J.04_C.5_Biological_Resources_Survey_Aug_2005.pdf

United States Section International Boundary and Water Commission

Biological Resources Survey Rio Grande and Tijuana River Flood Control Projects New Mexico, Texas and California

August 2005

Final Report

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Contents

Section 1 Introduction

1.1 Background ...............................................................................................................1-1

1.2 Purpose and Objective .............................................................................................1-4

1.3 Agency Coordination...............................................................................................1-4

Section 2 Description of Project Areas

2.1 Rio Grande Watershed.............................................................................................2-1

2.2 Rio Grande Canalization Project ............................................................................2-4

2.2.1 Vegetation Communities..........................................................................2-4

2.2.2 Wildlife Communities...............................................................................2-5

2.2.3 Threats to Vegetation and Wildlife Communities ................................2-6

2.2.4 Threatened and Endangered Species .....................................................2-6

2.2.4.1 Federal .....................................................................................2-7

2.2.4.2 State..........................................................................................2-9

2.3 Rectification Project ................................................................................................2-10

2.3.1 Vegetation Communities........................................................................2-11

2.3.2 Wildlife Communities.............................................................................2-12

2.3.3 Threats to Vegetation and Wildlife Communities ..............................2-12

2.3.4 Endangered and Threatened Species ...................................................2-13

2.3.4.1 Federal ...................................................................................2-13

2.3.4.2 State........................................................................................2-14

2.4 Presidio Project ................................................................................................2-15

2.4.1 Vegetation Communities........................................................................2-16

2.4.2 Wildlife Communities.............................................................................2-16

2.4.3 Threats to Vegetation and Wildlife Communities ..............................2-17

2.4.4 Threatened and Endangered Species ...................................................2-18

2.4.4.1 Federal ..................................................................................2-18

2.4.4.2 State........................................................................................2-19

2.4.5 Biological Survey- June 2005..................................................................2-20

2.4.5.1 Aquatic Ecosystem Observation........................................2-21

2.4.5.2 Terrestrial Ecosystem Observations..................................2-23

2.4.5.3 Observed/Potential Threats to Biological Resources .....2-24

2.5 Lower Rio Grande Valley Flood Control Project ...............................................2-25

2.5.1 Vegetation Communities........................................................................2-26

2.5.2 Wildlife Communities.............................................................................2-27

2.5.3 Threats to Vegetation and Wildlife Communities ..............................2-29

2.5.4 Threatened and Endangered Species ...................................................2-29

2.5.4.1 Federal ...................................................................................2-29

2.5.4.2 State........................................................................................2-31

2.6 Tijuana River Flood Control Project ....................................................................2-34

Table of Contents Draft Biological Resources Survey

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2.6.1 Vegetation Communities........................................................................2-34

2.6.2 Wildlife Communities.............................................................................2-35

2.6.3 Threats to Vegetation and Wildlife Communities ..............................2-36

2.6.4 Threatened and Endangered Species ...................................................2-36

2.6.4.1 Federal ...................................................................................2-36

2.6.4.2 State........................................................................................2-38

2.7 Data Gaps and Plan to Address............................................................................2-39

Section 3 References

Appendix A Fish and Wildlife Agency Correspondence Appendix B

Item 1 Plant Species in the Canalization Project per USIBWC 2004 Biological Assessment Item 2 Avian Species Observed in the Canalization Project during 2004 USIBWC Field Surveys

Appendix C Bird Species Observed During 2005 Presidio Field Survey Appendix D Photograph Log from 2005 Presidio Field Survey

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Figures

Figure 1-1 Project Area Locations – Rio Grande.......................................................1-2 Figure 1-2 Tijuana River Flood Control Project Area ..............................................1-3

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Tables

Table 2-1 Federally Listed Species for Sierra, Dona Ana, and El Paso Counties ......................................................................................................2-8 Table 2-2 New Mexico State Listed Species for Rio Grande Watershed Caballo Dam through El Paso; and Texas State Listed Species for El Paso County.....................................................................................2-9 Table 2-3 Plants Typical Of Mesquite-Sandsage Shrub And Creosote Bush-

Lechuguilla Shrub...................................................................................2-11 Table 2-4 Federally Listed Species for El Paso and Hudspeth Counties ..........2-13 Table 2-5 Texas State Listed Species for El Paso and Hudspeth Counties .......2-14 Table 2-6 Plants Typical Of Mesquite-Saltcedar Brush/Woods And Creosote Bush-Lechuguilla Shrub.........................................................2-16 Table 2-7 Federally Listed Species for Presidio County......................................2-18 Table 2-8 Texas State Listed Species for Presidio County ..................................2-19 Table 2-9 Results of Aquatic Sampling / Habitat Scoring..................................2-22 Table 2-10 Plants Typical Of Mesquite-Blackbrush Brush And Mesquite-

Granjeno Parks ........................................................................................2-27 Table 2-11 Federally Listed Species for Hidalgo, Cameron, and Willacy Counties ....................................................................................................2-30 Table 2-12 Texas State Listed Species for Hidalgo, Cameron and Willacy

Counties....................................................................................................2-31 Table 2-13 Federally Listed Species for San Diego County ..................................2-37 Table 2-14 California State Listed Species Sighted in Imperial Beach USGS 7.5 Minute Quadrangle ...............................................................2-38

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Section 1 Introduction The United States Section of the International Boundary and Water Commission (USIBWC) maintains four flood control projects along the Rio Grande and one along the Tijuana River. The four Rio Grande flood control projects are located between Percha Dam in Sierra County, New Mexico, and the Gulf of Mexico. The Tijuana River flood control project is in the United States portion of the Tijuana River in San Diego County, California.

