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FINAL

ENVIRONMENTAL IMPACT

REPORT (EIR)

PROPOSED
WATER CONSERVATION PROGRAM
AND
INITIAL WATER TRANSFER

IMPERIAL IRRIGATION DISTRICT

 

[Table of Contents for April 1986 Draft Report;
this includes the substantive chapters of the EIR, which are not included, in the Final Report]  

 

California State Clearinghouse No. 86012903

OCTOBER 1986 

IMPERIAL IRRIGATION DISTRICT
FINAL
ENVIRONMENTAL IMPACT REPORT

CONTENTS

[only the Introduction and Executive Summary texts are given here]

 

CHAPTER

1

INTRODUCTION

1-1

2

EXECUTIVE SUMMARY

2-1

2.1 Project Background

2-1

2.2 Program Description

2-1

2.3 Significant Environmental Effects and Mitigation Measures

2-4

2.4 Unresolved Issues

2-16

2.5 Cumulative Issues

2-17

2.6 Program Planning and Implementation

2-18

3

SUMMARY OF PUBLIC PARTICIPATION

3-1

4

COMMENT LETTERS AND RESPONSES

4-1

5

TEXT CHANGES AND ERRATA

5-1

6

DISTRIBUTION LIST

6-1

FIGURES

4-1

Areas of Critical Environmental Concern (ACEC) in theImperial Valley

4-14

4-2

Seasonal Flow Variations (1976-1982)

4-14

4-3

Lower Colorado River Flow Schematic

4-14

4-4

Major Canals in the Imperial Valley

4-18

TABLES

2-1

Potential Water to be Conserved

2-3

2-2

Potential Significant Adverse Impacts and Mitigation Measures

2-5

4-1

Comment Letters and Responses

4-2

5-1

Text Changes and Errata

5-2

5-2

Additions to Bibliography

5-1


CHAPTER 1

INTRODUCTION

 

The Draft Environmental Impact Report (EIR), Proposed Water Conservation Program and Initial Water Transfer, Imperial Irrigation District (referred to herein as the District or the IID), was released for public review in April 1986. This final programmatic EIR and focused EIR on the initial transfer of 100,000 AF/year represents the finalization of the draft document mentioned above and has been prepared in accordance with the California Environmental Quality Act (CEQA) regulations and District guidelines for the preparation of Environmental Impact Reports. This final EIR (FEIR) is to be used in conjunction with the draft EIR (DEIR). Modifications to the draft documents have been made in response to public and agency comments received during the draft review periods. The Executive Summary is presented in Chapter 2 as a revision of the Executive Summary presented in the DEIR. Chapter 3 summarizes a public hearing that was held on April 28, 1986, to receive public input on the DEIR. Copies of comment letters received from persons, organizations, and public agencies during the DEIR review period are found in Chapter 4 of this volume, and the responses to these comments have been made by modifying the contents of the draft document, as necessary. Responses to specific comments are also listed in Chapter 4, along with the comments. A summary table of minor changes to the DEIR and a table listing additions to the bibliography are presented in Chapter 5. Chapter 6 is a listing of agencies and persons to whom the DEIR was distributed.

The Water Requirements and Availability Study for Imperial Irrigation District, Final Report, Parsons Water Resources, Inc. (1985a in the DEIR) is included by reference in this FEIR as Appendix A. It is available for review at the following locations:

(1) IID Executive Office
1284 Main Street, El Centro

(2) IID Division Offices:

138 South 8th, Brawley
310 Imperial Avenue, Calexico
140 West Main, Calipatria
1285 Broadway, El Centro
567 Pine Avenue, Holtville
130 South Imperial Avenue, Imperial
198 East 3rd, Westmorland

(3) IID Public Affairs Officer

333 East Barioni Blvd., Imperial

(4) Public Libraries:

Brawley
Calexico
E1 Centro
Imperial
Holtville
Indio

This final programmatic EIR has been prepared in accordance with State CEQA Guidelines, Section 15168. This document also contains a focused project EIR on the initial transfer in accordance with Section 15161. Several participants requested specific and detailed information on impacts and mitigations appropriate to a site-specific project development. This document, as a long-range planning tool, is not intended to address project-specific details; they will be addressed in CEQA reviews for each water conservation program element. These CEQA reviews will be performed before any program element is implemented and may determine that a specific program element:

(1) Is categorically exempt.

