04_Final Mission SEA and FONSI 20111031.pdf

FINAL SUPPLEMENTAL ENVIRONMENTAL ASSESSMENT

IMPROVEMENTS TO THE MISSION PROTECTIVE LEVEE SYSTEM,

HIDALGO COUNTY, TEXAS

UNITED STATES INTERNATIONAL BOUNDARY AND

WATER COMMISSION

Prepared for:

United States Section

International Boundary and Water Commission

Prepared by:

TRC Environmental Corporation

October 2011

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COVER SHEET

AND

FINDING OF NO SIGNIFICANT IMPACT

IMPROVEMENTS TO THE MISSION PROTECTIVE LEVEE SYSTEM

LEAD AGENCY: United States Section, International Boundary and Water Commission

(USIBWC)

PROPOSED ACTION: Improvements to the Mission Protective Levee System (Mission Levee) to re-establish a canal access and maintenance road in order to address contractual obligations between the USIBWC and the United Irrigation District (UID)

REPORT DESIGNATION: Supplemental Environmental Assessment

ABSTRACT: The Mission Levee Protective System is a component of the Lower Rio Grande Flood Control Project (LRGFCP) that conveys floodwater diverted from the Rio Grande to the Laguna Madre in the Gulf of Mexico and protects urban, suburban, and highly developed irrigated farmland along the Rio Grande delta in the United States and Mexico. In 2009, the Mission and Common Levee Systems were raised in order to meet Federal Emergency Management Agency (FEMA) flood protection criteria. However, during the levee raising efforts, a canal access and maintenance road between the toe of the Mission Levee and the Mission Main Canal was eliminated by the expanded levee.

The purpose of the Proposed Action is to re-establish the canal access and maintenance road in order to address the maintenance requirements of the Mission Main Canal and to meet contractual obligations between the USIBWC and UID.

This Supplemental Environmental Assessment (SEA) evaluates the potential impacts of the No Action Alternative, the Preferred Alternative, Alternative 2 and Alternative 3. Potential impacts on natural, cultural, and other resources were evaluated.

FINDING OF NO SIGNIFICANT IMPACT

IMPROVEMENTS TO THE MISSION PROTECTIVE LEVEE SYSTEM IN HIDALGO

COUNTY, TEXAS

LEAD AGENCY: United States Section, International Boundary and Water Commission

BACKGROUND

The Lower Rio Grande Flood Control Project (LRGFCP) extends approximately 186 miles from Peñitas, Texas to the mouth of the Rio Grande in the Gulf of Mexico, along Hidalgo, Cameron and Willacy Counties. The project was the result of a 1932 agreement between the United States and Mexico to provide flood protection to urban, suburban, and agricultural lands in both countries. The LRGFCP conveys floodwater diverted from the Rio Grande to the Laguna Madre in the Gulf of Mexico and protects urban, suburban, and highly developed irrigated farmland along the Rio Grande delta in the United States and Mexico.

In 2009, the Mission and Common Levee Systems were raised in order to meet Federal Emergency Management Agency (FEMA) flood protection criteria. However, during the levee raising efforts, a canal access and maintenance road between the toe of the Mission Levee and the Mission Main Canal was eliminated by the expanded levee. Due to the size of the Mission Main Canal, the United Irrigation District (UID) is currently unable to properly maintain the canal without the eliminated canal access and maintenance road. In addition, Contract IBM- 6513 between the USIBWC and UID requires the USIBWC to maintain a minimum 10-foot wide access road between the toe of the Mission Levee and the Mission Main Canal.

The purpose of the Proposed Action is to re-establish the canal access and maintenance road in order to address the maintenance requirements of the Mission Main Canal. Improvements are needed to meet contractual obligations between the USIBWC and UID.

PROPOSED ACTION

The Preferred Alternative consists of modifying the Mission Main Canal from 1.1 miles west of Bentsen Palm Road east to the Military Road bridge crossing, a distance of 2.9 miles. In order to re-establish the canal access and maintenance road, the canal would be narrowed by approximately 15 feet (the width necessary to re-establish the road) with fill material obtained from commercial sources outside the levee system. The Mission Main Canal would be lined with concrete in order to regain carrying capacity lost by narrowing the canal. Construction would occur between October 1 and March 15 to coincide with the lowest demand period for the

UID.

Other modifications would include minor excavation and reshaping of the canal to ensure proper elevation and slope of the modified canal, re-grading the northern access and maintenance road to prevent erosion damage to the canal and to improve access for construction equipment, and grading and adding road base (caliche) to the re-established canal access and maintenance road.

Drainage and irrigation structures are located along the canal. These structures may require modification as a result of canal modification. The USIBWC, in coordination with the appropriate irrigation or drainage district, may use the following modification options: remove and replace the structures in-kind, extend the structures to the new canal edge, remove and plug the structures with concrete or quality material, or abandon the structures and cover them in-place with concrete or quality material.

