J.09_Rectification_FinalEA_Mar2009.pdf

Final Environmental Assessment Improvements to the

Rio Grande Rectification Project

Lead Agency:

United States Section, International Boundary and

Water Commission El Paso, Texas

March 2009

COVER SHEET

FINAL ENVIRONMENTAL ASSESSMENT

AND

FINDING OF NO SIGNIFICANT IMPACT

IMPROVEMENTS TO THE RIO GRANDE

RECTIFICATION PROJECT

Lead Agency: United States Section, International Boundary and Water Commission (USIBWC)

Proposed Action: Improvements to the Rio Grande Rectification Project (RGRP) to increase flood protection, and to restore normal flow capacity of the river channel.

Report Designation: Environmental Assessment

Abstract: The RGRP is a flood control and water delivery project completed in 1938 along the Rio Grande in west Texas. 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 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, to retain current slope design values. 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.

In addition to flood control, the RGRP was constructed to efficiently deliver water for irrigation and other uses, both in Mexico and in the United States. 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.

This Environmental Assessment assesses potential impacts of the Proposed Action and the No Action Alternative. Both alternatives are evaluated in terms of potential impacts on water, natural, cultural, and other resources, along with adopted mitigation measures, when applicable. A Finding of No Significant Impact was issued for the Proposed Action based on a review of the facts and analyses contained in the Environmental Assessment.

FINDING OF NO SIGNIFICANT IMPACT

IMPROVEMENTS TO THE RIO GRANDE RECTIFICATION PROJECT

IN EL PASO AND HUDSPETH COUNTIES, TEXAS

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

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

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.

FINAL ENVIRONMENTAL ASSESSMENT

IMPROVEMENTS TO THE RIO GRANDE RECTIFICATION PROJECT

Lead Agency:

UNITED STATES SECTION,

INTERNATIONAL BOUNDARY AND WATER COMMISSION

UNITED STATES AND MEXICO

Technical Support:

PPaarrssoonnss

8000 Centre Park Dr., Suite 200 Austin, Texas 78754

MARCH 2009

Improvements to the Rio Grande Rectification Project Final Environmental Assessment Contents i USIBWC

TABLE OF CONTENTS

LIST OF TABLES................................................................................................................... iv LIST OF FIGURES................................................................................................................. iv ACRONYMS AND ABBREVIATIONS ................................................................................ v

SECTION 1 PURPOSE OF AND NEED FOR THE PROPOSED ACTION .................1-1

1.1 Purpose of and Need for Action ............................................................................1-1

1.2 USIBWC Authority ...............................................................................................1-2

1.3 Scope of the Environmental Review .....................................................................1-5

1.3.1 Regulatory Compliance Framework.............................................................1-5

1.3.2 Resource Areas Evaluated............................................................................1-6

1.4 Environmental Coordination and Compliance Analysis .......................................1-6

1.5 Organization of the Environmental Assessment ...................................................1-8

SECTION 2 DESCRIPTION OF ALTERNATIVES ........................................................2-1

2.1 No Action Alternative ...........................................................................................2-1

2.1.1 Levee System Maintenance..........................................................................2-1

2.1.2 Floodway Maintenance ................................................................................2-2

2.1.3 River Channel Maintenance .........................................................................2-2

2.2 Proposed Action ....................................................................................................2-3

2.2.1 Levee Improvements ....................................................................................2-3

2.2.2 Dredging of River Channel ..........................................................................2-5

2.3 Other Actions With Potential Cumulative Impacts ...............................................2-7

2.4 Summary Comparison of Environmental Consequences of the Alternatives .......2-7

2.4.1 No Action Alternative ..................................................................................2-7

2.4.2 Proposed Action ...........................................................................................2-7

SECTION 3 AFFECTED ENVIRONMENT......................................................................3-1

3.1 Biological Resources .............................................................................................3-1

3.1.1 Vegetation.....................................................................................................3-1

3.1.2 Wildlife.........................................................................................................3-2

3.1.3 Threatened and Endangered Species ............................................................3-2

3.1.4 Wetlands .......................................................................................................3-3