This biological resources survey is a literature review of biological resources such as habitats, communities, and species in the Rio Grande and Tijuana River watersheds, focusing on those resources within the five flood control project areas. A field biological survey of the Presidio-Ojinaga flood control project was conducted in June of 2005 to supplement and verify the information obtained through the literature review. The results of the literature review and field survey are documented in this report.

1.1 Background

The USIBWC maintains four flood control projects along the Rio Grande:

1) Canalization Project, extending 105.4 miles from Percha Diversion Dam in New Mexico to American Diversion Dam in El Paso County, Texas;

2) Rectification Project, extending 86 miles from American Diversion Dam to Fort Quitman, Texas;

3) Presidio-Ojinaga Flood Control Project, extending 15.2 miles along the Rio Grande and including spur levees between the sister cities of Presidio, Texas and Ojinaga, Chihuahua, Mexico; and

4) Lower Rio Grande Flood Control Project (LRGFCP), extending 180 miles between the town of Peñitas, Texas, to the Gulf of Mexico.

The major diversions within the lower region of the Rio Grande include the Percha Leasburg, Mesilla, American, International, and Riverside dams.

In addition, the USIBWC maintains the Tijuana River Flood Control Project, located in the United States portion of the Tijuana River, extending 2.3 miles from the international boundary. This project represents a continuation of the flood control project located in Mexico, and provides flood protection to areas of San Diego, California, in the United States.

Figure 1-1 shows the locations of the four Rio Grande flood control projects. Figure 1- 2 shows the location of the Tijuana River Flood Control Project.

A US-International Boundary Water Commission PEIS Project Area Locations - Rio Grande

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Lower Rio Grande Valley Flood Control Project

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Figure 1-1

Tijuana River Flood Control Project Area Figure 1-2A

Section 1 Biological Resources Survey

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1.2 Purpose and Objective

This document does not include any new field work in the Canalization, Rectification, Lower Rio Grande Valley, or Tijuana River project areas. It does include the results of a new field survey in the Presidio project area. Current lists of endangered, threatened, candidate, rare and special species according to the United States Fish and Wildlife Service and the New Mexico, Texas and California state agencies are also included in this document. General descriptions of vegetation and wildlife in the Rio Grande and Tijuana River watersheds are provided, including common plants and animals in the five flood control project areas. Sensitive plants and animals known or suspected to be in the study area according to previous reports are discussed.

1.3 Agency Coordination

Comments were sought for inclusion in this report from four United States Fish and Wildlife Service offices, as well as three state-level wildlife offices. The comments were used to add field-specific present knowledge of biological conditions in each of the project areas to this report. The letter soliciting comments, the list of agencies contacted, and the responses received from the agencies are included in Appendix A.

Responses were received from the Carlsbad and Albuquerque offices of the United States Fish and Wildlife Service and the State of New Mexico Department of Game and Fish.

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Section 2 Descriptions of Project Areas The major biological resources (i.e., habitats, communities, and species) associated with the five project areas are described in this section.

2.1 Rio Grande Watershed

The Rio Grande, at 1,896 miles in length, is the nation’s fifth longest river, originating in south central Colorado and flowing to the Gulf of Mexico. The Texas portion of the Rio Grande was designated as an American Heritage River in July of 1998. A segment of the river, about 1,250 miles in length, forms the boundary between the United States and Mexico. The Rio Grande and its tributaries, all of which are ephemeral, are drainages for the plateau shrub lands of New Mexico, the Chihuahuan Desert of New Mexico and Texas, and the Tamaulipan Mezquital of south Texas and adjacent Mexico. The USIBWC flood control projects in New Mexico and Texas are within the Chihuahuan Desert and Tamaulipan Mezquital regions.

The Chihuahuan Desert is considered the most biologically diverse desert in the world (Ricketts et al. 1999 in Gil and Wilkins 2004). Most of the Rio Grande watershed lies within the Chihuahuan Desert, as defined by Schmidt (1979) in Brown (1994). The Chihuahuan Desert can be generally characterized by dominant vegetative communities, including creosote bush (Larrea divaricata), tarbush (Flourensia cernua), whitethorn acacia (Acacia constricta), sandpaperbush (Mortonia scabrella), mesquite (Prosopis juliflora glandulosa), succulents (Agave, Yucca, Dasylirion, Opuntia), mixed shrubs, and saltbush (Suaeda torreyana), with ocotillo (Fouquieria splendens) also commonly present (Brown 1994).

The riparian habitat consists mainly of tall dense vegetation such as the cottonwood-willow and saltceder (Tamarix L), and short sparse vegetation such as thorny shrub communities and screwbean mesquite-wolfberry. The salt cedar tends to have an advantage over other species because of its adaptation to the saline soils. Screwbean mesquite-wolfberry occurs mainly in the flood plain, beyond the cottonwood/willow or saltcedar. Honey mesquite may also be present in this habitat along with quailbush (Atriplex lentiforms). Openings between shrubs may allow for the growth of forbs and grasses such as alkali sacaton (Sporobolus airoides) and saltgrass (Distichlis spicata). The thorny shrub community is composed of mesophylic plants such as honey mesquite and buckthorn (Rhamnus californica), and xerophylic species such as creosote bush and lechuguilla (Agave lecuguilla). Wet meadows, palustrine marshes, spring seeps, perched wetlands, salt marshes, and sand bars also occur throughout the river (Fullerton and Batts 2003).

