[Federal Register Volume 71, Number 205 (Tuesday, October 24, 2006)]
[Notices]
[Pages 62295-62297]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-17680]


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INTERNATIONAL BOUNDARY AND WATER COMMISSION UNITED STATES AND MEXICO


United States Section; Notice of Availability of a Draft Final 
Environmental Assessment and Finding of No Significant Impact for 
Improvements to the Mission and Common Levee Systems, in the Lower Rio 
Grande Flood Control Project, Located in Hidalgo County, TX

AGENCY: United States Section, International Boundary and Water 
Commission (USIBWC), United States and Mexico.

ACTION: Notice of Availability of Draft Environmental Assessment (EA) 
and Finding of No Significant Impact (FONSI).

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SUMMARY: Pursuant to Section 102(2)(c) of the National Environmental 
Policy Act of 1969; the Council on Environmental Quality Final 
Regulations (40 CFR parts 1500 through 1508); and the United States 
Section's Operational Procedures for Implementing Section 102 of NEPA, 
published in the Federal Register September 2, 1981, (46 FR 44083); the 
United States Section hereby gives notice that the Draft Environmental 
Assessment and Finding of No Significant Impact for Improvements to the 
Mission and Common Levee Systems, in the Lower Rio Grande Flood Control 
Project, located in Hidalgo County, Texas are available.

FOR FURTHER INFORMATION CONTACT: Gilbert G. Anaya, Supervisory 
Environmental Protection Specialist; Environmental Management Division; 
United States Section, International Boundary and Water Commission; 
4171 N. Mesa, C-100; El Paso, Texas 79902. Telephone: (915) 832-4702, 
e-mail: [email protected].

Supplemental Information:

Background

    The USIBWC is authorized to construct, operate, and maintain any 
project or works projected by the United States of America on the Lower 
Rio Grande Flood Control Project (LRGFCP) as authorized by the Act of 
the 74th Congress, Sess. I Ch. 561 (H.R. 6453), approved August 19, 
1935 (49 Stat. 660), and codified at 22 U.S.C. Section 277, 277a, 277b, 
277c, and Acts amendatory thereof and supplementary thereto. The LRGFCP 
was constructed to protect urban, suburban, and highly developed 
irrigated farmland along the Rio Grande delta in the United States and 
Mexico.
    The USIBWC, in cooperation with the TPWD, prepared this Draft 
Environmental Assessment (Draft EA) for the proposed action of raising 
the Mission and Common Levee Systems located in Hidalgo County, Texas 
to improve flood control. These two adjacent levee systems are part of 
the LRGFCP that extends approximately 180 miles from the Town of 
Pe[ntilde]itas in south Texas to the Gulf of Mexico. The Mission Levee 
extends approximately 12 miles along the Rio Grande, downstream from 
the Town of Pe[ntilde]itas. The Common Levee System, approximately 5.3 
miles long, consists of the Common Levee and Anzalduas Dike, which 
connects the Common Levee to Anzalduas Dam.

Proposed Action

    The Proposed Action would increase flood containment capacity of 
the Mission and Common Levee Systems to meet the 3-foot freeboard 
design criterion for flood protection. Height increases between 2 and 6 
feet are typically needed to reach the design freeboard value 
throughout the Mission Levee System. For the Common Levee, typical 
increases in levee height range from 3 to 8 feet, and for the Anzalduas 
Dike, from 0 to 4 feet. The increase in levee height will also expand 
the levee footprint by lateral extension of the structure.
    Along with the increase in levee height, structural improvements 
will also be required for levee segments throughout the downstream 
reach of the Mission Levee and the Common Levee System where seepage is 
a potential problem. These improvements will consist of either a slurry 
cutoff barrier or a riverside impermeable liner.

Alternatives to the Proposed Action

    A No Action Alternative was evaluated for the Mission and Common 
Levee Systems. This alternative will retain the existing configuration 
of the two systems, as designed over 30 years ago, and the current 
level of protection currently associated with this system. Under severe 
storm events, current containment capacity may be insufficient to fully 
control Rio Grande flooding, with risks to personal safety and 
potential property damage.