(2) Should be the subject of a focused EIR.

(3) Is not going to have environmental impacts and, therefore, merits adoption of a Negative Declaration.

However, this FEIR has been revised and expanded to provide additional information where available and pertinent to the scope of a programmatic EIR and project EIR as a result of comments received on the DEIR.

Impact discussions in this document have been made as specific as possible within the limitations of CEQA guideline provisions on speculative impacts contained in Section 15145. A programmatic document is prepared so that an overall view of the concept may be evaluated in relation to cumulative impacts, which are likely to be missed on a "piecemeal" basis over a long period of time. As such, project-specific CEQA reviews will be prepared consistent with the programmatic document.

Impacts derived from the implementation of the initial transfer of 100,000 AF are analyzed and discussed in more detail in both the body of this FEIR and in the responses to comments. The basic conclusion of these analyses is that no direct impact can be identified.

The programmatic EIR portion of this document will be used in connection with later activities and with subsequent CEQA reviews for specific water conservation projects. This use is consistent with the state and the District CEQA guidelines. Subsequent CEQA reviews will be prepared that will incorporate this programmatic document by reference, and they will focus on issues relevant to the site-specific action at appropriate levels of environmental review.

Mitigation measures are discussed on a conceptual and policy basis in this document. Such conceptual guidelines will be used in implementing water conservation projects. Specific mitigation plans will be covered in CEQA reviews. With each CEQA review undertaken pursuant to the program, additional mitigations may be feasible and available. All mitigations will require a review for applicability and feasibility within the context of environmental documents prepared for specific elements of the plan. Mitigations that are feasible and within the jurisdiction of the agencies to impose can be made conditions of leases, permits, or contractor specifications.


CHAPTER 2

EXECUTIVE SUMMARY

 

This Environmental Impact Report (EIR) has been prepared by the Imperial Irrigation District pursuant to section 21151 of the California Environmental Quality Act (CEQA). The EIR addresses both the impacts of an expanded water conservation program proposed by the IID and the initial transfer of 100,000 AF/year of conserved water. The alternatives being considered for these proposals are the "no-program" alternative and the "no-initial-transfer" alternative.

2.1 PROJECT BACKGROUND

The IID was organized in 1911 to deliver Colorado River water to lands within the Imperial Valley, California, for agriculture, domestic, industrial, and other beneficial uses. Water flows through the Imperial Valley in a complex system of delivery canals, laterals, and drains. Agricultural drainage water flows into the New and Alamo Rivers and directly to the Salton Sea, which is a sink for all drainage in the Imperial Valley. The IID currently serves approximately 500,000 acres of agricultural land with a baseline water demand of about 2.77 million AF/year. The District has present perfected rights to 2.6 million AF/year. Under the California Seven-Party Agreement, the IID has a right to beneficial use of a portion of the 3.85 million AF/year of Colorado River water available to California's agricultural agencies in accordance with the priorities established in that agreement.

Past and present water conservation programs implemented by the District have resulted in the conservation of an estimated 138,000 AF/year of water through a series of structural, operational, administrative, and educational programs, including canal lining, seepage recovery systems, regulatory reservoirs, and administrative actions.

2.2 PROGRAM DESCRIPTION

The IID proposes to implement an expanded water conservation program designed to conserve up to 496,000 AF/year of water through a series of conservation projects and measures. Under this program, the District is considering the potential transfer of up to 250,000 AF/year of conserved water to other water agencies outside the IID that are capable of receiving the water through the existing Colorado River Aqueduct. The initial transfer of 100,000 AF/year would be the first step in this process and would provide payments to the IID to permit implementation of the proposed conservation program.

In addition to the previous conservation efforts (138,000 AF/year), the proposed expanded conservation program would conserve an additional 358,000 AF/year of water through the following measures:

(1) Concrete lining an additional 550 miles of lateral canals.