Animals common to or characteristic of the Chihuahuan desert include a large variety of invertebrates and vertebrates. Mammals commonly associated with the Chihuahuan desert include several types of rodents and other small mammals, such as desert pocket gopher (Geomys atenarius), Nelson’s kangaroo rat (Dipodomys nelsoni), Nelson’s pocket mouse (Chaetodipus nelsoni), and desert-adapted forms of ground squirrels (Spermophilus sp.) , woodrats (Neotoma sp) cottontail (Sylvilagus sp.), and

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P:\9129-43926 (IBWC PEIS)\Biological Resources Survey\Second Draft\Section 2-Biological Resources Survey.doc larger mammals such as mule deer (Odocoileus hemionus) and bighorn sheep (Ovis Canadensis) (Brown 1994).

Bird communities are comprised of predominantly wide-ranging desert-adapted species, with only the scaled quail (Callipepla squamata) and white-necked raven (Corvus albicollis) considered characteristic of the Chihuahuan desert (Brown 1994).

Other common bird species found within the Chihuahuan desert (as well as within other arid ecosystems in the Southwest) include mourning dove (Zenaida macroura), roadrunner (Geococcyx californicus), lesser nighthawk (Chordeiles acutipennis), Scott’s oriole (Icterus parisorum), cactus wren (Campylorhynchus brunneicapillus), curve-billed thrasher (Toxostoma curvirostre), and black-throated sparrow (Amphispiza bilineata) (Brown 1994).

Reptiles are well-represented in the Chihuahuan desert, and commonly observed taxa include a wide variety of lizards, such as Texas banded gecko (Coleonyx brevis), horned lizards (Phrynosoma sp.), several species of spiny lizards (Sceloporus sp.), and whiptail lizards (Cnemidophorus sp.). The latter genus includes interesting parthenogenic taxa whose populations consist of all female clones; however, these are not restricted to the Chihuahuan desert. Snakes characteristic of (but not necessarily limited to) the Chihuahuan desert include trans-Pecos ratsnake (Bogertophis subocularis), western hooknose snake (Gyalopion canum), Texas black-headed snake (Tantilla atriceps), and several species of whipsnake (Masticophis sp.) and ratttlesnake (Crotalus sp.). The commonly encountered rattlesnakes include wide-ranging species that are found beyond the Chihuahuan desert, such as the Mojave rattlesnake (C.

scutulatus) and western diamondback ratttlesnake (C. atrox). Most of the other reptile species identified above are characteristic of the Chihuahuan desert, but even some of these are relict grassland species. Most of the lizards identified above are diurnal and commonly seen, but geckos and several of the snake species identified are nocturnal, especially during the hottest months.

In general, desert environments do not support abundant or diverse amphibian communities compared to wetter environments. However, several arid-adapted amphibians can be found in the Chihuahuan desert, and some of these can be abundant where habitats are suitable. Desert-adapted species that may be found within the Chihuahuan desert include tiger salamander (Ambystoma tigrinum), spadefoots (Scaphiopus sp. and Spea sp.), Great Plains narrowmouth toad (Gastrophryne olivacea), and several species of true toads (Bufo sp.). These are not necessarily commonly observed animals because they are often nocturnal and in some cases come to the surface only briefly during short breeding periods.

The Tamaulipan Mezquital of south Texas and adjacent Mexico is considered one of the “last great habitats” in North America due to its unique biological resources (Fulbright and Bryant 2002 in Gil and Wilkins 2004). This habitat is rapidly being lost in the United States due to urbanization and agricultural development along the Rio Grande in south Texas. Many of the vertebrates identified above for the Chihuahuan desert, or closely related taxa, may also occur in far south Texas where suitable habitats still exist. Also, a few species of vertebrates unique to this environment, such as Texas indigo snake (Drymarchon corais erebennus), can still be found in appropriate habitats but are becoming increasingly scarce.

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The United States Forest Service (USFS) takes a somewhat different approach to describing habitats of the United States by identifying ecoregions, the boundaries of which are slightly different than the boundaries of the Chihuahuan desert and Tamaulipan Mezquital described above. Each ecoregion represents a unique combination of vegetative communities and climatic conditions. Ecoregions consist of several divisions, including Domains, Divisions, Provinces, and in some cases Regimes. The entire 335,000 square mile Rio Grande watershed falls within the Dry Domain. Several Divisions, Provinces, and Regimes within this Domain have been identified by the USFS. These are described below.