Summary of Findings

    Pursuant to National Environmental Policy Act (NEPA) guidance (40 
Code of Federal Regulations 1500-1508), The President's Council on 
Environmental Quality issued regulations for NEPA implementation which 
included provisions for both the content and procedural aspects of the 
required Environmental Assessment. The USIBWC completed an EA of the 
potential environmental consequences of raising the Mission and Common 
Levee Systems to meet current requirements for flood control. The EA, 
which supports this Finding of No Significant Impact, evaluated the 
Proposed Action and No Action Alternative.

Mission Levee System Evaluation

No Action Alternative

    The No Action Alternative was evaluated as the single alternative 
action to the Proposed Action. The No Action Alternative will retain 
the current configuration of the Mission Levee System, with no impacts 
to biological and cultural resources, land use, community resources, or 
environmental health issues. In terms of flood protection, however, 
current containment capacity under the No Action Alternative may be 
insufficient to fully control Rio Grande flooding under severe storm 
events, with

[[Page 62296]]

associated risks to personal safety and property.

Proposed Action

    Biological Resources. Improvements to the Mission Levee corridor 
would affect plant communities through excavation and fill activities. 
Impacts would occur on the levee sidewalls where fill will be added, 
and within the expanded levee footprint area. Potential acreage removed 
and impacts to four vegetation communities identified along the Mission 
Levee project area are as follows: (1) removal of up to 34.2 acres of 
mesquite-acacia woodland, in various stages of succession, along the 
levee corridor, (approximately 19 percent of thorn woodland located 
within the levee right-of-way); (2) removal of up to 77.5 acres of 
herbaceous vegetation along the levee corridor; impacts would be short-
term as herbaceous vegetation would be rapidly re-established and is 
represented primarily by Bufflegrass, an invasive species; (3) up to 
1.1 acres of wetlands/riparian communities will be modified along an 
irrigation intake channel; these communities are represented primarily 
by phragmites--arundo emergent and semi-emergent plants; and (4) 
minimum removal of agricultural lands is anticipated, less than 0.5 
acre.
    Thorn woodlands and wetlands along the Mission levee corridor 
provide the best quality wildlife habitat. Some wildlife species may 
utilize these areas as transit corridors, but that usage is likely 
limited. Natural resource areas with quality wildlife habitat adjacent 
to the riverside of the Mission Levee system occupy approximately 33 
percent of the 12.1 miles total length, as follows: 2.4 miles along the 
Lower Rio Grande Valley (LRGV) National Wildlife Refuge; 1.3 miles 
along the Bentsen-Rio Grande Valley State Park; and 0.3 mile along the 
Chihuahua Woods Preserve. Based on regional distribution, 26 Threatened 
and Endangered (T&E) species habitat could be found in the project 
area. Improvements to the existing levee system are not likely to 
affect those habitats. Consultation with TPWD and the U.S. Fish & 
Wildlife Service (USFWS) will be conducted to schedule construction 
activities to minimize potential impacts on those species and their 
habitat.
    Twenty-one wetlands and open water areas that met criteria as 
jurisdictional waters of the United States were identified within the 
Mission Levee right-of-way (ROW). None of these wetlands will be 
directly impacted by the levee expansion project. A single wetlands 
area, located outside the current levee ROW but within the potential 
levee expansion area, will be impacted by construction activities at 
the new levee crossing at the Pe[ntilde]itas Pumping Plant intake 
channel. Construction activities may remove approximately 1 acre from 
wetlands that flank the irrigation intake channel.
    Cultural Resources. According to a preliminary cultural resources 
evaluation conducted in support of the EA preparation, improvements to 
the Mission Levee System have a potential to impact historic 
archaeological materials at six locations, as well as a known 
prehistoric archaeological resource (41HG143). No areas considered to 
be high probability for the occurrence of unknown prehistoric 
archaeological sites were identified in previous studies or during the 
current archival research. However, areas of historic occupation 
sometimes contain a prehistoric component and should also be considered 
as possible locations for prehistoric archaeological sites because 
European settlers also considered prehistorically utilized landform 
surfaces (stable surfaces) as desirable living surfaces. Four historic-