The USIBWC would be responsible for grading and maintenance activities associated with the re-established canal access and maintenance road. Routine maintenance activities such as vegetation management along the Mission Main Canal would be the responsibility of the UID.

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 including provisions for both the content and procedural aspects of the required Supplemental Environmental Assessment (SEA). The USIBWC completed an SEA of the potential environmental consequences of re-establishing a canal access and maintenance road between the toe of the Mission Levee and the Mission Main Canal. The SEA, which supports this Finding of No Significant Impact (FONSI), evaluated the No Action Alternative, the Preferred Alternative, Alternative 2 and Alternative 3. Based on the evidence presented in the Final SEA, impacts resulting from the Preferred Alternative have been identified below.

Preferred Alternative

Biological Resources

Canal modification activities would affect approximately 8.9 acres of terrestrial vegetation and

22.5 acres of aquatic vegetation along the Mission Levee project area through vegetation removal and fill activities. Impacts would occur on the landside levee toe, the Mission Main Canal and the riverside slope of the northern canal access and maintenance road. Approximately

5.3 acres of the vegetation impacted would include low quality, non-native, grass-covered toe of the existing levee and slopes of the northern canal access road. Approximately 3.6 acres of herbaceous riparian vegetation associated with the Mission Main Canal banks would be impacted. No wetlands would be impacted.

It is anticipated that most wildlife species present in the project area would move to adjacent, undisturbed areas during construction and rapidly re-colonize the area after the work is completed and after the vegetation has been re-established. However, no similarly suitable habitat is adjacent to the Mission Main Canal for amphibians and reptiles inhabiting the canal banks. Canal modification activities would eliminate all aquatic flora and fauna within the Mission Main Canal through dewatering, fill placement, and concrete lining activities.

The project area is composed primarily of regularly maintained areas that provide relatively low quality habitat for most wildlife species. Routine maintenance activities would remain unchanged. The area of proposed disturbance is located along previously disturbed areas and regular maintenance activities are conducted along the levee and canal. Based on USIBWC commitments identified under the Best Management Practices section, the U.S. Fish and Wildlife Service concurred, in a letter dated June 7, 2011, that the Preferred Alternative would not adversely affect federally listed species, their habitats, or designated critical habitat. The Preferred Alternative may affect twelve state-listed species. The USIBWC would provide a qualified environmental monitor to survey for T&E species to prevent direct take of any state-listed species.

Cultural Resources

Construction activities would take place along the current levee and canal right-of-way. The use of heavy equipment to add and move soil material for canal modification may cause soil disturbance several inches deep in the project area. Upon the investigation of two High Probability Areas within the Area of Potential Affect (APE) through pedestrian survey and shovel testing, no archeological resources were observed within the APE. Given these data, no adverse effects to archeological resources would be anticipated from construction activities associated with the Preferred Alternative.

Architectural resources may be affected by canal modification activities. Potential effects include vibration and ground disturbance from the use of heavy equipment during construction as well as may include the alteration of architectural traits by modification of existing structures.

A survey of the architectural resources for National Register of Historic Places (NRHP) eligibility documented two historic resources: the 2.9-mile portion of the Mission Protective Levee System and the adjacent Mission Main Canal of the UID. Each of these resources has associated features, 24 of which are within the APE. In a letter dated August 2, 2011, the Texas Historical Commission (THC) determined that the Mission Main Canal was not potentially eligible for listing on the NRHP but the Mission Protective Levee System was potentially eligible for listing. The THC concurred, in a letter dated August 2, 2011, that there would be no adverse effect on the Mission Protective Levee by the Preferred Alternative. No resources or concerns to Native American Tribes have been identified by the Preferred Alternative.

Water Resources

The project would disturb approximately 8.9 acres of terrestrial habitat. The project would comply with the Texas Pollutant Discharge Elimination System (TPDES) Construction General Permit as administered by the Texas Commission on Environmental Policy. A Storm Water Pollution Prevention Plan (SWPP) would be prepared and implemented and a construction notice would be posted at the project site.

The Mission Main Canal would be completely dewatered prior to any construction activities.

Temporary dams would be placed within the Mission Main Canal upstream and downstream of the project area to ensure fill material, sediment and construction debris would not enter either the Rio Grande or the rest of the UID system. Therefore, no impacts are expected to surface water and groundwater under the Preferred Alternative.

Land Use

Construction activities associated with the Preferred Alternative would occur from the landside toe of the levee to the northern canal access and maintenance road. Two U.S. Fish and Wildlife Service (USFWS) National Wildlife Refuges, a Texas Parks and Wildlife Department (TPWD) State Park and residential properties are located adjacent to the project area. It is anticipated that periodic, temporary obstructions would occur from construction traffic. No prime or unique farmlands are located within the project area in Hidalgo County.