Tropical/Subtropical Steppe Division

Colorado Plateau Semi-Desert Province in southern New Mexico

Southwest Plateau and Plains Dry Steppe and Shrub Province in central and southern Texas

Tropical/Subtropical Steppe Regime Mountains

Arizona-New Mexico Mountains Semi-Desert – Open Woodland – Coniferous Forest – Alpine Meadow Province (in much of New Mexico)

Tropical/Subtropical Desert Division

Chihuahuan Semi-Desert Province (in southwest Texas)

Many of the plant and animal taxa considered characteristic of the Chihuahuan desert and adjacent environments can be found in multiple ecoregions. For the most part, the specific plant communities, microhabitats, and quality of habitats determine the types of animals likely to occur in or use the area. The specific areas of concern for this project provide varying degrees of habitat suitability, and many taxa listed above may not occur within the project area due to limited habitat availability. Habitat quality is an important parameter to consider with regard to identifying species that may be impacted by project actions because much of the Rio Grande watershed is degraded compared to past conditions, before urbanization and water diversion/controls. Even though the habitats within the Rio Grande watershed (including in some cases those within or near project areas) have been and continue to be subject to varying degrees of degradation from a variety of sources (dams and other flood control measures, water diversion, urbanization, development, contaminants, water use, introduction of exotic species, etc.), the watershed maintains a significant biological value, especially where unique habitats remain.

Each of the unique habitats found within the Rio Grande watershed supports a wide variety of plant and animal species, including several that have been identified as State Species of Concern, rare, threatened, or endangered. Gil and Wilkins (2004) list 181 species within the Rio Grande watershed as threatened, endangered, or species of concern. These species are identified below for relevant portions of the Rio Grande watershed, from Percha Dam in New Mexico to the Gulf of Mexico.

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2.2 Rio Grande Canalization Project

The Rio Grande Canalization Project extends 105.4 miles from Percha Diversion Dam in New Mexico to the American Diversion Dam in El Paso, Texas. From Percha Dam to the Mesilla Diversion, channel width averages between 200 and 300 ft. The levees confine the floodplain to widths ranging from 600 to 1200 ft. Near the Selden Canyon, no levees have been constructed and the floodplain is naturally limited to 600 to 1200 ft. In the canyon the channel is slightly sinuous, at a value of 1.1, and has a sand bed. The gradient in this stretch of the river is roughly 4 ft/mi. From the Mesilla Diversion Dam to the American Dam, the floodplain is confined to an average width of 600 ft and the channel width is confined to an average of 220 ft. The channel here has a sand bed, a sinuosity of 1.05, and a channel slope of approximately 4 ft/mi (Fullerton and Batts 2003). The Canalization Project was constructed between 1938 and 1943 to provide flood control and facilitate water deliveries to the Rincon and Mesilla Valleys in New Mexico, El Paso Valley in Texas, and the Juarez Valley in Mexico, in accordance with the 1906 Convention Between the United States and Mexico for the Equitable Distribution of the Waters of the Rio Grande.

2.2.1 Vegetation Communities

The Rio Grande Canalization Project is located in the Trans-Pecos region of the Chihuahuan Desert. The natural vegetation in the Trans-Pecos region consists of grassland and desert shrub land. Of the grass types, tobosa (Hilaria mutica) and black grama (Bouteloua eriopoda) are among the most common. The desert shrub areas consist of creosote bush and tarbush. The riparian areas are dominated by invasive (non-native) salt cedar or tamarisk (Tamarix ramosissima), although native vegetation such as willow (Salicaceae), cottonwood (Populus deltoids) and screwbean mesquite-wolfberry are dominant in some communities, with ash (Fraxinus sp.) and desert willow (Chilopsis linearis) also present (USIBWC 2004). In particular, cottonwood-willow communities tend to occur upstream of Selden Canyon, particularly in the 1.2 miles downstream of Percha Dam, and screwbean mesquite-wolfberry and cottonwood-willow communities are dominant in Selden Canyon (WWF et al. 2001).

The cottonwood-willow communities in the Canalization Project consist of mainly gooding willow (Salix goodingii), cottonwoods and sometimes a dense understory of seepwillow (Baccharis salicifolia), plus a blend of grasses and forbs. Indicator species are the beaver and Southwestern willow flycatcher. The screwbean mesquite-wolfberry communities contain screwbean mesquite(Prosopis pubescens), wolfberry (Lycium torregi) and scattered honey mesquites. Forbs and grasses include alkali sacaton and saltgrass. Indicator species are mockingbirds (Mimus polyglottos), prrhuloxias (Cardinalis sinuatus), and verdin (Auriparus flaviceps).

Invasive species in addition to salt cedar that can be found in riparian zones of the Canalization Project include Russian olive (Elaeagnus angustifolia), especially in the northern reaches of the Project, and Russian thistle, or tumbleweed (Salsola iberica).

Salt cedar tends to spread rapidly in riparian areas of the Canalization project when they are not regularly mowed. Native cottonwood communities appear to be shrinking, with very little successful seed germination taking place (USIBWC 2004).

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Riparian vegetation communities in the watershed are mainly herbaceous with less than 20 percent cover of trees and shrubs, containing grasses, sedges, and forbs. Non-native species such as Russian thistle, red bladderpod (Sphaerophysa salsola), and jimson-weed (Datura stramonium ) are common. Without mowing, these herbaceous areas would likely convert quickly to woody salt cedar communities. Other riparian vegetation communities that can be found in the project floodplains are woodlands, shrublands, exposed ground, cropland and wetland. Bare exposed ground is a very common land cover type in the floodplains (USIBWC 2004). Within the levees between Las Cruces and El Paso, the riparian habitat is is extremely fragmented and low quality. There is little to no regeneration due to lack of flooding and frequent mowing (Fullerton and Batts 2003).