age resources exist within the current Mission Levee ROW and are 
engineering elements of the levee system. These resources will likely 
be redesigned to some extent by proposed modifications to the levee, or 
may undergo a moderate visual impact by encroachment of the expanded 
levee footprint. One additional historical resource, the La Lomita 
Chapel, is located near the Mission Levee project within a National 
Register of Historic Places District, but outside the potential effects 
area.
    Water Resources. Improvements to the levee system will increase 
flood containment capacity to control the design flood event as 
evaluated by hydraulic modeling. A minimum change in floodwater surface 
elevation, less than 1 inch, is anticipated as a result of the levee 
height increase for the Mission Levee System. Levee footprint expansion 
will not affect water bodies with exception of the new crossing at the 
Pe[ntilde]itas Pumping Plant intake channel.
    Land Use. The approximate 113-acre expansion of the Mission Levee 
will impact mostly herbaceous vegetation dominated by invasive species 
(approximately 78 acres). Up to 34 acres of thorn woodland, a higher 
quality habitat, will also be removed. Removal of agricultural lands 
will be limited to 0.5 acre. Construction impacts along sections of the 
Riverside Subdivision of Madero will be temporarily affected by 
construction activities.
    Community Resources. Improvements to the Mission Levee System, 
individually or in combination with the Common Levee System, represent 
an influx of federal funds into Hidalgo County and will have a positive 
local economic impact; however, the benefit will be limited to the 
construction period and represents less than 0.2 percent of the annual 
county employment, income, and sales values. No adverse impacts to 
disproportionately high minority and low-income populations were 
identified. Minimum utilization of public roads during construction is 
anticipated; a temporary increase in access road use will be required 
for equipment mobilization to staging areas.
    Environmental Health Issues. Improvements to the Mission Levee 
System represent less than 1 percent of the Hidalgo County annual 
emissions inventory for five air criteria pollutants. Moderate 
increases in ambient noise levels will result from excavation and fill 
activities, with no transient or long-term exposures above threshold 
values for adverse impacts. No waste storage or disposal sites were 
identified within the expanded Mission Levee footprint and its 
vicinity.
    Indirect Impacts. No significant indirect impacts of the Mission 
Levee Improvements were identified.
    Best Management Practices and Mitigation. Engineering design 
measures will include optimization of the levee expansion alignment to 
the extent possible to avoid impact to sensitive vegetation and natural 
resources management areas, including Bentsen-Rio Grande Valley State 
Park and the LRGV National Wildlife Refuge. Mitigation for cultural 
resources, as required, will be coordinated between the Texas Historic 
Commission and the USIBWC. Levee expansion will be rerouted across the 
Edinburg irrigation intake channel to protect the historic-age 
Pe[ntilde]itas pumping station. Prior to construction, site surveys 
will determine the type (herbaceous or woody) vegetation to be removed 
and separation between construction corridor(s) and boundaries of 
wetlands.
    During construction, best management practices (BMP) include 
development of a storm water pollution prevention plan to minimize 
impacts of receiving waters, including use of sediment barriers and 
soil wetting to minimize erosion. To the extent possible, construction 
activities will be scheduled to occur outside the migratory bird 
nesting season.
    Following construction, expanded levees and the construction 
corridor will be promptly revegetated using native herbaceous or wooded 
indigenous species, as agreed with the

[[Page 62297]]

natural resources management agency where the corridor is located. The 
USIBWC, in coordination with the USFWS, is developing approximately 30 
acres of new wetlands as mitigation for levee improvements throughout 
the LRGFCP.

Common Levee System Proposed Action and Alternatives

No Action Alternative

    The No Action Alternative was evaluated as the single alternative 
action to the Proposed Action. The No Action Alternative will retain 
the current configuration of the Common Levee System, with no impacts 
to biological and cultural resources, land use, and soil, community 
resources, or environmental health. In terms of flood protection, 
however, current containment capacity under the No Action Alternative 
may be insufficient to fully control Rio Grande flooding under severe 
storm events, with associated risks to personal safety and property.