3.1.5 Aquatic Habitats ...........................................................................................3-3

3.1.6 Unique or Sensitive Areas ............................................................................3-4

3.2 Cultural Resources.................................................................................................3-4

3.2.1 Affected Environment ..................................................................................3-5

3.2.2 Previous Cultural Resources Studies............................................................3-5 ii USIBWC

3.2.3 Archaeological Resources ............................................................................3-6

3.2.4 Architectural Resources................................................................................3-6

3.2.5 Native American Resources .........................................................................3-8

3.3 Water Resources....................................................................................................3-9

3.3.1 Flood Control................................................................................................3-9

3.3.2 Water Supply and Water Management.........................................................3-9

3.3.3 Agricultural Water Use.................................................................................3-9

3.3.4 Water Quality .............................................................................................3-10

3.4 Land Use..............................................................................................................3-10

3.4.1 Urban Areas................................................................................................3-11

3.4.2 Agricultural Land .......................................................................................3-11

3.5 Community Resources.........................................................................................3-12

3.5.1 Socioeconomics ..........................................................................................3-12

3.5.2 Environmental Justice ................................................................................3-13

3.5.3 Transportation.............................................................................................3-14

3.6 Environmental Health..........................................................................................3-14

3.6.1 Air Quality..................................................................................................3-14

3.6.2 Noise...........................................................................................................3-15

3.6.3 Public Health and Environmental Hazards.................................................3-16

SECTION 4 ENVIRONMENTAL CONSEQUENCES.....................................................4-1

4.1 Biological Resources .............................................................................................4-1

4.1.1 Vegetation.....................................................................................................4-1

4.1.2 Wildlife.........................................................................................................4-2

4.1.3 Threatened and Endangered Species ............................................................4-2

4.1.4 Wetlands .......................................................................................................4-3

4.1.5 Aquatic Habitats ...........................................................................................4-4

4.1.6 Unique or Sensitive Habitats ........................................................................4-4

4.2 Cultural Resources.................................................................................................4-5

4.2.1 Archaeological Resources ............................................................................4-5

4.2.2 Architectural Resources................................................................................4-7

4.2.3 Native American Resources .........................................................................4-8

4.3 Water Resources....................................................................................................4-9

4.3.1 Flood Control................................................................................................4-9

4.3.2 Water Supply and Water Management.......................................................4-10

4.3.3 Agricultural Water Use...............................................................................4-10 iii USIBWC

4.3.4 Water Quality .............................................................................................4-11

4.4 Land Use..............................................................................................................4-11

4.4.1 Urban Areas................................................................................................4-11

4.4.2 Agricultural Areas ......................................................................................4-11

4.5 Community Resources.........................................................................................4-12

4.5.1 Socioeconomics ..........................................................................................4-12

4.5.2 Environmental Justice ................................................................................4-14

4.5.3 Transportation.............................................................................................4-15

4.6 Environmental Health..........................................................................................4-16

4.6.1 Air Quality..................................................................................................4-16

4.6.2 Noise...........................................................................................................4-17

4.6.3 Public Health and Environmental Hazards.................................................4-18

4.7 Indirect and Cumulative Impacts.........................................................................4-18

SECTION 5 BEST MANAGEMENT PRACTICES AND MITIGATION

MEASURES ....................................................................................................5-1

5.1 Engineering Measures ...........................................................................................5-1

5.2 Natural Resources..................................................................................................5-2

5.3 Cultural Resources.................................................................................................5-2

SECTION 6 ENVIRONMENTAL COMPLIANCE AND COORDINATION...............6-1

6.1 Consultation...........................................................................................................6-1

6.1.1 Draft EA Distribution ...................................................................................6-1

6.1.2 Draft EA Comments and Responses ............................................................6-2

6.2 List of Contributors ...............................................................................................6-2 SECTION 7 REFERENCES ................................................................................................7-1

APPENDICES

Appendix A Detailed Maps of Potential Improvement Areas Appendix B Biological Evaluation Update for the RGRP Appendix C Draft EA Review Correspondence iv USIBWC

