so that over the years these low areas become highly saline. Rooted aquatic vegetation never became established due to the ephemeral nature of surface water.

The UTCSR geospatial database calculated, based on National Wetland Inventory Maps (May 1984), a sum of 14,266 acres of wetlands in the project area.  The “Palustrine scrub-shrub needle-leaved deciduous (PSS2J), intermittently flooded, which indicates tamarisk, occupies 6,205 acres, according to the UTCSR database.    (return to table of contents)

4.6 Wildlife

The spread of tamarisk may have had significant impacts on animal communities. Along the river above Presidio, Engel-Wilson and Ohmart (1978) found that the distributions of many different groups of vertebrates were affected by the presence of tamarisk. In their study of the project reach in 1978, they found that Cottonwood-willow Type I had the greatest density of birds, but Thorny Shrub VI had the greatest diversity. Cottonwood-willow and screwbean mesquite-wolfberry were preferred by twice as many bird species as any other community during the summer breeding and nesting season. Salt cedar had a fairly high bird density during the summer, but this was primarily due to the large number of nesting white winged doves (Zenaida asiatica). Yellow breasted chats (Ictera virens), various hummingbird species, and summer tanagers (Piranga rubra)also used salt cedar. The screwbean mesquite-wolfberry community had high bird densities and a fairly high diversity. Gambel’s quail (Callipepla gambelii)was found primarily in cottonwood willow communities in the floodplain. Mule deer (Odocoileus hemionus)and peccaries (Tayassu tajacu)rarely entered salt cedar or cottonwood-willow except to obtain water from the river. Beavers (Castor Canadensis) were noted to be dependent upon cottonwood-willow for food and dam-building materials, although some salt cedar was used in at least one of the three dams located in the study area. White-footed mice (Peromyscus spp.) were the most frequently found rodent in salt cedar, but the lowest rodent densities overall occurred in salt cedar and thorny shrub. House mice (Mus musculus), hispid cotton rats (Sigmodon hispidus), and western harvest mice (Reithrodontomys megalotis), deer mice (Peromyscus maniculatus), cactus mice (Peromyscus eremicus), and white-footed mice (Peromyscus spp.) were found in the moister, riparian cottonwood-willow community. Texas toads (Bufo speciosus) were the most common toad found on the floodplain, although red-spotted toads (Bufo punctatus), Great Plains narrow-mouthed toads (Gastrophryne olivacea) and Couch’s spadefoots (Scaphiopus couchii)also occurred. Reptiles were most abundantly found in thorny shrub VI, and almost no reptiles occurred in salt cedar; however, it was observed that reptiles will move into a salt cedar area if the canopy is open and grassy openings are present.

Appendix C lists the faunal species within the study area as recorded during Ohmart et al.’s reconnaissance study of 1992 (Ohmart et al 1993).     (return to table of contents)

4.6.1 Ichthyofauna

Twelve species of fish representing eight families were identified by Engel-Wilson and Ohmart (1978) from samples taken at 20 locations throughout the study area and in the channelized portions above and below the study area. Five species (red shiner [Notropis lutrensis], common carp [Cyprinus carpio], gizzard shad [Dorosoma cepedianum], mosquito fish [Gambusia affinis], and green sunfish [Lepomis cyanellus]) constituted 96% of the sampled population, with the red shiner comprising 49% of the total. The five species of game fish (channel catfish [Ictalurus punctatus], blue catfish [Ictalurus furcatus], green sunfish, longear sunfish [Lepomis megalotis], and white bass [Morone chrysops]) comprised 11% of the population. Bullhead minnow (Pimephales vigilax), river carpsucker (Carpiodes carpio) and yellow bullhead (Ictalurus natalis) and speckled chub (Macrhybopsis aestivalis) were also found in the project study reach by Bestgen and Platania (1988). Fish density in the Rio Grande above the Rio Conchos was found to be 283 per 328 square feet. Salinity and conductivity values were found to rise dramatically downstream of Acala and feet Hancock in Hudspeth County , upstream of feet Quitman, where most diverted water returned to the Rio Grande, carrying a large ambient load of dissolved solids (Bestgen and Platania 1988).