Community Resources

During construction activities, a temporary influx of employment, business sales volume, and income would occur in Hidalgo County. A small but positive, temporary economic contribution to the local community would occur as a result of the Preferred Alternative. The benefit would be small for Hidalgo County given its large economic base, less than 1.0% of the annual county employment, income and sales values. No adverse impacts to 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 use for equipment mobilization to staging areas.

Environmental Health

Estimated air emissions of any of the six criteria pollutants during construction would be discontinuous and represent less than 0.1% of the annual emissions inventory for Hidalgo 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 Mission Levee improvements.

Cumulative Impacts

A review of current and proposed local, state, and federal activities in and near the project area identified the Mission and Common Levee Improvements Project as having identified impacts that occur in the project area. However, the cumulative effects of these activities would not be significant.

Best Management Practices

Best management practices would be implemented as part of the Preferred Alternative to minimize the potential for impacts to natural and cultural resources.

A SWPPP would be developed during project design to minimize impacts to receiving water, as specified by TCEQ regulations for construction projects. During project construction, methods such as soil wetting would be employed to prevent erosion from unvegetated slopes and/or corridors and to minimize additional air quality impacts from construction activities. Limiting unnecessary idling of construction vehicles and shutting down construction machines that are not in use would minimize additional air quality impacts from construction activities. Existing access points to the levee would remain in service with no change to lateral access to the levee road.

Revegetation with native herbaceous species along the construction corridor would be implemented after construction is complete. Native vegetation species would be determined through coordination with the USFWS and the TPWD. USIBWC would compensate the loss of riparian habitat on a 2:1 acre basis (2 acres protected for every 1 acre disturbed) for a total of 7.2

IMPROVEMENTS TO THE MISSION PROTECTIVE LEVEE SYSTEM,

HIDALGO COUNTY, TEXAS

UNITED STATES INTERNATIONAL BOUNDARY AND

WATER COMMISSION

Prepared for:

United States Section

International Boundary and Water Commission

Prepared by:

TRC Environmental Corporation

October 2011

Improvements to the Mission Protective Levee System Final Supplemental Environmental Assessment Table of Contents i

Table of Contents Page

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

1.1 Introduction .......................................................................................................... 1-1

1.2 Purpose and Need for Action ............................................................................... 1-1

1.3 Background .......................................................................................................... 1-5

1.3.1 USIBWC Authority ................................................................................. 1-5

1.3.2 Levee System Description ....................................................................... 1-5

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

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

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

2.2 Preferred Alternative: Canal Modification .......................................................... 2-2

2.3 Alternative 2: Sheet Pile Wall .............................................................................. 2-4

2.4 Alternative 3: Retention Wall .............................................................................. 2-5

SECTION 3 : AFFECTED ENVIRONMENT AND ENVIRONMENTAL

CONSEQUENCES .............................................................................................. 3-1

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

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

3.1.2 Wetlands and Waterbodies ...................................................................... 3-5

3.1.3 Wildlife .................................................................................................... 3-7

3.1.4 Aquatic Ecosystems ................................................................................. 3-8

3.1.5 Federally Listed Threatened and Endangered Species .......................... 3-10

3.1.6 State-Listed Threatened and Endangered Species ................................. 3-14

3.2 Cultural Resources ............................................................................................. 3-20

3.2.1 Previous Cultural Resources Studies ..................................................... 3-21

3.2.2 Archeological Resources ....................................................................... 3-22

3.2.3 Architectural Resources ......................................................................... 3-23

3.2.4 Native American Resources ................................................................... 3-24

3.3 Water Quality ..................................................................................................... 3-25

3.4 Land Use ............................................................................................................ 3-27

3.4.1 Natural Resources Management and Recreational Areas .................. 3-27

3.4.2 Agricultural Land ................................................................................... 3-29

3.4.3 Residential Areas ................................................................................... 3-29

Final Supplemental Environmental Assessment List of Acronyms ii

3.5 Community Resources ....................................................................................... 3-30

3.5.1 Socioeconomics ..................................................................................... 3-30

3.5.2 Environmental Justice ............................................................................ 3-33

3.5.3 Transportation ........................................................................................ 3-35

3.6 Environmental Health ........................................................................................ 3-36

3.6.1 Air Quality ............................................................................................. 3-36

3.6.2 Noise 3-39

3.6.3 Hazardous Materials .............................................................................. 3-41

3.7 Cumulative Impacts ........................................................................................... 3-42

SECTION 4 : BEST MANAGEMENT PRACTICES ............................................................... 4-1

4.1 Engineering Measures .......................................................................................... 4-1

4.2 Natural Resources ................................................................................................ 4-1

4.3 Cultural Resources ............................................................................................... 4-2

SECTION 5 : ENVIRONMENTAL COMPLIANCE AND COORDINATION ...................... 5-1

5.1 Consultation ......................................................................................................... 5-1