LIST OF TABLES

Table 1.1 Estimated Economic Benefits of the RGRP Operation........................................1-2 Table 1.2 Summary of Environmental Coordination and Compliance by Resource Area...1-7 Table 2.1 Extent of Potential Levee Footprint Expansion Downstream from Riverside

Dam ......................................................................................................................2-5 Table 2.2 Sediment Removal Locations by USIBWC and Estimated Removal Volume ....2-6 Table 2.3 Estimated Sediment Disposal Needs ....................................................................2-7 Table 2.4 Summary of Environmental Impacts of Proposed Levee Improvements and

Dredging Activities in the RGRP .........................................................................2-8 Table 3.1 Architectural Resources in the Area of Potential Effect ......................................3-7 Table 3.2 Native American Groups Identified for RGRP ....................................................3-8 Table 3.3 Population Growth in El Paso and Hudspeth Counties Adjacent to the

RGRP..................................................................................................................3-12 Table 3.4 Estimated Total Employment for El Paso and Hudspeth Counties....................3-13 Table 3.5 Minority Populations and Poverty Rates in the RGRP Area..............................3-14 Table 4.1 Potential Economic Impacts of Improvements to the RGRP Levee in El Paso

County ................................................................................................................4-13 Table 4.2 Potential Economic Impacts of Improvements to the RGRP Levee in Hudspeth

County ................................................................................................................4-14 Table 4.3 Potential Air Emissions of RGRP Improvements ..............................................4-17 Table 6.1 Environmental Assessment Preparation Technical Team ....................................6-2

LIST OF FIGURES

Figure 1 Rio Grande Rectification Project – Upper Reach.................................................1-3 Figure 2 Rio Grande Rectification Project – Lower Reach ................................................1-4 Figure 3 Typical Cross-Section of a Levee, Illustrating Footprint Expansion ...................2-4

Final Environmental Assessment Acronyms and Abbreviations v USIBWC

ACRONYMS AND ABBREVIATIONS

AIRFA American Indian Religious Freedom Act APE Area of Potential Effect

AQCR Air Quality Control Regions BMP best management practice CFR Code of Federal Regulations cfs cubic feet per second dBA average-weighted sound level in decibels E.O. Executive Order

EA Environmental Assessment EIS environmental impact statement

FEMA Federal Emergency Management Agency HAER Historic American Engineering Record IBWC International Boundary and Water Commission

MxIBWC Mexican Section, International Boundary and Water Commission NAAQS National Ambient Air Quality Standards

NAGPRA Native American Graves Protection and Repatriation Act NEPA National Environmental Policy Act NHPA National Historic Preservation Act NRCS Natural Resources Conservation Service NRHP National Register of Historic Places

O&M operation and maintenance PM10 particulate matter greater than 10 micrometers in size

Programmatic EIS Programmatic Environmental Impact Statement RCRA Resource Conservation and Recovery Act RGRP Rio Grande Rectification Project ROW right-of-way

SHPO State Historic Preservation Office T&E threatened and endangered

TCEQ Texas Commission on Environmental Quality THC Texas Historic Commission

TPWD Texas Parks and Wildlife Department USACE U.S. Army Corps of Engineers

USBP U.S. Border Patrol USEPA United States Environmental Protection Agency USFWS U.S. Fish and Wildlife Service

USIBWC United States Section, International Boundary and Water Commission yd3 cubic yards

Final Environmental Assessment Purpose of and Need for the Proposed Action

1-1 USIBWC

SECTION 1

PURPOSE OF AND NEED FOR THE PROPOSED ACTION

The United States Section, International Boundary and Water Commission (USIBWC) prepared this Environmental Assessment (EA) for proposed improvements to the Rio Grande Rectification Project (RGRP), located in El Paso and Hudspeth Counties, Texas. The RGRP, extending approximately 91 miles from El Paso to Fort Quitman, Texas, 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 proposed action has two components, raising the height of the levee system in the United States margin of the RGRP to increase its flood containment capacity, and dredging three segments of the river channel to restore normal flow capacity. Figures 1 and 2 show the layout of the upper and lower reaches of the RGRP, along with main geographic features and river-mile markers used as a reference throughout this document.