(2) Concrete lining the All-American Canal from Pilot Knob Check to Drop No. 1, the East Highline Canal, the Vail Canal and Rositas Canal.

(3) Constructing up to 150 reservoirs of varying sizes that are dispersed throughout the IID.

(4) Installing improved flow-monitoring structures at approximately 1,500 metering and recording stations throughout the District to measure flow at key points in the system.

(5) Replacing approximately 2,000 old gates in the District's lateral system that often leak.

(6) Constructing operational discharge recovery systems made up of cross canals located at the end of each lateral.

(7) Automating the IID's facilities using existing microwave communications systems, local microcomputers at the head of each lateral, and associated monitoring devices.

(8) Establishing a land leveling program (i.e., farm grading for better distribution of irrigation water) to augment current private programs.

(9) Establishing a tailwater pumpback program for reuse of on-farm tailwater on a farm-by-farm basis.

(10) Installing salinity control through a reverse-osmosis 270-mgd capacity desalination plant with a brine stream of approximately 27-mgd (concentration of approximately 10,000-mgd total dissolved solids); or other measures, if needed, to mitigate against higher salinity.

(11) Miscellaneous projects.

In addition to the foregoing measures, three components have been identified that, although not directly conserving water, are essential to the total program:

(1) Power offset measures

(2) Groundwater reserve facilities

(3) Environmental mitigation projects

The amounts of additional water projected to be conserved through the program described above are given in Table 2-1.


Table 2-1 - Potential Water to be Conserved

==========================================================================
Method
Estimated Amount
Conserved
(AF/year)
----------------------------------------------------------------------------------------------------------------------------------

Canal Lining

All-American Canal:

Pilot Knob to Drop No. 1

51,000

East Highline Canal

46,000

Vail Canal

2,000

Rositas Canal

2,000

Laterals

35,000

Subtotal

136,000

Reservoirs

35,000

Improved flow-monitoring structures

36,000

Non-leak gates

14,000

Recovery of operational discharge

30,000

System automation

27,000

Land leveling

20,000

On-farm tailwater recovery systems

20,000

Desalination plant

30,000

Miscellaneous methods

10,000

Total

358,000

_______________________________________________________________________________________

Source: Parsons, 1985a.

===========================================================================


It is anticipated that program implementation could begin in 1987 and that the initial transfer of water could begin in 1987-1988. The program described above is estimated to be accomplished over a 12- to 14-year period at a current estimated capital cost of $600 million, exclusive of additional capital cost required for environmental cultivation. Revenue received for transfers of conserved water would finance water conservation improvements and measures, fund environmental projects and mitigation studies, and assist in maintaining reasonable water rates within the District. A more detailed project description, including a preliminary implementation schedule, is presented in DEIR Chapter 2.

2.3 SIGNIFICANT ENVIRONMENTAL EFFECTS AND MITIGATION MEASURES

The first 100,000 AF/year of water transferred would not have any significant environmental effect because this water has already been conserved and is not entering the IID's system. A discussion follows of the degree to which the conservation of greater amounts of water may have significant environmental impacts.

Adverse and beneficial environmental impacts predicted to occur as a direct or indirect result of the conservation program are discussed in DEIR Chapter 4. The following subsections present a summary discussion of (1) significant beneficial impacts, and (2) significant adverse impacts and mitigation measures.

2.3.1 SIGNIFICANT BENEFICIAL IMPACTS

The significant beneficial impacts that will result from the expanded conservation program are primarily economic and will result in increased water availability and improved quality:

(1) Water conservation, to the extent reasonable, will enable the District to ensure fulfillment of the mandate of California laws and the state constitution with respect to making beneficial use of water.

(2) Water conservation will ensure that the IID's water availability is increased by conserving 500,000 AF/year, transferrming only 250,000 AF/year, and developing a groundwater reserve for use in high demand years. This additional water could be available to support Imperial Valley growth.

(3) Reduction in the current level of the Salton Sea will reduce penalty payments by the IID to landowners impacted by the existing high sea level. 

(4) Stimulation of the regional economy will occur through the local expenditure of $300 million on construction and $20 million/year on operations and maintenance (O&M) expenditures.

(5) Water rights will be preserved through the conservation of 358,000 AF/year of water. 