5.2 List of Contributors .............................................................................................. 5-1

SECTION 6 : REFERENCES .................................................................................................... 6-1

Appendices

APPENDIX A: DETAILED MAPS OF THE MISSION LEVEE PROJECT AREA

APPENDIX B: WATERS OF THE UNITED STATES DELINEATION REPORT

APPENDIX C: PHOTOGRAPHIC LOG

APPENDIX D: CORRESPONDENCE

APPENDIX E: TEXAS NATURAL DIVERSITY DATABASE

Final Supplemental Environmental Assessment Table of Contents iii

List of Figures

Figure 1-1: Mission Levee Vicinity Map ..................................................................................... 1-3

Figure 2-1: Current Cross-section of the Mission Levee and Mission Main Canal .................... 2-1

Figure 2-2: Typical Cross-section of the Preferred Alternative: Canal Modification ................. 2-3

Figure 2-3: Location of Water Transfer between HCID #1 and UID .......................................... 2-3

Figure 2-4: Typical Cross-section of Alternative 2: Sheet Pile Wall .......................................... 2-4

Figure 2-5: Typical Cross-section of Alternative 3: Retention Wall ........................................... 2-5

List of Tables

Table 1-1: Summary of Environmental Coordination and Compliance ...................................... 1-7

Table 2-1: Summary of Environmental Impacts of Proposed Mission Levee Improvements ..... 2-6

Table 3-1: Acreages of Vegetation Impacts for All Alternatives ................................................ 3-5

Table 3-2: Federally Listed T&E Species with the Potential to Occur in the Vicinity of the Mission Levee Project Area ..................................................................................... 3-10

Table 3-3: State-Listed T&E Species with the Potential to Occur ............................................ 3-15

Table 3-4: Economic Impacts of the Mission Levee System in Hidalgo County, Texas .......... 3-32

Table 3-5: Percentage of Minority Populations and Poverty Rates in Hidalgo County, Texas ........................................................................................................................ 3-34

Table 3-6: Air Emissions for Improvements to the Mission Protective Levee System ............. 3-38

Table 3-7: Cumulative Impacts of the Preferred Alternative..................................................... 3-43

Table 5-1: Supplemental Environmental Assessment Mailing List of Agencies and Organizations ............................................................................................................. 5-1

Table 5-2: List of Contributors to the Supplemental Environmental Assessment....................... 5-3

Final Supplemental Environmental Assessment List of Acronyms iv

List of Acronyms

AQCR Air Quality Control Regions APE Area of Potential Effect AIRFA American Indian Religious Freedom

Act AHPA Archeological and Historic Preservation

Act BRGVSP Bentsen-Rio Grande Valley State Park CAA Clean Air Act CEQ Council on Environmental Quality CERCLA Comprehensive Environmental

Response, Compensation, and Liability Act

CFR Code of Federal Regulations CWA Clean Water Act dB Decibels DNL Day-night average sound level EA Environmental Assessment FEMA Federal Emergency Management

Agency FM Farm-to-Market GPM Gallons per Minute H:V horizontal feet per foot of height HCID #1 Hidalgo County Irrigation District #1 HPA High Probability Area IBWC International Boundary and Water

Commission LRGFCP Lower Rio Grande Flood Control

Project LRGNWR Lower Rio Grande National Wildlife

Refuge LRGV Lower Rio Grande Valley MBTA Migratory Bird Treaty Act NAAQS National Ambient Air Quality

Standards NABA North American Butterfly Association NAGPRA Native American Graves Protection and

Repatriation Act NEPA National Environmental Policy Act NHPA National Historic Preservation Act NPDES National Pollutant Discharge

Elimination System

NRHP National Register of Historic Places NRCS Natural Resources Conservation Service NTS Not to Scale PEIS Programmatic Environmental Impact

Statement PL Public Law RCRA Resource Conservation and Recovery

Act ROW Right-of-way SARA Superfund Amendments and

Reauthorization Act SEA Supplemental Environmental

Assessment SHPO State Historic Preservation Office SWPPP Storm Water Pollution Prevention Plan T&E Threatened and Endangered Species TAC Texas Administrative Code TCEQ Texas Commission on Environmental

Quality THC Texas Historical Commission TPDES Texas Pollutant Discharge Elimination

System TxNDD Texas Natural Diversity Database TPWD Texas Parks and Wildlife Department TWDB Texas Water Development Board TRC TRC Environmental Corporation TSCA Toxic Substances Control Act UID United Irrigation District US United States USACE United States Army Corps of Engineers USBP United States Border Patrol USC United States Code USDA United States Department of

Agriculture USDOT United States Department of

Transportation USEPA United States Environmental Protection

Agency USFWS United States Fish and Wildlife Service USIBWC United States Section, International