In the upland areas, common plants are snakeweed (Stachytarpheta spp), saltbush (Suaeda torreyana), and salt cedar. Land cover in upland areas can be classified into exposed ground, herbaceous, or woodland/shrubland, with exposed ground being abundant (USIBWC 2004).

An extensive list of plants in the Canalization project according to the 2004 USIBWC Biological Assessment is included in Appendix B, Item 1.

2.2.2 Wildlife Communities

The Rio Grande waters in the Canalization Project can be considered a lotic (flowing) habitat of low diversity. The river largely lacks certain characteristics of optimal aquatic habitat such as riffles, instream cover, and pooling. The river channel is mostly straight with very little variation in velocity. The bottom is sand and silt, and is not considered favorable to supporting a diverse aquatic life community. At least 22 species of fish live in the Rio Grande in the Canalization Project. These include channel catfish (Ictalurus punctatus), white crappie (Pomoxis annularis), bluegill (Lepomis macrochirus), common carp (Cyprinus carpio), river carpsucker (Carpiodes carpio), smallmouth buffalo (Ictiobus bubalus), gizzard shad (Dorsoma cepadianum), black bullhead (Ameiurus melas), flathead catfish (Pylodictis olivaris), largemouth bass (Micropterus salmoides), warmouth (Chaenobryttus gulosus), green sunfish (Lepomis cyanellus), longear sunfish (Lepomis megalotis), Western mosquitofish (Gambusia affinis), fathead minnow (Pimephales promelas), bullhead minnow (Pimephales vigilax), flathead catfish (Pylodictis olivaris), red shiner (Cyprinella lutrensis), longnose dace (Rhinichthys cataractae), spotted bass (Micropterus punctulatus), threadfin shad (Dorosoma petenense), white bass (Morone chrysops), and yellow perch (Morone Americana), (USIBWC 2004).

The Rio Grande shiner (Notropis jemezanus) and speckled chub (Macrhybopsis aestivalis) are extirpated from the Canalization Project (WWF et al. 2001).

The following mammals and reptiles were observed in the Canalization Project area during USIBWC field surveys in 2004, either by direct identification or identification of burrows or tracks: coachwhip (Masticophis flagellum), desert striped whipsnake (Masticophis taeniatus), western diamondback rattlesnake (Crotalus atrox), eastern fence lizard (Scleroporus undulatus), New Mexico whiptail (Cnemidophorous neomexicanus), beaver (Castor canadensis), gopher (Thomomys spp.), kangaroo rat, mice (Perognathus and Peromyscus spp.), raccoon (Procyon lotor), rock squirrel (Spermophilus variegatus), spotted ground squirrel (Spermophilus spilosoma), and wood rat (Neotoma spp.). Mature

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P:\9129-43926 (IBWC PEIS)\Biological Resources Survey\Second Draft\Section 2-Biological Resources Survey.doc and immature western burrowing owls (Athene cunicularia hypagaea), a Texas state listed rare species, have also been observed during USIBWC field surveys and by Texas Parks and Wildlife personnel. Burrows were located in the side of a levee road and in irrigation ditch embankments.

Other mammals of the area are beaver (Castor canadensis) and gray fox (Urocyon cineargentus). Migratory birds of the area include Clark’s and Western grebe (Aechmophorus clarkii and A. occidentalis), neotropical cormorant (Phalcrocorax olivaceus), and eared grebe (Podiceps migicollis), which all can be found on impoundments. Neotropical migratory birds such as common yellowthroat (Geothlypis trichas), yellow warbler (Dendroica petechia), and olive-sided flycatcher (Contopus borealis) also use the riparian areas. Western kingbirds (Tyrannus verticalis) are common (WWF et al. 2001).

Appendix B, Item 2, is a list of birds that were observed during the 2004 USIBWC field surveys in the Canalization Project.

2.2.3 Threats to Vegetation and Wildlife Communities

Flow in the Rio Grande in the Canalization Project is interrupted on a seasonal basis.

Periods of complete dryness occur, and these are a challenge for aquatic and water-dependent wildlife. When there is flow in the reach it has little of the variation that would be typical of a natural stream hydrograph. Although sediment-free water is released from Caballo Dam the flow quickly picks up sediment and deposits it in both the Canalization and Rectification projects. Arroyos also deposit sediment in the main channel that is not removed by the stable river flow. This sediment is manually removed. Salinity can reach high levels when there is water in the river. The salt build up in the soils, and poor water quality pose challenges in the restoration of the riparian habitat (Fullerton and Batts 2003, WWF et al. 2001).

Much of the vegetation in the floodplain is noxious and/or invasive, including salt cedar and Russian olive, the spread of which is controlled by mowing.

Human activities and development in the floodplain such as levees, communities, agriculture, and water and transportation infrastructure has hindered the ability of vegetation and wildlife to thrive in the area by disconnecting portions of the floodplain and hindering natural geomorphic channel evolution (Fullerton and Batts 2003). Overgrazing has also affected floodplains in some areas (WWF et al. 2001).

2.2.4 Threatened and Endangered Species

The Fish and Wildlife Coordination Act (FWCA), 16 USC 661 et seq., requires federal agencies involved in actions that will result in the control or structural modification of any natural stream or body of water for any purpose, to take action to protect the fish and wildlife resources that may be affected by the action.

The Endangered Species Act (ESA), 16 USC 1536 et seq., provides a program for the conservation of threatened and endangered plants and animals and the habitats in which they are found. The United States Fish and Wildlife Service (USFWS) of the

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Department of the Interior maintains the species list, which currently contains 988 endangered species (599 are plants) and 276 threatened species (147 are plants).