This EA has been tiered-off from a Programmatic Environmental Impact Statement (Programmatic EIS) recently completed by the USIBWC for long-term improvements to Rio Grande flood control projects operated along the Texas-Mexico border (USIBWC 2008a).

Descriptions of environmental conditions along the RGRP presented in this EA are summaries of more detailed information provided in the Programmatic EIS; these descriptions are supplemented in the areas of biological and cultural resources with data from a field evaluation conducted in support of the EA preparation.

Section 1 of the EA discusses the purpose of and need for the Proposed Action; the authority of the USIBWC to conduct the project as part of its mission; the scope of the environmental review; a summary of environmental compliance requirements; and the organization of this document. Subsequent sections discuss in detail the Proposed Action, environmental conditions in the RGRP area, potential impacts identified, and adopted best management practices and mitigation actions.

1.1 PURPOSE OF AND NEED FOR ACTION

The USIBWC identified the RGRP as a priority area to improve flood containment and restore normal flow capacity of the river channel. Flood protection, the core mission of the RGRP, represents a sizable federal investment for protection and enhancement of economic conditions along the Rio Grande. A USIBWC-sponsored study (Sturdivant, et al. 2004) evaluated economic benefits derived from the flood control mission of the RGRP. The study concluded that the economic benefit is approximately $139 million for protection of residential, industrial, and commercial structures, and an additional $1.25 million was estimated for protection of agricultural use. In addition to the baseline benefits for protection of structures, nearly $69 million in damage protection was calculated for loss of roads and utilities and emergency response and recovery. Table 1.1 shows the calculated baseline economic benefits of the RGRP.

1-2 USIBWC

Table 1.1 Estimated Economic Benefits of the RGRP Operation

Category 1 Estimated

Area (acres)

% of Total Area

Estimated Damages

($ per acre) Number of Structures

Total Estimated Damages

% of Total Damages

Agriculture 2,356 30 $530 -- $1,249,533 1 Urban

Residential 2,643 34 $41,091 4,251 $108,603,502 78 Commercial 2,759 35 $9,732 331 $26,850,544 19 Industrial 32 0 $74,783 1 $2,393,060 2

Subtotal Urban 5,434 69 $125,606 4,583 $137,847,106 99

TOTAL 7,790 99 $126,136 4,583 $139,096,639 100

1 Based on the data presented in Sturdivant et al. 2004

For improved flood control, height of several sections of the 85-mile long levee system would be raised to meet current design criteria. The extent of required improvements was determined from hydraulic modeling of flood containment capacity. Modeling results indicated that, during large flood events, height increases up to 4 feet would be required for flood control.

Levee improvements required in the upper 17-mile reach of the RGRP, previously addressed in a separate EA (USIBWC 2007), are not included in this document.

Improvements to the levee system are also needed to retain levee system certification by the Federal Emergency Management Agency (FEMA), used as a criteria for development of Flood Insurance Rate Maps. Draft maps issued by FEMA in spring 2007 would classify extensive areas currently protected by the RGRP levee system as insufficiently protected, where residents would be required to purchase additional flood insurance.

The USIBWC also identified as a high priority the need to perform silt removal along the river channel and arroyos that intersect the main stem of the Rio Grande that have caused interference with normal flows in the river. Efficient delivery of water for irrigation and other uses in the United States and Mexico, along with flood control, is the core mission of the RGRP. Silt removal would be performed by dredging. River channel rectification actions may also be required to modify the existing channel to conform to existing agreements with Mexico.

1.2 USIBWC AUTHORITY

The International Boundary and Water Commission (IBWC), which before 1944 was known as the International Boundary Commission, was created by the Convention of 1889, and consists of a United States Section (USIBWC) and a Mexican Section (MxIBWC). The IBWC was established to apply the rights and obligations the Governments of the United States and Mexico assumed under the numerous boundary and water treaties and related agreements.

Application of the rights and obligations are accomplished in a way that benefits the social and economic welfare of the people on both sides of the boundary and improves relations between the two countries.