Boundary and Water Commission WIID Water Information Integration and

Dissemination

Final Supplemental Environmental Assessment Purpose and Need for the Proposed Action

1-1

SECTION 1:

PURPOSE AND NEED FOR THE PROPOSED ACTION

1.1 INTRODUCTION

The United States Section of the International Boundary and Water Commission (USIBWC) prepared this Supplemental Environmental Assessment (SEA) for proposed improvements along a 2.9-mile section of the Mission Protective Levee System (Mission Levee) located in Hidalgo County, Texas. The Mission Levee is a component of the Lower Rio Grande Flood Control Project (LRGFCP) that conveys floodwater diverted from the Rio Grande to the Laguna Madre in the Gulf of Mexico and protects urban, suburban, and highly developed irrigated farmland along the Rio Grande delta in the United States and Mexico.

The Proposed Action would involve improvements to re-establish a 10-foot wide canal access and maintenance road along the levee side of the Mission Main Canal from 1.1 miles west of Bentsen Palm Road to the Military Road bridge crossing. Figure 1-1 shows the layout of the project area, main geographical features, and levee mile markers. Appendix A provides detailed maps of the project area.

This SEA supplements the Final Environmental Assessment Improvements to the Mission and Common Levee Systems (USIBWC 2007) and the Final Programmatic Environmental Impact Statement – Improvements to the USIBWC Rio Grande Flood Control Projects along the Texas- Mexico Border (USIBWC 2008) completed by the USIBWC for long-term improvements to Rio Grande flood control projects operated along the Texas-Mexico border. Descriptions of environmental conditions along the Mission Levee presented in this SEA are summaries of more detailed information provided in the 2008 Programmatic Environmental Impact Statement (PEIS) and the 2007 Final Environmental Assessment, as well as the Waters of the U.S.

Delineation Report (Appendix B) of this SEA. These descriptions are supplemented with data from biological and cultural resources field evaluations conducted in support of the SEA preparation.

1.2 PURPOSE AND NEED FOR ACTION

In 2009, the Mission and Common Levee Systems were raised in order to meet Federal Emergency Management Agency (FEMA) flood protection criteria. During the levee raising efforts, the widening of the levee eliminated a canal access and maintenance road between the toe of the Mission Levee and the Mission Main Canal. Due to the size of the Mission Main Canal, the United Irrigation District (UID) is currently unable to properly maintain the canal without the eliminated canal access and maintenance road. In addition, Contract IBM-6513 between the USIBWC and UID requires the USIBWC to maintain a minimum 10-foot wide access road between the toe of the Mission Levee and the Mission Main Canal.

The purpose of the Proposed Action is to re-establish the canal access and maintenance road in order to address the maintenance requirements of the Mission Main Canal. Improvements are needed to meet contractual obligations between the USIBWC and UID.

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1-3

Figure 1-1: Mission Levee Vicinity Map

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1-5

1.3 BACKGROUND

1.3.1 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. 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. The mission of the USIBWC has five components, as follows:

• 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, reservoirs, and plants for generating hydroelectric energy at the dams, and regulation of the Colorado River waters allocated to Mexico;

• distribution of waters of the Rio Grande and the Colorado River between the two countries;

• protection of lands along the Rio Grande from floods through levee and floodway projects and resolution of border sanitation and other border water quality problems;

• preservation of the Rio Grande and the Colorado River as the international boundary;

and

• demarcation of the land boundary.

1.3.2 Levee System Description

The LRGFCP extends approximately 186 river-miles from Peñitas, Texas to the mouth of the Rio Grande in the Gulf of Mexico, along Hidalgo, Cameron, and Willacy counties. The project was the result of a 1932 agreement between the United States and Mexico to provide flood protection to urban, suburban, and agricultural lands in both countries. The LRGFCP includes the Mission Protective Levee System that extends approximately 12 miles from the Town of Peñitas east to its junction with the Main Floodway.

The following terminology is used throughout the report:

• Floodway: In this SEA, the floodway is restricted to the area between the Rio Grande and the Mission Levee.

• Riverside of levee: The area from the center of the Mission Levee toward the Rio Grande.

• Landside of levee: The area from the center of the Mission Levee extending away from the Rio Grande.

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• Levee side of canal: The area from the toe of the Mission Levee to the southern edge of the Mission Main Canal. For the purposes of this report, this area is assumed to be 5 feet wide.

• Northern access and maintenance road: The existing raised maintenance road located along the northern edge of the Mission Main Canal.

• Project area: The project area is assumed to be the area from the landside of the Mission Levee to the northern edge of the existing Mission Main Canal access road.

• Right-of-way (ROW): The areas on the riverside and landside of the Mission Levee managed by the USIBWC. The USIBWC has access to the ROW through land easements.

• Irrigation canals: Excavated drainages that provide water from the Rio Grande to irrigate agricultural lands.

• Area of Potential Effect: The area where cultural resources may occur and may be affected by construction activities.

