E9-5065. United States Section; Notice of Availability of a Final Environmental Assessment and Finding of No Significant Impact for Improvements to the Rio Grande Rectification Project in El Paso and Hudspeth Counties, TX

AGENCY:

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

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 (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 Rio Grande Rectification Project (RGRP) located in El Paso and Hudspeth Counties, Texas are available.

FOR FURTHER INFORMATION CONTACT:

Lisa Santana, 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].

DATES:

The Final EA and FONSI will be available March 13, 2009.

SUPPLEMENTARY INFORMATION:

Background

The RGRP is a flood control and water delivery project completed in 1938 along the Rio Grande in El Paso and Hudspeth Counties, Texas. The RGRP, extending approximately 91 miles from El Paso to Fort Quitman, consists of a flood control levee system along the United States and Mexico margins of the Rio Grande, a maintained floodway enclosed by the levee system, and a dredged river channel.

The USIBWC identified the RGRP as a priority area to improve flood containment and restore normal flow capacity of the river channel. Flood control is the core mission of the RGRP whose economic benefits have been estimated at over $140 million in terms of protection of residential, industrial, and commercial structures, and agricultural use. The RGRP was also built to ensure efficient delivery of water for irrigation and other uses in the United States and Mexico. A need has been identified to restore normal flow capacity of the river, reduced by sediment deposition, to improve irrigation water delivery and comply with existing agreements between the two countries.

Proposed Action

Alternatives to the Proposed Action

The proposed action to improve functionality of the RGRP has two components, raising the levee system along various river segments to meet current flood control requirements, and dredging the river channel to restore normal flow capacity.

To increase flood containment capacity, fill material would be added on top of the levee system to bring height to its original design specifications, or to meet current flood control requirements. Various sections of the RGRP levee system along the United States margin of the Rio Grande would be raised up to 4 feet, using compatible fill material obtained from commercial sources. Height increase would result in expansion of the levee footprint, up to a maximum of 12 feet on each side of the levee. The expansion would take place along the levee service corridor currently utilized for levee maintenance, and entirely within the RGRP right-of-way. Excavation outside the levee structure is not an anticipated need.

Normal flow capacity of the river, reduced by sediment deposition, would be restored to ensure efficient water delivery and comply with existing agreements between the two countries. Dredging to be conducted by the USIBWC would cover three Rio Grande segments with an approximate combined length of 45 miles within the RGRP.

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 (EA). The USIBWC completed an EA of the potential environmental consequences of improvements to the flood control and water delivery capabilities of the RGRP. The EA, which supports this Finding of No Significant Impact, evaluated the No Action Alternative and Proposed Action.

Potential Environmental Impacts

No Action Alternative

The No Action Alternative was evaluated as the single alternative action to the Proposed Action. The No Action Alternative would retain current conditions of the RGRP in terms of the levee system configuration and sediment deposition in the river channel, with no impacts to biological and cultural resources, land use, or environmental health issues. In terms of flood protection, however, current containment capacity under the No Action Alternative may be insufficient in fully controlling the Rio Grande flooding under severe storm events, with associated risks to personal safety and property. Non-implementation of dredging operations would be detrimental to extensive irrigated areas served by the RGRP due to inefficiency in water deliveries, and would fail to comply with existing boundary agreements between the two countries.

Proposed Action

Biological Resources

Placement of fill material on the levee would affect herbaceous vegetation present on footprint expansion locations and slope of the levee structure. All expansion would take place along the current levee service corridor, limiting vegetation removal to currently managed areas; this plant cover is expected to rapidly re-establish after project completion.

No significant effects are anticipated on wildlife habitat in the vicinity of the levee system. In areas requiring levee footprint expansion, impacts on vegetation would be limited to non-native managed salt cedar habitats and managed old-field habitats along the levee that are of very limited value as wildlife habitat. Levee expansion may remove some habitat for the Species of Concern Burrowing Owl, but levee expansion would occur outside the breeding season of the owls to reduce impacts. Further, the levee expansion will not be in conflict with the burrowing owl management plan. No jurisdictional wetlands are located within the potential levee expansion area, potential bed down areas or disposal sites.

Dredging operations would remove vegetation along some sections of the riverbanks. The river does not contain wetlands, and the vegetation communities along the river are expected to rapidly re-establish after project completion. Dredging is not expected to have an effect on wildlife, including T&E species. Sediment disposal areas are outside the floodway, and sediment disposal would not affect sensitive habitats or wetlands.

Levee expansion would not affect aquatic resources of the Rio Grande. Dredging operations would temporarily affect aquatic habitats and resources; however, dredging operations would occur during low- or no-flow conditions. Therefore, aquatic habitats will be minimally affected by dredging operations.

Levee expansion and dredging operations will not affect unique or sensitive areas, including the Rio Bosque Wetlands Park.