Species include birds, insects, fish, reptiles, mammals, crustaceans, flowers, grasses, and trees. Anyone can petition the USFWS to include a species on this list. The law prohibits any action, administrative or real, that results in a "taking" of a listed species, or adversely affects habitat. Taking is defined by the USFWS as harming, hunting, capturing, or killing, where harming includes altering the habitat to the point that it kills or injures endangered or threatened species through the impairment of its breeding, reproductive, and feeding behaviors. Likewise, import, export, interstate, and foreign commerce of listed species are all prohibited.

In the State of New Mexico, the New Mexico Department of Fish and Game has jurisdiction over the conservation, protection, and management of wildlife, native plants, and habitat necessary to maintain biologically sustainable populations. In Texas the Texas Parks and Wildlife Department has similar jurisdiction. Both the states of New Mexico and Texas maintain lists of endangered, threatened, and rare or sensitive species apart from the Federal lists.

2.2.4.1 Federal

The project lies in two states and three counties: Sierra and Doña Ana Counties, New Mexico and El Paso County, Texas. Approximately seven river miles are in Sierra County, 80 are in Doña Ana County, and 18 are in El Paso County.

Based on current listings under the Endangered Species Act of 1973, nine federally listed endangered species may occur in Sierra, Dona Ana, or El Paso Counties, as well as three federally listed threatened species and two federally listed candidate species.

Not all species on the federal or state county lists share the same probability of occurring in the county. Some are migrants and may only pass through the county seasonally. Others are only known to occur in the county historically, or are considered extirpated (no longer present). There are no federally designated critical habitats in the project area. The federally listed species and their classifications are presented in Table 2-1. The codes in the “habitat presence” column classify each species according to the presence or absence of habitat in the flood control project area. These classifications are based on available previous studies, general knowledge of the typical habitat of the species, and of typical conditions along the Rio Grande in the project area. They describe the general conditions of the project as a whole and are not meant to replace the results of field surveys.

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Table 2-1. Federally Listed Species for Sierra, Dona Ana, and El Paso Counties Species Name Federal

Status Habitat Presence Counties Listed

Birds Bald eagle (Haliaeetus leucocephalus) AD, T 1 Sierra; Dona Ana Interior least tern (Sterna antillarum) E 2 Dona Ana; El Paso Mexican spotted owl (Strix occidentalis lucida) T 5 Sierra; Dona Ana; El Paso Northern aplomado falcon (Falco femoralis septentrionalis) E 5 Sierra; Dona Ana; El Paso Southwestern willow flycatcher (Empidonax traillii estimus) E 1 Sierra; Dona Ana; El Paso Whooping crane (Grus americana) E, EXPN 5 Sierra Yellow-billed cuckoo (Coccuzus americanus) C 4 Sierra; Dona Ana; El Paso Fishes Gila trout (Oncorhynchus gilae) E 5 Sierra Rio Grande silvery minnow (Hybognathus amarus) E 3 Sierra; Dona Ana Plants Sneed pincushion cactus (Coryphantha sneedii) E 5 Dona Ana; El Paso Todsen’s pennyroyal (Hedoma todsenii) E 5 Sierra Mammals Black-footed ferret (Mustela nigripes) E, EXPN 5 Sierra Black-tailed prairie dog (Cynomys ludovicianus) C 5 Sierra Amphibians Chiricahua leopard frog (Rana chiricahuensis) T 5 Sierra Source: United States Fish & Wildlife Service 2004 E-endangered, T-threatened, C-candidate, AD-proposed delisting, SAT-similarity of appearance to a threatened taxon, DM-delisted recovered and being monitored first five years; EXPN-non-essential experimental population 1-habitat exists in project; 2-migratory species, seasonal habitat exists in project; 3-species believed to be extirpated from project area;

4-project area lies within geographic species range and is likely to include habitat; 5-suitable habitat does not exist in project

In January of 2004, the USIBWC published a Biological Assessment for the River Management Alternatives for the Rio Grande Canalization Project. In this document, the presence or absence of suitable habitat for state and federal endangered and threatened species in the Rio Grande Canalization Project was determined based on a literature review and field surveys. Of the 14 species listed above, eight (northern aplomado falcon, Mexican spotted owl, whooping crane, Gila trout, sneed pincushion cactus, todsen’s pennyroyal, black-footed ferret, and chiricahua leopard frog) do not have suitable habitat present in the Canalization Project, according to the 2004 biological assessment. The remaining six species may have suitable habitat in the Canalization project, since they were not ruled out in the 2004 Biological Assessment.

Habitats for these species are described below.

Bald eagles live in areas similar to the riparian shrubland and woodland, and plaustrine woodland in the Canalization Project. The potential habitat is found mostly in the northern part of the Project, in southern Sierra County. Bald eagles have previously been sighted in this part of the Canalization Project (USIBWC 2004).

Interior least terns live on river sandbars and beaches. These types of sandbars exist in the Canalization Project. At least one interior least tern was observed in September of 2000 in the Canalization project, both flying and resting on sand bars. Although there are not thought to be suitable nesting areas for the interior least tern in the Project, the area can be used for feeding and resting during migration (USIBWC 2004).