Proposed Action

    Biological Resources. The Common Levee System corridor runs 
primarily through agricultural areas. Approximately 1 mile of the total 
length of the 5.2-mile levee system runs along two units of the LRGV 
National Wildlife Refuge. No thorn woodland will be removed along the 
levee expansion, while 3.9 acres of low density woodland will be 
removed along Anzalduas Dike. The 3.9 acres along the Anzalduas Dike 
represent 10 percent of the total area of thorn woodland within the 
Common Levee System (including both the Common Levee and the Anzalduas 
Dike areas). A single wetlands/open water area located within the 
Common Levee ROW is located outside the 100-foot buffer area for the 
proposed levee expansion, and will not be affected by construction 
activities. Removal of T&E species habitat, including woodland habitat 
suitable for the ocelot, would be minimal along the Common Levee System 
corridor. For other species whose habitat is potentially present near 
the levee corridor, construction activities will be scheduled to 
minimize impacts to those species and their habitat.
    Cultural Resources. No areas of high probability for the occurrence 
of unknown prehistoric archaeological sites have been reported along 
the Common Levee System, and none were identified during the current 
archival research conducted in preparation of the EA. Preliminary 
investigations indicate that two historic-age resources exist within 
the current Mission Levee ROW and are engineering elements of the levee 
system. These resources will undergo minor modifications at the levee 
tie-ins, or may undergo a moderate visual impact by the encroachment of 
the expanded levee footprint.
    Water Resources. The Common Levee System was evaluated with the 
updated hydraulic model to determine if changes to water surface 
elevations will be affected by the proposed improvements to the levee 
system. As in the case of the Mission Levee System, a minimum change in 
floodwater surface elevation, less than 1 inch, is anticipated as a 
result of the levee height increase.
    Land Use. The proposed expansion of the Common Levee System will 
occur entirely within the ROW. No urban development is located near the 
proposed levee expansion area. The expansion will remove approximately 
62 acres of herbaceous vegetation along the Common Levee and 
approximately 6 acres of herbaceous vegetation along the Anzalduas 
Dike. Alignment of the levee expansion will be adjusted to minimize 
removal of established wooded vegetation along the Gabrielson and 
Cottam Units of the LRGV National Wildlife Refuge. Anzalduas Dam County 
Park, where Anzalduas Dike is located, will be temporarily affected 
during project construction. No impacts to agricultural lands are 
anticipated.
    Community Resources. Improvements to the Common Levee System, 
individually or in combination with the Mission Levee System, represent 
an influx of federal funds into Hidalgo County that will have a 
positive local economic impact; however, the benefit will be limited to 
the construction period and represents less than 0.2 percent of the 
annual county employment, income, and sales values. No adverse impacts 
to disproportionately high minority and low-income populations were 
identified. Minimum utilization of public roads during construction is 
anticipated; a temporary increase in use of the access road will be 
required for equipment mobilization to staging areas.
    Environmental Health Issues. Construction of the Common Levee 
System represents less than 1 percent of the Hidalgo County annual 
emissions inventory for five air criteria pollutants. Moderate 
increases in ambient noise levels will result from excavation and fill 
activities, with no transient or long-term exposures above threshold 
values for adverse impacts. No waste storage or disposal sites were 
identified within the expanded levee footprint and its vicinity.
    Best Management Practices and Mitigation. Engineering design 
measures will include optimization of the levee expansion alignment to 
the extent possible to avoid impact to sensitive vegetation and natural 
resources management areas within the LRGV National Wildlife Area. 
Mitigation for cultural resources, as required, will be coordinated 
between the Texas Historic Commission and the USIBWC. During 
construction, BMPs include development of a storm water pollution 
prevention plan to minimize impacts of receiving waters, including use 
of sediment barriers and soil wetting to minimize erosion. Following 
construction, expanded levees and the construction corridor will be 
promptly revegetated using native herbaceous indigenous species.

Availability

    Single hard copies of the Draft Environmental Assessment and 
Finding of No Significant Impact may be obtained by request at the 
above address. Electronic copies may also be obtained from the USIBWC 
Home Page at www.ibwc.state.gov.

    Dated: October 17, 2006.
Susan Daniel,
General Counsel.
[FR Doc. E6-17680 Filed 10-23-06; 8:45 am]
BILLING CODE 7010-01-P