[Federal Register: October 24, 2006 (Volume 71, Number 205)]
[Notices]
[Page 62295-62297]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr24oc06-78]
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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: gilbertanaya@ibwc.state.gov.
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 http://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