The southwestern willow flycatcher breeds in dense riparian habitats that include shrubs and medium sized trees, and has been observed in the Seldon Canyon region of the Rio Grande living in a salt cedar community. In the Canalization Project but

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The black-tailed prairie dog, yellow-billed cuckoo, and Rio Grande silvery minnow were not addressed in the 2004 biological assessment. Their general habitats are described below.

The black-tailed prairie dog lives in large family groups in dry, flat, short grassland with sparse vegetation that may be overgrazed (TPW 2004).

The yellow-billed cuckoo requires riparian areas for survival, and dense understory foliage for nesting. The bird nests in willow, mesquite, cottonwood, and hackberry (Celtis pallida) (TPW 2004).

The Rio Grande silvery minnow has historically lived in the Rio Grande and Pecos river systems and canals, in the pools and backwaters of medium to large streams with low or moderate gradient. Stream bottoms can be mud, sand, or gravel. The fish eats algae and organic matter in the bottom mud and ooze (TPW 2004).

2.2.4.2 State

The species in Table 2-2 for Doña Ana and Sierra Counties are listed by the New Mexico Department of Fish and Game, and may occur in the Rio Grande watershed between Caballo Dam and El Paso according to the Natural Heritage New Mexico database. The area corresponds to the 8-digit Hydrologic Unit Code (HUC) No.

13030102. The species listed for El Paso County are endangered or threatened and may occur in El Paso County according to the Texas Parks and Wildlife Department.

Table 2-2. New Mexico State Listed Species for Rio Grande Watershed Caballo Dam through El Paso;

and Texas State Listed Species for El Paso County

Species Name State Status

Habitat Presence Counties Listed

Birds American peregrine falcon (Falco peregrinus anatum) T 2 Doña Ana Arctic peregrine falcon (Falco peregrinus tundrius) T 2 El Paso Broad-billed hummingbird (Cynanthus latirostris) T 4 Doña Ana Common black hawk (Buteogallus anthracinus) T 4 El Paso Common ground-dove (Columbina passerina) E 4 Doña Ana; Sierra Mexican spotted owl (Strix occidentalis lucida) T 5 El Paso Northern aplomado falcon (Falco femoralis septentrionalis) E 5 Doña Ana; El Paso Southwestern willow flycatcher (Empidonax traillii extimus) E 1 Doña Ana; Sierra; El Paso Zone-tailed hawk (Buteo albonotatus) T 4 El Paso Mollusks Dona Ana talussnail (Sonorella todseni) T 5 Doña Ana Ovate vertigo (Vertigo ovata) T 5 Doña Ana; Sierra Fishes Bluntnose shiner (Notropis simus pecosensis) T 3 El Paso Mexican tetra (Astyanax mexicanus) T 3 Doña Ana Rio Grande silvery minnow (Hybognathus amarus) E 3 Doña Ana; El Paso Mammals Black bear (Ursus americanus) T 5 El Paso Black-footed ferret (Mustela nigripes) E 5 El Paso Desert bighorn sheep ( Ovis canadensis mexicana) E 5 Doña Ana; Sierra

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Table 2-2. New Mexico State Listed Species for Rio Grande Watershed Caballo Dam through El Paso;

and Texas State Listed Species for El Paso County

Species Name State Status

Habitat Presence Counties Listed

Gray wolf (Canis lupus) E 5 El Paso

Organ Mountains Colorado chipmunk (Tamias quadrivittatus australis) T 5 Doña Ana

Reptiles Chihuahuan desert lyre snake (Trimorphodon vilkinsonii) T 4 El Paso Chihuahuan mud turtle (Kinosternon hirtipes) T 4 El Paso Gila monster ( Heloderma suspectum) E 5 Doña Ana Texas horned lizard (Phrynosoma cornutum) T 1 El Paso Trans-Pecos black-headed snake (Tantilla cucullata) T 4 El Paso Plants Branching penstemon (Penstemon ramosus) S 5 Doña Ana; Sierra Mosquito plant (Agastache cana) S 5 Doña Ana; Sierra Night-blooming cereus (Peniocereus greggii var greggii) E 4 Doña Ana; Sierra Nodding rockdaisy (Perityle cernua) S 5 Doña Ana Organ evening-primrose (Oenothera organensis) S 5 Doña Ana Organ Mountain foxtail-cactus (Escobaria organensis) E 5 Doña Ana Pink flower flameflower (Talinum longipes) S 5 Doña Ana; Sierra Plank’s catchfly (Silene plankii) S 5 Doña Ana; Sierra Sand prickly-pear (Opuntia arenaria) E 5 Doña Ana Smooth bur-cucumber (Sicyos glaber) S 5 Doña Ana Smooth figwort (Scrophularia laevis) S 5 Doña Ana Sneed’s pincushion cactus (Coryphantha sneedii var. sneedii) E 5 Doña Ana; El Paso Standley’s whitlow-grass(Draba standleyi) S 5 Doña Ana Villard’s pincushion cactus (Escobaria villardii) E 5 Doña Ana Source: Natural Heritage New Mexico 2004 E-endangered, T-threatened, S-Sensitive Plant 1-habitat exists in project; 2-migratory species, seasonal habitat exists in project; 3- species believed to be extirpated from project area; 4-project area lies within geographic species range and is likely to include habitat; 5-suitable habitat does not exist in project

In addition to the species listed above, a white-faced ibis (Plegadis chihi) was spotted in April of 2000 during a field survey on a vegetated sandbar in the Canalization Project area. The white-faced ibis is threatened according to the state of Texas, but is not listed as potentially occurring in El Paso County or in the Rio Grande watershed below Caballo Dam in New Mexico. The Canalization Project provides little of the marsh habitat used for the bird’s nesting, but the sandbars and wetlands in the project may be in use for feeding and resting (Parsons 2001).