Two tributaries of the Rio Grande in the project area (Capote Creek, which is an intermittent spring fed freshwater stream, and Indian Hot Springs, where warm saline spring water drains into the river) were sampled extensively. Hubbs (1977) thought that these areas were likely to have endemic or rare fishes; however, he found no endemic or rare fishes at these sites or anywhere else in the study area.

4.6.2 Mollusks and Crustaceans

Metcalf (1978) identified ten species of aquatic snails, four species of bivalve mollusks, an aquatic crustacean, and one species of terrestrial crustacean in the river and in the contiguous floodplain of the study area. He also found nine xeric land snails, which are widespread throughout the southwestern United States and into northern Mexico. 
The diversity of aquatic invertebrates in the Rio Grande was low throughout the study reach (Metcalf, 1978). One two-mile stretch of river directly upstream from Haciendita, supported a rather diverse fauna, however. This stretch has relatively permanent water, as before stated, due to return flows from lands in Mexico irrigated with Rio Conchos water. The aquatic fauna here appears to be similar to that found in the area under presettlement conditions. Of the ten species of mollusks taken in this two-mile stretch, four species (Anodenta imbecillis, A. musculium transversum, A. antillorbis sonorensis, and A. micromenetus dilatatus) were found only in this reach. Only a few opportunistic species occur in the rest of the river such as Physa virgata and (in some places) Lymaaea bulimoides. Much of the channel was dry and contained no live aquatic invertebrates at all. No mollusks or crayfish were found in oxbow pools or intermittently flooded fields or flats. The springs in the valley contained a relatively diverse molluscan fauna including one specie (Lymnaea parva) which was found only in springs away from the river and is common elsewhere in the country.               (return to table of contents)

4.6.3 Federally or State Listed Species

The bald eagle (delisted June 2007) has been sighted over the study area during its migration, but it is not believed that this species utilizes the area to the extent that any work done under a construction alternative would adversely impact it.

Certain species possibly occurring within the habitats of the study reach are of particular concern to Federal and state officials due to pressures from human activities. Included among these species are the following (TPWD 2007):

Species Common Name	Scientific Name	Status	County
American peregrine falcon	Falco peregrinus anatum	SE	Hudspeth Presidio
Northern aplomado falcon	Falco femoralis septentrionalis	FE SE	Hudspeth Presidio
Common black-hawk	Buteogallus anthracinus	SE	Presidio
Gray hawk	Asturnina nitida	ST	Presidio
Southwestern willow  flycatcher	Empidonax traillii extimus	FE SE	Presidio
Western Yellow-billed cuckoo	Coccyzus americanus occidentalis	FC	Presidio Hudspeth
Zone-tailed hawk	Buteo albonotatus	ST	Presidio
Gray  wolf	Canis lupus	FE SE	Hudspeth Presidio
Greater long-nosed bat	Leptonycteris nivalis	FE SE	Presidio
Chihuahua shiner	Notropis Chihuahua	SE	Hudspeth
Bluntnose shiner	Notropis simus	ST	Hudspeth Presidio
Blue Sucker	Cycleptus elongates	ST	Presidio

Conchos pupfish	Cyprinodon eximius	ST	Presidio
Rio Grande silvery minnow	Hybognathus amarus	FE SE	Hudspeth Presidio
Mexican stoneroller	Campostoma ornatum	ST	Presidio
Chihuahuan Desert lyre snake	Trimorphodon vilkinsonii	ST	Hudspeth Presidio
Chihuahuan mud turtle	Kinosternon hirtipes murrayi	ST	Presidio

   FE=Federally Endangered     SE=State Endangered      ST=State Threatened       FC=Federal Candidate

(return to table of contents)