1.4 ENVIRONMENTAL COORDINATION AND COMPLIANCE

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 (CEQ) issued regulations to implement NEPA that include provisions for both the content and procedural aspects of the required environmental analysis. In 1978, the CEQ 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 Specific 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 the USIBWC has a proper understanding of the potential environmental consequences of a contemplated course of action.

Table 1-1 is a summary of regulatory and/or permitting requirements potentially applicable to improvements under consideration, potential compliance issues, and anticipated level of environmental coordination.

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Table 1-1: Summary of Environmental Coordination and Compliance

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 [PL] 93-205) and amendments of 1988 (PL100- 478)

Fish and Wildlife Coordination Act (916 United States Code [USC] 661, et seq.)

Migratory Bird Treaty Act of 1918, as amended (16 USC 703-712; Ch. 128; July 13, 1918; 40 Stat. 755)

National Wildlife Refuge System Administration Act of 1966 (16 USC 668dd-668ee)

Section 7 of the Act requires formal consultation if significant adverse impacts to federally listed, threatened and/or endangered (T&E) species could occur due to the Proposed Action.

Requires federal agencies to consult with USFWS regarding the impact of the Proposed Action on any waters controlled or modified

Requires consultation to determine whether migratory birds and T&E species could be affected

Requires coordination with USFWS wildlife refuge managers if wildlife refuges are affected

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 (TAC)

Fish and Wildlife Coordination Act (916 USC 661, et seq.)

Requires coordination concerning impacts on wildlife and state T&E species

Coordination with State Parks Division concerning potential impacts on park tracts

Requires federal agencies to consult with TPWD regarding impact of Proposed Action on any waters controlled or modified

Cultural Resources

State Historic Preservation Officer (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), 1990

Requires federal agencies to consult with the Texas Historical Commission (THC) regarding cultural and historic resources

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Agency or Organization Regulation or Issue Level of USIBWC Coordination

Water Resources

U.S. Army Corps of Engineers (USACE)

Section 10 of the Rivers and Harbors Act of

Section 404 of the Clean Water Act (33 USC 1344)

Requires pre-permit application. If waters of the United States are affected, a mitigation plan and a 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 (NPDES) construction permit and Storm Water Pollution Prevention Plan (SWPPP) preparation.

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

Section 402 Certification would be coordinated with the TCEQ

Other Issues

Natural Resources Conservation Service (NRCS) Farmland Protection Policy Act Determination whether unique or prime farmland would be affected by the federal project

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

United Irrigation District

(UID)

Modifications and construction Mission Main Canal Coordination during construction activities

Hidalgo County Drainage District No. 1 Modifications to drainage structures Coordination during construction activities

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Agency or Organization Regulation or Issue Level of USIBWC Coordination

Local and County Governments Noise and air ordinances Coordination with the City of Mission

Coordination with Hidalgo County

North American Butterfly Association (NABA) Construction along Mission Main Canal Coordination during construction activities

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Final Supplemental Environmental Assessment Description of Alternatives

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SECTION 2:

DESCRIPTION OF ALTERNATIVES

This section identifies alternatives evaluated in this document associated with the Mission Levee Improvements Project. Under the No Action Alternative, re-establishment of the canal access and maintenance road would not be made. Under the Preferred Alternative, the re-establishment of the canal access and maintenance road would be accomplished by modifying the Mission Main Canal, while Alternatives 2 and 3 would re-establish the canal access and maintenance road by sheet pile and retention walls, respectively. Table 2-1 summarizes the potential environmental impacts of all alternatives analyzed.

The existing levee is a raised trapezoidal compacted-earth structure with an average crown width of 16 feet, an average height of 18 to 20 feet, and an approximate 3:1 side slope ratio (horizontal feet per foot of height; [H:V]). The existing levee footprint width typically ranges from 90 to 120 feet, depending on location. The existing Mission Main Canal is an earthen canal with an average bottom width of 30 feet, an average 75-foot top width, an average depth of 8 feet, and an approximate 2:1 side slope ratio.

Figure 2-1: Current Cross-section of the Mission Levee and Mission Main Canal

2.1 NO ACTION ALTERNATIVE

The No Action Alternative would retain the current configuration of the Mission Levee and the canal access and maintenance road would not be re-established. No changes in routine maintenance activities such as vegetation management and grading to repair erosion damage and maintain structural and functional integrity of the levees would be implemented. The USIBWC would continue to fail to meet its obligations to the UID under Contract IBM-6513.

