[Federal Register Volume 72, Number 4 (Monday, January 8, 2007)]
[Notices]
[Pages 797-798]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-46]


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INTERNATIONAL BOUNDARY AND WATER COMMISSION, UNITED STATES AND MEXICO, 
AND UNITED STATES SECTION


Notice of Availability of a Draft Environmental Assessment and 
Finding of No Significant Impact for Improvements to the Lateral A/
Retamal Dike Levee System, in the Lower Rio Grande Flood Control 
Project, located in Hidalgo County, TX

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

ACTION: Notice of Availability of Draft Environmental Assessment (EA) 
and Draft 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 that the Draft Environmental Assessment and FONSI 
for Improvements to the Lateral A/Retamal Dike Levee System, in the 
Lower Rio Grande Flood Control Project, located in Hidalgo County, 
Texas, are available.

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: Comments on the Draft EA and Draft FONSI will be accepted 
through February 5, 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 U.S. Fish and Wildlife Service 
(USFWS), prepared this Draft Environmental Assessment (Draft EA) for 
the proposed action of raising the Lateral A/Retamal Dike Levee System 
located in Hidalgo County, Texas to improve flood control. 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 
Lateral A/Retamal Dike Levee System extends approximately 14 miles, 
from the Carlson Settling Basin to Retamal Diversion Dam.

Proposed Action

    The Proposed Action would increase the flood containment capacity 
of the Lateral A/Retamal Dike System to meet the 3-foot freeboard 
design criterion for flood protection. Throughout the approximately 
11.5-mile Lateral A segment, height increases between 1.5 and 4 feet 
are typically needed to reach the design freeboard value. For the 3.5-
mile Retamal Dike segment, typical increases in levee height range from 
0 to 2 feet. The increase in levee height will result in an expansion 
to the levee footprint by lateral extension of the structure. 
Structural improvements, such as a slurry cutoff barrier or a riverside 
impermeable liner, may be required for some levee segments where 
seepage is a potential problem.

Alternatives to the Proposed Action

    A No Action Alternative was evaluated for the Lateral A/Retamal 
Dike System. This alternative will retain the existing configuration of 
the system, 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 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 Lateral A/Retamal Dike 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.

[[Page 798]]

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 Lateral A/Retamal Dike 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 Lateral A/Retamal Dike Levee would require 
vegetation removal. The approximate removal is 151 acres of herbaceous 
vegetation, 3 acres of Mesquite-Acacia woodland, and 8 acres of Texas 
Ebony-Anacua forest. Given its small extent, woodland removal would 
have a minimum impact on wildlife habitat. No significant effects are 
anticipated for any of the 25 threatened and endangered species with 
potential habitat near the right-of-way (ROW). None of 17 wetlands 
located within the ROW are located within the construction corridor and 
would be impacted by the potential levee expansion. Indirect impacts to 
wetlands near the corridor will be avoided, as required, by 
modification of the levee expansion alignment.
Cultural Resources
    Improvements to the Lateral A/Retamal Levee system may adversely 
affect known archaeological resources, by mechanical excavation or by 
burial under the expanded levee footprint. Resources potentially 
affected include nine areas with a high probability to contain historic 
or prehistoric archaeological materials, and two known archaeological 
sites. Historic-age resources would also be affected, primarily 
structures associated with irrigation canals along the levee. These 
resources are the levee, canals, weir gates, standpipes, bridges, and 
residential structures. Several of the historic-age resources 
identified are located landside of the levee, across irrigation canals, 
and will not be adversely affected or minimally affected.
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 bodies.
Land Use
    The expansion would take place almost completely within the ROW. 
Removal of approximately 3 acres of woodlands from natural resources 
management areas would be required. Levee expansion would affect less 
than 1 acre of active agricultural areas. Two irrigation canals along 
the levee would be temporarily affected by construction activities. 
There is a minimum potential for impacts on urban areas since no 
residential developments are located near the levee.
Community Resources
    In terms of socioeconomic resources, the influx of federal funds 
into Hidalgo County from the levee improvement would have a positive 
local economic impact limited to the construction period; the impact 
would 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. Moderate utilization of public roads is 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 0.7 percent of the Hidalgo County 
annual emissions inventory. There would be a moderate increase in 
ambient noise levels due to excavation and fill activities. No long-
term and regular exposure is expected above noise threshold values. A 
database search identified no waste storage or disposal sites within 
the expanded levee footprint and its vicinity.
Best Management Practices and Mitigation
    Engineering design measures will be used, including optimization of 
the levee expansion alignment to avoid impacts on wooded vegetation, 
wetlands, and other natural resources. Riverside expansion will be used 
for a majority of the Lateral A/Retamal Dike Levee System. During 
construction, best management practices will include development of a 
storm water pollution prevention plan to minimize impacts of receiving 
waters, and use of sediment barriers and soil wetting to minimize 
erosion.
    To protect vegetation, the construction corridor may be re-
vegetated with herbaceous or woody vegetation, as agreed with the 
natural resources management organization where the corridor is 
located. Final surveys prior to the start of the project would 
determine the types and amounts of vegetation to be removed, and 
separation between construction corridor and boundaries of wetlands. To 
protect wildlife, construction activities will be scheduled to occur, 
to the extent possible, outside the bird migratory season.
    If buried cultural materials are encountered during construction, 
work would cease and notification given to the State Historic 
Preservation Officer. Mitigation actions recommended by the Texas 
Historical Commission (THC) for potential impacts to historical or 
archaeological resources will be specified in a Memorandum of Agreement 
between THC and the USIBWC.

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 http://www.ibwc.state.gov.

    Dated: December 29, 2006.
Allen Thomas,
Attorney Advisor.
 [FR Doc. E7-46 Filed 1-5-07; 8:45 am]
BILLING CODE 7010-01-P