Cultural Resources

Levee footprint expansion would take place along the current levee service corridor. The use of heavy equipment in the floodway and staging areas (including equipment yards and soil storage areas) to add and move soil material for levee expansion may cause soil disturbance several inches deep in the service corridor. Based on the results of previous trenching for geoarchaeological investigations in the project area, the upper 10 to 20 inches (25 to 50 centimeters) of the floodway exhibit evidence of leveling and mixing due to disturbances such as the original construction of the RGRP levee in the 1930s and ongoing floodway maintenance. Archaeological resources occurring up to this depth likely lack physical integrity and context and would most likely not be eligible for the National Register of Historic Places (NRHP). Levee footprint expansion may cap more deeply buried, intact archaeological resources with soil and gravel and could result in either a potentially beneficial or a potentially adverse effect to these resources. Architectural resources may be adversely affected by expansion of the levee footprint. Potential effects include vibration and ground disturbance from the use of heavy equipment during construction as well as effects caused by alterations to the levee itself; however, the increased height of the levee is not expected to change the flow of water to or from architectural resources. Under NEPA, there will be no significant impacts (i.e., “unresolvable” adverse effects under NHPA) to cultural resources because archaeological resources in the APE will be identified and architectural resources will be evaluated for NRHP eligibility prior to implementation of levee footprint expansion. Native American resources, including river access and sensitive Native American plant resources, may be altered by the levee improvements; consultation with the Native American tribes will assist in scheduling construction during times when the river and plants are not being used for ceremonial purposes.

There are no anticipated effects of dredging on archaeological resources. Dredging within the river channel will occur to a depth of 3 feet and simply remove silt deposited since previous dredging was conducted. Movement of heavy equipment used to dredge material from the river may disturb soil several inches deep in the floodway along the river and in staging areas, but no NRHP-eligible resources are expected to occur at that depth. If architectural resources (e.g., lateral drain abutments) are in the areas of dredging operations, they would be avoided and would not be affected. Native American resources, including river access and sensitive Native American plant resources, could be adversely affected by dredging operations.

Intensive archaeological and architectural surveys to identify and evaluate cultural resources in the project area will be conducted in accordance with Texas State Historic Preservation Office (SHPO), (Texas Historical Commission [THC]), requirements. Cultural resources in the project area may include archaeological sites as well as levee-related resources, irrigation-related resources, roadway bridges, and culverts.

Water Resources

Improvements to the RGRP levee would increase flood containment capacity with a negligible increase in floodwater surface elevation. Levee footprint expansion would not affect water supply or management, agricultural water uses, or water quality.

Dredging operations would improve water flow within the river. Water supply and water management would be improved by making delivery of irrigation water more efficient. Dredging operations would temporarily affect water quality, but effects would attenuate with distance and would subside at the conclusion of the operations. Dredging operations would be scheduled to occur during low flow or no flow conditions to minimize impacts to water quality.

Land Use

Footprint levee expansion, where required, would take place completely within the existing right-of-way and along the levee service corridor. No urban or agricultural lands would be affected. Dredging operations, including equipment staging, would occur within the existing USIBWC right-of way outside the floodway. Sediment disposal would occur at pre-selected sites along the levee service corridor, outside the floodway, or on farmland by request. Dredged sediment disposed of on farmland could be used as a soil amendment and improve drainage in agricultural fields.

Community Resources

Residents and property along the RGRP would benefit from the continued flood protection. The influx of federal funds into El Paso and Hudspeth Counties from levee improvements and dredging operations would also have a positive local economic impact, largely limited to the construction period. The benefit would be small for El Paso County given its large economic base, less than 1% of the annual county employment, income and sales values. The effect would be more substantial in Hudspeth County because of its small population. No adverse impacts to disproportionately high minority and low-income populations were identified for construction activities. Moderate utilization of public roads would be required during construction, with a temporary increase in access road for equipment mobilization to staging areas.

Environmental Health Issues

Estimated air emissions of five criteria pollutants during construction would be discontinuous and represent less than 0.3 percent of the annual emissions inventory for El Paso County, and less than 1.5 percent for Hudspeth County. There would be a moderate increase in ambient noise levels due to construction activities. Neither long-term nor regular exposure is expected above noise threshold values. A database search indicated that no waste storage and disposal sites were within proposed work areas, and none would affect, or be affected, by the proposed RGRP improvements.

Best Management Practices

Best management practices and mitigation measures would be implemented as part of the Proposed Action to minimize the potential for impacts to natural resources, and mitigation measures used compensate for potential adverse effects. Best managements practices during construction would include use of sediment barriers and soil wetting to minimize erosion and dust.

Levee expansion alignment would be optimized, to the extent possible, to avoid impacts to riparian native wooded vegetation, including mature woody trees, if present. The project would comply with U.S. Environmental Protection Agency (USEPA) requirements for construction and equipment staging areas to avoid impacts on water quality and other aquatic resources. Continued coordination with the Texas Parks and Wildlife Department (TPWD) will be necessary for protection of burrowing owl nesting locations, including schedule modification of levee improvement operations. To protect wildlife, construction activities would be scheduled to occur, to the extent possible, outside the March 1st to August 31st bird migratory season as required by the United States Migratory Bird Treaty Act.

Availability: The Final Environmental Assessment and Finding of No Significant Impact are available at the USIBWC homepage at http://www.ibwc.state.gov/​Organization/​Environmental/​reports_​studies.html.

Dated: March 6, 2009.

Robert McCarthy,

General Counsel.