106°30'0"W

106°0'0"W

106°30'0"W

106°0'0"W

31°30'0"N

31°30'0"N

Figure 1 Rio Grande Rectification Project - Upper Reach

International Boundary and Water Commission, United States Section¹ 0 2 4 6 81

Miles

0 3 6 9 121.5 Kilometers

Scale = 1: 200,000

Dona Ana County

Otero County

El Paso County Hudspeth County Culberson County

Rio Grande

Chihuahua

MEXICO

Texas

UNITED STATES

New Mexico Juarez

UNITED STATES

Socorro

El Paso

Las Cruces

U ppe r Rea ch

Lo wer Reach

Irrigated Areas

Floodway

Urban Areas

Military Reservation

LEGEND

106°0'0"W

105°30'0"W

31°30'0"N

31°0'0"N

106°0'0"W

105°30'0"W

31°30'0"N

31°0'0"N

Fi gu re 2 Rio Grande Rectification Project - Lower Reach

International Boundary and Water Commission, United States Section¹ 0 2 4 6 81

Miles

0 3 6 9 121.5 Kilometers

Scale = 1: 200,000

Dona Ana County

Otero County

El Paso County Hudspeth County Culberson County

Rio Grande

Chihuahua

MEXICO

Texas

UNITED STATES

New Mexico Juarez

UNITED STATES

Socorro

El Paso

Las Cruces

U ppe r Rea ch

Lo wer Reach

Irrigated Areas

Floodway

Urban Areas

Military Reservation

LEGEND

1-5 USIBWC

The mission of the USIBWC has five components:

1. Regulation and conservation of waters of the Rio Grande for use by the United States and Mexico through joint construction, operation, and maintenance of international storage dams and reservoirs and plants for generating hydroelectric energy at the dams, and regulation of the Colorado River waters allocated to Mexico;

2. Distribution of waters of the Rio Grande and the Colorado River between the two countries;

3. Protection of land along the Rio Grande from floods through levee and floodway projects, and solution of border sanitation and other border water quality problems;

4. Preservation of the Rio Grande and Colorado River as the international boundary; and

5. Demarcation of the land boundary.

The third mission of the USIBWC covers the proposed raising of the RGRP levee reach, and the fourth mission covers dredging of the river channel.

1.3 SCOPE OF THE ENVIRONMENTAL REVIEW

1.3.1 Regulatory Compliance Framework

Federal agencies are required to take into consideration the environmental consequences of proposed and alternative actions in the decision-making process under the National Environmental Policy Act (NEPA) of 1969, as amended. The President’s Council on Environmental Quality issued regulations to implement NEPA that include provisions for both the content and procedural aspects of the required environmental analysis. In 1978, the Council on Environmental Quality issued regulations implementing the process (40 Code of Federal Regulations [CFR] 1500-1508).

The USIBWC regulations for implementing NEPA are specified in Operational Procedures for Implementing Section 102 of the National Environmental Policy Act of 1969, Other Laws Pertaining to Specifics Aspects of the Environment and Applicable Executive Orders (46 FR 44083, September 2, 1981). These federal regulations establish both the administrative process and substantive scope of the environmental impact evaluation designed to ensure that deciding authorities have a proper understanding of the potential environmental consequences of a contemplated course of action. The Council on Environmental Quality regulations require that an EA:

• Briefly provide evidence and analysis to determine whether the Proposed Action might have significant effects that would require preparation of an EIS. If analysis determines that the environmental effects would not be significant, a Finding of No Significant Impact is prepared;

• Facilitate the preparation of an EIS, when required; or

• Aid an agency’s compliance with NEPA when no EIS is necessary.

1-6 USIBWC

1.3.2 Resource Areas Evaluated

This EA identifies and evaluates the potential environmental consequences that may result from implementation of the Proposed Action and No Action alternative. It also characterizes the affected environment and describes, when required, mitigation measures to prevent or minimize impacts to environmental and cultural resources. Potential environmental consequences of the Proposed Action are discussed by resource area in Section 4 of this EA.