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2.2 PREFERRED ALTERNATIVE: CANAL MODIFICATION

The Preferred Alternative consists of modifying the Mission Main Canal from 1.1 miles west of Bentsen Palm Road east to the Military Road bridge crossing, a distance of 2.9 miles. In order to re-establish the canal access and maintenance road, the canal would be narrowed by approximately 15 feet (the width necessary to re-establish the road) with fill material obtained from commercial sources outside the levee system. Approximately 58,100 cubic yards of fill material would be placed along the bank adjacent to the levee (levee side) of the canal and compacted. The modified canal would have a 15-foot bottom width, a 55-foot top width and 2:1 H:V side slopes. Canal elevations would be kept close to the original design as much as possible. A typical cross-section of the proposed modification is shown in Figure 2-2.

The Mission Main Canal would be lined with concrete in order to regain carrying capacity lost by narrowing the canal. Lining the canal would reduce friction loss, reduce evapotranspiration caused by vegetation in the canal, and reduce seepage out of the canal.

Other modifications would include minor excavation and reshaping of the canal to ensure proper elevation and slope of the modified canal, re-grading the northern access and maintenance road to prevent erosion damage to the canal and to improve access for construction equipment, and grading and adding road base (caliche) to the re-established canal access and maintenance road.

Drainage and irrigation structures are located along the canal. These structures would require modification as a result of canal modification. The USIBWC, in coordination with the appropriate irrigation or drainage district, would use the following modification options depending on the structures condition: remove and replace the structures in-kind, extend the structures to the new canal edge, remove and plug the structures with concrete or quality material, or abandon the structures and cover them in-place with concrete or quality material.

The Mission Main Canal would be completely dewatered during construction. The irrigation outlets that are adjacent to the section of canal to be taken out of service would be served by other connecting irrigation facilities, if available. The UID also would contract with the Hidalgo County Irrigation District No.1 (HCID #1) to provide water for the UID and their customers.

The UID would pump water out of the HCID #1 Edinburg Main Canal into the UID Mission Main Canal where the two canals intersect at approximately 0.25 mile north of Farm-to-Market (FM) Road 495 along Los Ebanos Road in Mission, Texas (Figure 2-3). Transfer of water from HCID #1 to the UID would be accomplished with the use of six, 10,000 gallons per minute (gpm) pumps and the modification of existing pipelines installed during a previous water transfer agreement in 2006. This equipment would be placed in previously impacted areas along the existing canals. Construction would occur between October 1 and March 15 to coincide with the lowest demand period for the UID.

The USIBWC would be responsible for grading and maintenance activities associated with the re-established canal access and maintenance road. Routine maintenance activities such as vegetation management along the Mission Main Canal would be the responsibility of the UID.

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Figure 2-2: Typical Cross-section of the Preferred Alternative: Canal Modification

Figure 2-3: Location of Water Transfer between HCID #1 and UID

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2.3 ALTERNATIVE 2: SHEET PILE WALL

Alternative 2 consists of installing a sheet pile wall along the Mission Levee from 1.1 miles west of Bentsen Palm Road east to the Military Road bridge crossing, a distance of 2.9 miles. Sheet piling would be located approximately 10 to 12 feet up the landside levee slope from the toe towards the levee centerline. The re-established road would be approximately 12 feet wide in order to allow for proper vehicle maneuvering. The sheet piling would be driven approximately 20 feet into the levee. Levee material would be excavated from the toe of the levee to the sheet pile wall to meet existing natural ground conditions between the toe and the canal, thus re-establishing the canal access and maintenance road. A typical cross-section of the proposed modification is shown in Figure 2-4.

Other modifications would include minor excavation and reshaping of the canal to ensure proper elevation and slope of the canal and grading and adding road base (caliche) to the re-established canal access and maintenance road. Drainage and irrigation structures are located along the canal. These structures may require modification as a result of canal modification. The USIBWC, in coordination with the appropriate irrigation or drainage district, may use the following modification options: remove and replace the structures in-kind, remove and plug the structures with concrete or quality material, or abandon the structures and cover them in-place with concrete or quality material. Construction could occur at any time of year, as the Mission Main Canal would not be modified.

The USIBWC would be responsible for grading and maintenance activities associated with the re-established canal access and maintenance road. Routine vegetation maintenance along the levee by USIBWC would remain unchanged. Routine vegetation maintenance along the south bank of the Mission Main Canal would be re-established and would be the responsibility of the UID. Routine vegetation maintenance along the north bank of the Mission Main Canal would not change and would continue to be the responsibility of the UID.

Figure 2-4: Typical Cross-section of Alternative 2: Sheet Pile Wall

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2.4 ALTERNATIVE 3: RETENTION WALL

Alternative 3 consists of installing a retention wall along the Mission Levee from 1.1 miles west of Bentsen Palm Road east to the Military Road bridge crossing, a distance of 2.9 miles. A reinforced concrete retention wall would be located approximately 10 to 14 feet up the landside levee slope from the toe towards the levee centerline. The re-established road would be approximately 12 feet wide in order to allow for proper vehicle maneuvering. The retention wall would be approximately 15 feet deep with an 8-foot wide concrete base. Levee material would be excavated from the toe of the levee to the retention wall to meet existing natural ground conditions between the toe and the canal, thus re-establishing the canal access and maintenance road. Levee material would also be excavated from the top of the levee to the retention wall in order to construct the base of the retention wall. Excavated levee material would be backfilled upon completion of construction. A typical cross-section of the proposed modification is shown in Figure 2-5.