(6) Providing concrete lining and other feasible and cost-effective improvements to delivery systems and water drainage, including improved flow-monitoring devices, reduced mechanical eradication of hydrilla (aquatic vegetation), and installation of salinity control measures - all designed to enhance water conservation and irrigation practices - will improve and reduce farm production costs in the Imperial Valley. 

(7) An outside source of funding for the transfer of up to 250,000 AF/year of conserved water will be obtained in order to finance the expanding Water Conservation Program.

Overall, there will be a regional economic benefit from local expenditures made for the Water Conservation Program. These expenditures, plus the cost savings realized through the measures listed above, will have a direct beneficial impact on the economy of the Imperial Valley. In addition to the benefits just discussed, additional expenditures can be expected to be made for environmental mitigation measures. 

The benefits just enumerated do not take credit for what may be potentially one of the most important economic benefits - saving the Salton Sea. The IID intends to participate in a comprehensive study of the Salton Sea with the objective of preserving this resource. If a solution for the declining value of the sea results from the proposed District study, property values around the sea would significantly increase, businesses would expand, and county tax revenues would increase accordingly.

2.3.2 POTENTIAL SIGNIFICANT ADVERSE IMPACTS AND MITIGATION MEASURES 

Table 2-2 lists the significant environmental impacts and mitigation measures for the proposed programs. Not all proposed mitigation measures are feasible, guaranteed, or even possible because the IID may need approval from state and federal agencies, which may or may not be granted. The IID recognizes that several mitigation measures could, if implemented, reduce impacts to an insignificant level. A discussion is given in FEIR Table 5-1 (see insert for DEIR pages 5-2 and 5-3).


Table 2.2 &endash; Potential Significance Adverse Impacts and Mitigation Measures

==========================================================================
Impact
Mitigation Measures
_______________________________________________________________________________________

WATER RESOURCES

1. Lower elevation and higher salinity of the Salton Sea. This is a significant adverse impact.

Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state, and local agencies must be involved.

This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to participate in and support a task force currently being organized by the California Secretary of Resources to examine solutions to the impacts.

2. Increased salinity and decreased flows in New and Alamo Rivers and drains. Decreased potential for beneficial use of this water. This is a significant adverse impact.

Effects on terrestrial and aquatic biota will be miti-gated (see discussion for Impacts 7 and 14 in this table). Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state, and local agencies must be involved. This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to participate in a study to determine how to mitigate the impacts effectively.

3. Large increase in salinity of Alamo River near the international border (potential location of brine discharge) if the desalination plant is constructed and the brine stream is disposed of in the Alamo River. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measure adopted.

Use alternative means to dispose of brine such as land disposal.

4. Increased pollutant concen-trations (e.g., pesticides, herbicides and other agricultural chemicals) in the New River at the outlet by as much as 20%, and increased pollutant concentration in the Alamo River by as much as 50%, at some locations, assuming present pollutant load. This is a significant adverse impact.

Mitigation measures will be developed by the California Regional Water Quality Control Board (CRWQCB) (Colorado River Basin Region) when SB 1745 is implemented, in addition to possible authorization of funds for further studies and cleanup. The IID will participate in studies addressing mitigation for the New and Alamo Rivers. This impact will not be mitigated to an accept-able level unless there is action by others as described.

5. Potential contamination of groundwater by land disposal of desalination brine. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

Locate or design disposal areas to minimize impacts to aquifers, as required by waste discharge orders of CRWQCB.

TABLE 2-2 (CONTD)

==========================================================================

Impact
Mitigation Measures

_______________________________________________________________________________________

6. Increased salinity (of up to 10 mg/L) of irrigation water from the Colorado River prior to construction and operation of the planned desalination plant. This is significant adverse impact at will be mitigated to an insignificant level with the mitigation measures adopted.

The desalination plant is the currently defined mitigation measure; however, continuing studies may define other, more cost-effective alternatives

TERRESTRIAL BIOLOGY

7. Loss and degradation of wetlands/riparian habitat with change in species composition and abundance. Includes impacts to Yuma clapper rail and black rail habitats. This is a significant adverse impact but will be mitigated to an insignificant level with the mitiga-tion measures adopted.

a. Assist in maintaining an adequate amount of the existing habitat with drainage water and/or fresh water.
b. Offset by enhancing existing habitat elsewhere or creating new replacement
c. Assist in maintaining a Yuma clapper rail enhancement program.