The following resource areas and issues are included in the evaluation:

• Biological resources (vegetation, wildlife, threatened and endangered species, wetlands, aquatic habitats, and unique or sensitive areas);

• Cultural resources (archaeological, architectural) and Native American consultation;

• Water resources (flood control, water supply and management, agricultural water use, and water quality);

• Land use (urban development, agricultural use, and other significant uses);

• Community resources (socioeconomics, environmental justice, and transportation); and

• Environmental health (air quality, noise, and public health and environmental hazards).

Analyses of natural and cultural resources for the affected environment and environmental consequences are based on the narrow area surrounding the existing RGRP area. Analyses of environmental consequences also include potential indirect impacts adjacent to the levee and the region depending on the resource and its relationship to the Proposed Action and the No Action Alternative. Reference values for air quality, socioeconomics, and environmental justice are evaluated on a regional basis (county level).

This EA has been tiered-off from a Programmatic EIS prepared by the USIBWC for long-term improvements three Rio Grande flood control projects, including the RGRP (USIBWC 2008a). Descriptions of environmental baseline conditions along the RGRP presented in this EA are summaries of more detailed information provided in the Programmatic

EIS.

Descriptions of environmental conditions are supplemented with findings of studies conducted in support of the EA preparation. Those findings are also used in the ongoing update of existing RGRP studies in the areas of biological resources (Parsons 2001) and cultural resources (Brown et al. 2003 and Gibbs et al. 2005).

1.4 ENVIRONMENTAL COORDINATION AND COMPLIANCE ANALYSIS

Table 1.2 is a summary of regulatory and/or permitting requirements potentially applicable to improvements under consideration, potential compliance issues, and anticipated level of environmental coordination.

1-7 USIBWC

Table 1.2 Summary of Environmental Coordination and Compliance by Resource Area

Agency or Organization

Regulation or Issue Level of USIBWC Coordination

Biological Resources

U.S. Fish and Wildlife Service

(USFWS)

Endangered Species Act of 1973 (Public Law 93-205) and amendments of 1988 (Public Law 100-478) USFWS Coordination Act (916 USC 661, et seq.)

Migratory Bird Treaty Act of 1918, as amended (16 USC 703-712; Ch. 128;

July 13, 1918; 40 Stat. 755)

Consultation to determine whether migratory birds and T&E species could be affected.

Section 7 of the Act requires formal consultation if significant adverse impacts to federally listed threatened and endangered species could occur due to the Proposed Action.

Requires federal agencies to consult with USFWS regarding impact of Proposed Action.

Texas Parks and Wildlife Department

(TPWD)

Chapters 67 and 68 of the TPWD Code, and Section 65.171-65.184 of the Texas Administrative Code

Coordination concerning impacts on wildlife and threatened and endangered species

Cultural Resources

State Historic Preservation Office

(SHPO)

National Historic Preservation Act (NHPA) of 1966, as amended (16 USC 470 et seq.)

American Indian Religious Freedom Act (AIRFA), 1978

Native American Graves Protection and Repatriation Act (NAGPRA), Ensure compliance with NHPA, AIRFA and

NAGPRA.

The Texas Historic Commission (THC) may suggest conditions and mitigation measures following review of the Draft EA.

Water Resources

U.S. Army Corps of Engineers

(USACE)

Section 10 of the Rivers and Harbors Act of 1899 Section 404 of the Clean Water Act

(33 USC 1344)

Pre-permit application. If waters of the United States are affected, mitigation plan and permit application would be required.

Texas Commission on Environmental Quality (TCEQ)

Section 401 of the Clean Water Act

(33 USC 1344);

Section 26.040 of Texas Water Code

Section 401 Certification: conditions and mitigation measures may be stipulated for the 401 permit; coordination is typically a function of the USACE permitting process.

United States Environmental Protection Agency

(USEPA)

Section 402 of the Clean Water Act Section 404 of the Clean Water Act

Requirements for National Pollutant Discharge Elimination System construction permit and Storm Water Pollution Prevention Plan preparation.

Section 404 Certification; coordination is typically a function of the USACE permitting process.

Other Issues Natural Resources Conservation Service (NRCS)

Farmland Protection Policy Act Determination that no unique or prime farmland would be affected by the federal project.

U.S. Border Patrol (USBP) Levee Road Usage Coordination during construction activities.