Other modifications would include minor excavation and reshaping of the canal to ensure proper elevation and slope of the canal and grading and adding road base (caliche) to the re-established canal access and maintenance road. Drainage and irrigation structures are located along the canal. These structures may require modification as a result of canal modification. The USIBWC, in coordination with the appropriate irrigation or drainage district, may use the following modification options: remove and replace the structures in-kind, remove and plug the structures with concrete or quality material, or abandon the structures and cover them in-place with concrete or quality material. Construction could occur at any time of year as the Mission Main Canal would not be modified.

The USIBWC would be responsible for grading and maintenance activities associated with the re-established canal access and maintenance road. Routine vegetation maintenance along the levee by USIBWC would remain unchanged. Routine vegetation maintenance along the south bank of the Mission Main Canal would be re-established and would be the responsibility of the UID. Routine vegetation maintenance along the north bank of the Mission Main Canal would not change and would continue to be the responsibility of the UID.

Figure 2-5: Typical Cross-section of Alternative 3: Retention Wall

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Table 2-1: Summary of Environmental Impacts of Proposed Mission Levee Improvements

Resource Area

Environmental Impacts

No Action Alternative

Preferred Alternative: Canal

Modification Alternative 2: Sheet

Pile Wall Alternative 3:

Retention Wall

Biological Resources (Section 3.1)

Vegetation (Section 3.1.1)

Disturbances from routine maintenance

8.9 total acres of previously disturbed land impacted

8.1 total acres of previously disturbed land impacted

11.3 total acres of previously disturbed land impacted

Wetlands and Waterbodies (Section

3.1.2)

Disturbances from routine maintenance

3.6 acres of herbaceous riparian vegetation impacted;

22.5 acres of Mission Main Canal impacted

1.8 acres of herbaceous riparian vegetation impacted

1.8 acres of herbaceous riparian vegetation impacted;

Wildlife (Section 3.1.3)

Disturbances from routine maintenance

Temporary impacts from construction;

impacts to amphibians, reptiles and burrowing species; vegetation removal outside of migratory bird breeding season or surveys for nesting birds required

Temporary impacts from construction;

impacts to reptiles and burrowing species;

vegetation removal outside of migratory bird breeding season or surveys for nesting birds required

Temporary impacts from construction;

impacts to reptiles and burrowing species; vegetation removal outside of migratory bird breeding season or surveys for nesting birds required

Aquatic Ecosystems (Section 3.1.4)

Disturbances from routine maintenance

22.5 acres of aquatic habitat impacted None None

Threatened and Endangered Species (Sections 3.1.5 and

3.1.6)

Disturbances from routine maintenance

Not likely to adversely affect federally listed species; 12 state-listed species potentially impacted

Not likely to adversely affect federally listed species; 9 state-listed species potentially impacted

Not likely to adversely affect federally listed species; 9 state-listed species potentially impacted

Cultural Resources (Section 3.2)

Archeological Resources (Section

3.2.2) None None None None

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Resource Area

Environmental Impacts

No Action Alternative

Preferred Alternative: Canal

Modification Alternative 2: Sheet

Pile Wall Alternative 3:

Retention Wall

Architectural Resources (Section

3.2.3) None

Impacts to 1 identified architectural resource that is potentially eligible for listing on the National Register of Historic Places

(NRHP )

Impacts to 1 identified architectural resource that is potentially eligible for listing on the NRHP

Impacts to 1 identified architectural resource that is potentially eligible for listing on the

NRHP

Native American Resources (Section

3.2.4) None None None None

Water Resources (Section 3.3)

Water Quality (Section 3.3) None None

Short-term negligible impacts from potential erosion and runoff during construction

Short-term negligible impacts from potential erosion and runoff during construction

Land Use (Section 3.4)

Natural Resources Management and

Recreational Areas (Section 3.4.1)

None Temporary impacts from construction traffic

Temporary impacts from construction traffic

Temporary impacts from construction traffic

Agricultural Land (Section 3.4.2) None

Temporary impacts from construction traffic

Temporary impacts from construction traffic

Temporary impacts from construction traffic

Residential Areas (Section 3.4.3) None

Temporary impacts from construction traffic

Temporary impacts from construction traffic

Temporary impacts from construction traffic

Community Resources (Section 3.5)

Socioeconomics (Section 3.5.1)

Benefits provided from routine levee maintenance

Temporary influx of employment, business sales volume, and income; benefits from routine levee maintenance;

temporary impacts from construction traffic

Temporary influx of employment, business…