2.3 Rectification Project

The Rio Grande Rectification Project was constructed between 1934 and 1938 and extends 86 river miles from El Paso to Fort Quitman, Texas. The purpose of the project is to stabilize the international river boundary and to provide flood protection for both countries in urban, suburban, and agricultural areas. The main components of the project were strengthening the river channel by constructing a new channel and developing a floodway by constructing levees on both sides of the river. The channel strengthening process entailed removing meanders and resulted in a reduction in the river length from 155 to 86 miles. The Rectification Project reduced the sinuosity from 2 to 1.1, and increased the gradient to 3.3 ft/mi. The current channel has a sand bed and receives minimal upstream flows, with a base flow created by agricultural returns

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2.3.1 Vegetation Communities

The project lies in the Trans-Pecos region of Texas, in the Chihuahuan biotic province. Natural vegetation is arid and consists of desert shrub communities.

Most of the natural vegetation in the Rio Grande corridor in El Paso and Hudspeth counties has been replaced by cropland and urban development. The natural vegetation community that exists to the east of the Rio Grande is called Mesquite- Sandsage Shrub (Proposis glanulosa-Artemisia filifolia) according to the Texas state system (Texas Parks and Wildlife (TPW) 1984). In Hudspeth County some of the natural vegetation to the east of the Rio Grande is Creosote Bush-Lechuguilla Shrub (Larrea tridentate-Agave lecheguilla). Table 2-3 lists plant life that can be found in these communities.

Table 2-3. Plants Typical Of Mesquite-Sandsage Shrub And Creosote Bush-Lechuguilla Shrub Mesquite-Sandsage Shrub Creosote Bush-Lechuguilla Shrub El Paso and Hudspeth Counties Hudspeth County Black grama Blue grama Broom snakeweed Chino grama Devil's claw Fourwing saltbush Mormon tea Palmella Sand dropseed Spike dropseed Sotol

Bouteloua eriopoda Bouteloua gracilis Gutierrezia sarothrae Bouteloua breviseta Harpagophytum procumbens Atriplex canescens Ephedra trifurca Palmellales Sporobolus cryptandrus Sporobotus cryptandrus Dasylirion wheeleri

Allthorn Black grama Catclaw Cenizo Chino grama Fuffgrass Guayacan Javelina bush Lotebush Mariola Mesquite Ocotillo Pitaya Pricklypear Tasajillo Range ratany Skeletonleaf goldeneye Tarbush Whitebrush Whitethorn acacia Yucca

Koeberlinia spinosa Bouteloua eriopod) Acacia greggii Leucophyllum candidum Bouteloua breviseta Erioneuron pulchellum Guaiacum angustifolium Condalia ericoides Ziziphus obtusifolia Parthenium incanum Prosopis Sp.

Fouqueiria splendens Hylocereus undatus Cactoblastis cactorum Opuntia leptocaulis Krameria erecta Viguiera stenoloba Flourensia cernua Aloysia gratissima Acacia constricta Yucca filamentosa

Source: McMahan et al. 1984

In this reach the salt cedar has invaded much of the riparian area, and it has been estimated that only 60 acres of cottonwood-willow remain between El Paso and Candelaria due to soil salinity (Fullerton and Batts 2003).

This remaining cottonwood- willow contains scattered mature or over-mature Fremont cottonwood and Gooding willow. The understory is a dense mix of seepwillow, grasses, forbs and dock. Some screwbean mesquite- wolfberry communities similar to those in the Canalization Project can be found in the reach between El Paso and Candelaria. They are typically in the floodplains outside bands of salt cedar next to the river. Indicator species are black-tailed gnatcatcher (Polioptila

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2.3.2 Wildlife Communities

In El Paso and Hudspeth Counties, 7 species of wood warblers, 10 species of sparrows and towhees, 9 species of swans, geese, and ducks, 5 species of tyrant flycatchers, and 50 other bird species can be found. Eleven species of bats, rats, mice and squirrels can be found in the counties, plus 10 other mammal species including deer, gophers, black-tailed jackrabbit (Lepus californicus), and desert cottontail (Sylvilagus auduboni).

Six species of toads, spade-foots, and frogs occur in the counties. In addition, 17 species of reptiles, mostly snakes with some lizards (e.g., several species of whiptails) can be found. Most of the birds occur in riparian environments, while most of the other animals occur mainly in desert and grassland areas (USACE 1999).

In the Rio Grande between El Paso and Alamito Creek near Presidio, fish species include 22 native species and four introduced species. These include a variety of gars, herrings, carps, minnows, suckers, characins, bullhead catfishes, pupfishes, livebearers, and silversides. Many of these are considered relatively common (USACE 1999).

Burrowing owls (Athene cunicularia) have been observed by Texas Parks and Wildlife personnel living in burrows in the levees of the Rectification project. The Western burrowing owl (Athene cunicularia hypugaea) is listed by the Texas Parks and Wildlife Department as a rare species.

2.3.3…