Irrigation Districts Modifications to intake channel and construction along irrigation canals

El Paso County Water Improvement District No. 1 Hudspeth County Conservation and Reclamation District No. 1

1-8 USIBWC

1.5 ORGANIZATION OF THE ENVIRONMENTAL ASSESSMENT

This Environmental Assessment is composed of the following sections:

Section 1 identifies the purpose of and need for the Proposed Action, defines the scope of the environmental review, and provides an environmental coordination and compliance analysis.

Section 2 describes the Proposed Action and No Action Alternative, and summarizes potential environmental impacts.

Section 3 presents information on the affected environment, providing a basis for analyzing the impacts of the Proposed Action.

Section 4 analyzes the environmental consequences of proposed improvements to the

RGRP.

Section 5 describes best management practices for construction and potential mitigation actions.

Section 6 describes agencies and organizations consulted, and contributors to the EA preparation.

Section 7 is a list of cited references and source documents relevant to preparation of the

EA.

Support documentation is provided in three appendices, as follows:

Appendix A Detailed maps of levee alignment and potential improvement areas.

Appendix B Biological evaluation update for the RGRP

Appendix C Draft EA review correspondence

Final Environmental Assessment Description of Alternatives

2-1 USIBWC

SECTION 2

DESCRIPTION OF ALTERNATIVES

This section identifies measures associated with two alternatives for improvements to the Rio Grande Rectification Project: a No Action Alternative, the continued implementation of current operation and maintenance (O&M) practices, and one Proposed Action, including levee improvements and dredging the river channel of the Rio Grande.

2.1 NO ACTION ALTERNATIVE

The RGRP, located in El Paso and Hudspeth Counties, Texas, was constructed between 1934 and 1938. It extends 91 river miles along the Rio Grande in El Paso and Hudspeth County Texas. The RGRP begins approximately 140 feet downstream of the American Diversion Dam in El Paso at the beginning point of the Western Land Boundary between the United States and Mexico, and continues downstream to the Little Box Canyon below Fort Quitman, Texas. The purpose of the project was to stabilize the international river boundary and provide flood protection for both countries in urban, suburban, and agricultural areas. The RGRP also provides irrigation and drainage benefits to agricultural lands in both countries as well as urban areas on both sides of the river.

The 1933 Convention provided for the creation, operation, and maintenance of an artificial channel whose centerline became the new international boundary. The RGRP was constructed by straightening the river channel and developing a narrow floodway by constructing levees on both sides of the river. The channel straightening process removed some meanders and resulted in a reduction in the river length from 155 to 86 miles. In addition, the river gradient was increased from approximately 2 feet per mile to 3.2 feet per mile. To compensate for the increase in river gradient, the following four grade control structures were built: Island, Tornillo, Alamo, and Guayuco. The average channel depth along the RGRP is 3 to 5 feet. The width of the river channel is between 66 and 100 feet and its capacity is 1,000 cubic feet per second (cfs).

The floodway width averages 590 feet and its capacity is 11,000 cfs. The project includes 85.4 miles of levees on the U.S. side, and 83.7 miles of levees on the Mexico side.

The average levee height is 7.2 feet, the average top width is 20 feet. The project was designed for the channel to safely contain a 100-year flood event.

2.1.1 Levee System Maintenance

The USIBWC conducts the following activities for maintenance of the RGRP levee system, either routinely or on an as-needed basis:

• Grade and resurface maintenance road on levees

• Mow/cut brush/woody vegetation from levee slopes; repair erosion-related damage

• Maintain grass vegetation

2-2 USIBWC

Maintenance of levees includes road maintenance, mowing of slopes, and erosion repairs.

Maintenance supervisors drive the length of the U.S. levees each week to check condition, and repairs are conducted as needed. Resurfacing of levee roads, using gravel, takes place in a 20-year cycle that requires annual improvements at selected locations. Slopes are mowed continually with farm tractors and rotary slope mowers. Approximately 100 river miles of levee slope are mowed annually. Bank stabilization is performed as needed or after high flow events, about four to five of which occur per year. Typically after a high flow event, five to six locations are stabilized.

2.1.2 Floodway…