[Federal Register Volume 72, Number 230 (Friday, November 30, 2007)]
[Notices]
[Pages 67754-67756]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-23029]


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INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO


United States Section; Notice of Availability of a Final 
Environmental Assessment and Final Finding of No Significant Impact for 
Improvements to the Main and North Floodways Levee System in the Lower 
Rio Grande Flood Control Project, Hidalgo, Cameron and Willacy 
Counties, TX

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

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

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SUMMARY: Pursuant to Section 102(2)(c) of the National Environmental 
Policy Act (NEPA) of 1969, the Council on Environmental Quality Final 
Regulations (40 CFR parts 1500 through 1508), and the United States 
Section, International Boundary and Water Commission's (USIBWC) 
Operational Procedures for Implementing Section 102 of NEPA, published 
in the Federal Register September 2, 1981, (46 FR 44083); the USIBWC 
hereby gives notice of availability of the Final Environmental 
Assessment and FONSI for Improvements to the Main and North Floodways 
Levee System, in the Lower Rio Grande Flood Control Project, located in 
Hidalgo, Cameron and Willacy Counties, Texas.

FOR FURTHER INFORMATION CONTACT: Daniel Borunda, 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) 832-4767; e-mail: 
[email protected].

DATES: The Final EA and FONSI will be available November 30, 2007.

SUPPLEMENTARY 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 Texas Parks and Wildlife 
Department, prepared this EA for the proposed action to improve flood 
control along sections of the Main and North Floodways Levee System 
located in Hidalgo, Cameron, and Willacy Counties, Texas. This levee 
system is 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 
Main and North Floodway Levee system extends approximately 75 levee 
miles, downstream from Anzalduas Dam, and extending near the town of 
Mercedes to the Laguna Madre northwest of Arroyo City, Texas.

Proposed Action

Alternatives to the Proposed Action

    The Proposed Action would increase the flood containment capacity 
of the Main and North Floodways Levee System by raising the elevation 
of a number of levee segments for improved flood protection. Fill 
material would be added to the existing levee to bring height to its 
original design specifications, or to meet a 2 feet freeboard design 
criterion. Typical height increases in improvement areas would be less 
than 1 foot and would not require expansion of the existing levee 
footprint.
    In some locations, up to 2 feet of fill material would be placed on 
top of the

[[Page 67755]]

levee, extending the levee footprint up to a maximum of 12 feet from 
the current toe of the levee. This expansion would take place along the 
approximately 20 foot service corridor currently utilized for levee 
maintenance, inside the maintained floodway, and entirely within the 
flood control project right-of-way. In some instances, adjustment in 
levee slope would be made to eliminate the need for levee footprint 
expansion, when required due to engineering considerations or for 
protection of biological or cultural resources. The need for excavation 
outside the levee structure is not anticipated.

Summary of Findings

    Pursuant to 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 Main and North Floodways Levee System 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.

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 would retain 
the current configuration of the Main and North Floodways 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 associated risks to personal safety and 
property.

Proposed Action

Biological Resources
    Improvements to the levee system require placement of fill material 
that would affect grassed areas at levee footprint expansion locations. 
All expansion would take place along the current levee service 
corridor, limiting vegetation removal to invasive-species grasslands; 
this grass cover is expected to be rapidly re-established after project 
completion.
    No significant effects are anticipated on wildlife habitat in the 
vicinity of the levee system, including potential habitat for 
threatened and endangered species. While approximately 17 percent of 
levee system is adjacent to natural resources conservation areas, only 
a small fraction would fall within levee improvement areas. In areas 
requiring levee footprint expansion, no woodland communities would be 
impacted; impacts on vegetation would be limited to non-native 
grasslands along the levee, of very limited value as wildlife habitat. 
No wetlands are located within the potential levee expansion area.
Cultural Resources
    Improvements to the Main and North Floodways Levee System are not 
expected to adversely affect known archaeological or historical 
resources. Typically, placement of fill material over the existing 
levee would not expand the levee footprint; when levee footprint 
expansion is needed, expansion would take place within the service 
corridor currently used for levee maintenance. High-Probability Areas 
(HPAs) identified along the levee system would be located outside the 
improvement areas, with minor exceptions. In areas where HPAs are 
located near improvement areas, the need for footprint expansion would 
be eliminated by adjusting levee slope to retain current location of 
the toe of the levee.
    Cultural resources located in the general vicinity of the levee 
system include historic age structures. Potential historic-age 
resources near the levee system would not be affected because most of 
those resources are located outside of the floodway, and away from 
potential levee footprint expansion areas. Only irrigation canals and 
minor irrigation structures, such as weir gates and standpipes, are 
located within or near the levee service corridor where footprint 
expansion would take place; irrigation canals and nearly all irrigation 
structures would be retained in their current condition.
Water Resources
    Improvements to the levee system would increase flood containment 
capacity to control the design flood event with a negligible increase 
in water surface elevation. Levee footprint expansion would not affect 
water resources.
Land Use
    Footprint levee expansion, where required, would take place 
completely within the existing floodway and along the levee service 
corridor. No urban or agricultural lands would be affected. Impacts to 
natural resources conservation areas would be limited to grassland 
areas.
Community Resources
    In terms of socioeconomic resources, the influx of federal funds 
into Hidalgo, Cameron, and Willacy Counties from the levee improvement 
project would have a positive but minor local economic impact. The 
impact would be limited to the construction period, and represent less 
than 1 percent of the annual county employment, income and sales 
values. No adverse impacts to disproportionately high minority and low-
income populations were identified for construction activities. A 
moderate increase in utilization of public roads would be required 
during construction; a temporary increase in access road use would be 
required for equipment mobilization to staging areas.
Environmental Health Issues
    Estimated air emissions of five criteria pollutants during 
construction represent less than 1.1 percent of the annual emissions 
inventory of Hidalgo, Cameron, and Willacy Counties. There would be a 
moderate increase in ambient noise levels due to construction 
activities. No long-term and regular exposure is expected above noise 
threshold values. A database search indicated that no waste storage and 
disposal sites were within the proposed Main and North Floodway Levee 
Project area, and none would affect, or be affected, by the levee 
improvement project.
Best Management Practices
    When warranted due to engineering considerations, or for protection 
of biological or cultural resources, the need for levee footprint 
expansion would be eliminated by levee slope adjustment. Best 
management practices during construction would include development of a 
storm water pollution prevention plan to avoid impacts to receiving 
waters, and use of sediment barriers and soil wetting to minimize 
erosion and dust.
    To protect vegetation cover, both the modified levee and 
construction corridor would be re-vegetated with native herbaceous 
species. To protect wildlife, construction activities would be 
scheduled to occur, to the extent possible, outside the March to August 
bird migratory season.

Availability

    Single hard copies of the Final Environmental Assessment and 
Finding of No Significant Impact may be

[[Page 67756]]

obtained by request at the above address. Electronic copies may also be 
obtained from the USIBWC Home Page at http://www.ibwc.state.gov.

    Dated: November 20, 2007.
Allen Thomas,
Attorney Advisor.
[FR Doc. E7-23029 Filed 11-29-07; 8:45 am]
BILLING CODE 7010-01-P