E7-25118. United States Section; Notice of Availability of a Final Environmental Assessment and Final Finding of No Significant Impact for Flood Control Improvements to the Rio Grande Canalization Project Levee System, El Paso County, TX, and Sierra ...

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).

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 Flood Control Improvements to the Rio Grande Canalization Project located within El Paso County, Texas and Sierra and Dona Ana Counties, New Mexico.

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: [phone]; e-mail: [e-mail].

SUPPLEMENTARY INFORMATION:

Background

The Rio Grande Canalization Project was authorized by the Act of June 4, 1936, 49 Stat. 1463, Public Law No. 648 to facilitate compliance with the Convention concluded with Mexico on May 21, 1906 (TS 455), providing for the equitable division of waters of the Rio Grande, and to properly regulate and control the water supply for use in the two countries. The Act authorized the construction, operation, and maintenance of the project in accordance with the plan in the Engineering Report of December 14, 1935.

Proposed Action

The Proposed Action would increase the flood containment capacity of the Rio Grande Canalization Project Levee System by raising the elevation of a number of levee segments for improved flood protection. Fill material, obtained from commercial sources would be added to the existing levee to meet the 3 foot freeboard criterion. Typical height increases in improvement areas would range from 1 to 4 feet. Improvements greater than 2 feet would require expansion of the existing levee footprint. In some locations, up to 4 feet of fill material would be added, extending the levee footprint up to a maximum of 24 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, adjustments in levee slope would be made to eliminate the need for levee footprint expansion, when required by engineering considerations or for protection of resources.

Alternatives to the Proposed Action

A No Action Alternative was evaluated for the flood control improvements to the Rio Grande Canalization Project Levee System. This alternative would retain the existing configuration of the system, 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 segments of the Rio Grande Canalization Project Levee System to meet current requirements for flood control. The EA, which supports the 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 Rio Grande Rectification Project Levee System, with no impacts to biological and cultural resources, water resources, land use, community resources, and 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. The USIBWC will not be able to certify the levee system segments, that are being targeted for improvements, as meeting Federal Emergency Management Act (FEMA) requirements.

Proposed Action

Biological Resources

Improvements to the levee system would entail clearing and placement of fill material on the existing levees. Vegetation would be impacted along the levee slopes and at locations where levee footprint expansion is required (fill greater than 2 feet). Levee expansion, if required, would take place along the current levee service corridor, limiting vegetation removal to low quality invasive plant species along the levee slopes. Avoidance measures would be implemented to protect resources, as needed.

No significant effects are anticipated on wildlife habitat in the vicinity of the levee system, including potential habitat for threatened and endangered species. In areas requiring levee footprint expansion, no riparian woodland communities would be impacted; impacts on vegetation would be limited to low quality vegetation along the levee slopes, of very limited value as wildlife habitat.

Cultural Resources

Improvements to the 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.

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

Levee improvements would occur on existing levee structures. Footprint levee expansion, where required, would take place completely within the existing levee footprint, including the existing service corridor, and remain within USIBWC right-of-way (ROW). There is minimal potential for impacts to urban or agricultural lands since the majority of the work will take place on USIBWC ROW. The majority of the existing river trails would not be impacted, except for those segments that have been constructed on top of the levee and are within the areas targeted for improvements.

Community Resources

In terms of socioeconomic resources, the influx of federal funds into El Paso, Dona Ana, and Sierra Counties from the levee improvement project would have a positive but minor local economic impact. 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 and material shipments.

Environmental Health Issues

Improvements to the levee system would have minimal impact to air quality through construction activities. Air emissions during construction would be limited to heavy equipment operation during normal working hours. 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.

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 use of sediment barriers and soil wetting to minimize erosion and dust. To protect riparian woody vegetation, avoidance measures will be implemented. 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 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 19, 2007.

Susan E. Daniel,

General Counsel.