05-22089. United States Section; Notice of Availability of a Final Environmental Assessment and Finding of No Significant Impact for Alternatives for Improved Flood Control of the Hidalgo Protective Levee System, in the Lower Rio Grande Flood ...

AGENCY:

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

ACTION:

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

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 USIBWC's 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 Final Environmental Assessment and Finding of No Significant Impact for Alternatives for Improved Flood Control of the Hidalgo Protective Levee System, in the Lower Rio Grande Flood Control Project, located in Hidalgo County, Texas are available. A notice of finding of no significant impact dated June 30, 2005, provided a thirty (30) day comment period before making the finding final. The Notice was published in the Federal Register on July 8, 2005 (70 FR 39527).

FOR FURTHER INFORMATION CONTACT:

Gilbert Anaya, Environmental Management Division; United States Section, International Boundary and Water Commission; 4171 N. Mesa, C-100; El Paso, Texas 79902. Telephone: [phone], e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Proposed Action

The USIBWC is considering alternatives to raise the Hidalgo Protective Levee System. The proposed action will take place in two construction phases, each covering separate geographic reaches of the Hidalgo Protective Levee System. Phase 1 encompasses the upstream 3.3-mile reach of the levee system, from the Hidalgo Levee junction with the LRGFCP Main Floodway, to the west margin of the Hidalgo-Reynosa International Bridge. Phase 2, for subsequent implementation, covers the 1.2-mile downstream reach starting at the international bridge. The phased construction approach responds to the likely availability of early funding for Phase 1, the upstream reach of the project.

In-place increase of levee height under the Phase 1 Footprint Expansion Alternative is the Proposed Action for Phase 1 of the project. This alternative will increase flood containment capacity by raising the height of the existing compacted earthen levee to meet the freeboard requirement indicated by the hydraulic model. Soil borrow easements will be used to secure levee material.

Partial rerouting of the 1.2-mile downstream reach of the levee system under the Partial Levee Rerouting Alternative is the Phase 2 Proposed Action. Levee rerouting is proposed to eliminate the need for construction of a floodwall in front of the Hidalgo Historic Pumphouse, a resource included in the National Register of Historic Places (NRHP). A new levee segment, approximately 0.7 mile in length, will be built along the south margin of the pumphouse intake channel, and the channel will be crossed to tie the new structure to the existing levee system. Floodwall placement will be required along the Hidalgo-Reynosa International Bridge.

Alternatives under consideration to improve the Hidalgo Protective Levee System will expand the levee footprint by lateral extension of the structure. Levee footprint increases toward the riverside could potentially extend into floodplain areas designated by the U.S. Fish and Wildlife Service as part of the Lower Rio Grande Valley (LRGV) National Wildlife Refuge System. Footprint increases toward the levee landside could extend beyond the USIBWC right-of-way.

Alternatives Considered

Phase 1 Alternative

A Phase 1 No Action Alternative was evaluated for the 3.3-mile upstream reach of the levee system. This alternative would retain the existing configuration of the Hidalgo Protective Levee 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 will be insufficient to fully control Rio Grande flooding with risks to personal safety and property.

Phase 2 Alternatives

A Phase 2 No Action Alternative and two action alternatives to the Proposed Action were evaluated for Phase 2 of the levee system improvement project: the Footprint Expansion Alternative, and the No-Footprint Expansion Alternative.

Under the Phase 2 No Action Alternative, the existing Hidalgo Protective Levee System would be retained in its current configuration along levee miles 3.3 to 4.5.

Under the Phase 2 Footprint Expansion Alternative, height of the existing levee would be increased with the associated lateral expansion of the footprint. Placement of floodwalls would be required at two segments where retaining walls are currently present: along the two spans of the Hidalgo-Reynosa International Bridge, and along the Hidalgo Historic Pumphouse.

Under the No-Footprint Expansion Alternative, a mechanically stabilized earth structure along the levee crown would eliminate the need for an expanded earthen levee and footprint expansion. Floodwall placement would be required both at the Hidalgo Historic Pumphouse and along the two spans of the Hidalgo-Reynosa International Bridge.

Availability

Single hard copies of the Final Environmental Assessment and final 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 24, 2005.

Susan Daniel,

General Counsel.