8. Damage to wetlands/riparian habitats with stress to wildlife due to construction and operational activities. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

d. Restrict construction disturbance to as small an area as possible, avoiding sensitive areas.
e. Regulate traffic and noise in sensitive areas.
f. Use standard dust-control practices.
g. After considering sensitive habitats during site selection (see mitigations for Impact 9 in this table), restrict opera-tional activities to minimize stress to wildlife.

9. Displacement of wetlands/riparian habitats due to facilities placement and land disposal of brine. Destruction of Yuma clapper rail habitat and displacement of Yuma clapper rail (endangered species) and black rail. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

h. Prohibit construction in sensitive habitats.
i. Offset by enhancing existing habitat elsewhere or creating new replacement habitat.
j. Assist in a Yuma clapper rail enhancement program.
k. Locate or design disposal area(s) to minimize impacts to sensitive areas, as required by waste discharge orders of CRWQC8.

10. Wildlife mortality. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Restrict traffic to light wildlife-use areas and use adequate caution.
b. Construct burro deer escape structures in lined canals, where required, to facili-tate escape. Construct ramps or roads across canals at burro deer crossings. Provide a source of water for burro deer and other wildlife, e.g., passive water collection devices using perforated tile water collection designs such as those currently in use in the Imperial Valley.
c. Restrict construction areas and traffic from sensitive habitats.
d. Use bird deterrents to exclude birds from brine ponds, if constructed. Construct ponds in low-use bird areas.

11. Increased uptake of pollutants into food chain through New and Alamo River wetlands and riparian habitats. This is a significant adverse impact.

Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state, and local agencies must be involved. This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to participate in a study to determine how to mitigate this adverse environmental impact effectively.

12. Change in species composition and abundance, toxicity, and/or mortality due to increased salinity in Alamo River. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measure adopted.

Dilute sensitive habitats with drainage water and/or fresh water.

13. Reduction in migratory bird--use areas within Imperial and Riverside Counties, which are part of the Pacific flyway. This is a significant adverse impact but will be mitigated to an insignificant level.

Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state and local agencies must be involved. This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to participate in a study to determine how to effectively mitigate this adverse environmental impact. Given that solutions are developed for the problem of river pollution and higher Salton Sea salinity, the water quality impacts of the IID's Water Conservation Program will be eliminated, along with impacts to the Pacific flyway.

TABLE 2-2 (CONTD)

==========================================================================
Impact
Mitigation Measures
_______________________________________________________________________________________

14. Decrease in terrestrial biota use of the Salton Sea aquatic and riparian habitats. This is a significant adverse impact but will not be mitigated to an insignificant level by the mitigation measure adopted.

Although wetlands/riparian habitats in rivers, wildlife refuges, canals, and drains will be enhanced (see mitigation for Impact 7 in this table), this impact to Salton Sea habitats will not be mitigated to an acceptable level unless there is action by others as described in item 1, above. It should be noted, however, that the IID is committed to participate in and support a task force currently being organized by the California Secretary of Resources to examine solutions to the impacts.

AQUATIC BIOLOGY

15. Accelerated loss of biota and fishery in the Salton Sea, including the desert pupfish (endangered species). This is a significant adverse impact but will not be mitigated to an insignificant level by the mitigation measures adopted.

Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state, and local agencies must be involved. This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to partici-pate in and support a task force currently being organized by the California Secretary of Resource to exam-ine solutions to the impacts.

16. Change in canal aquatic species composition and abundance. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Create up to 10 backwater areas along the East Highline Canal and up to 5 along the All-American Canal.
b. Use standard construction practice to reduce turbidity.

17. Increased uptake of pollutants into the aquatic food chains of the New and Alamo Rivers. This is a significant adverse impact.

Mitigation measures will be developed by the California Regional Water Quality Control Board (CRWQCB) (Colorado River Basin Region) when SB 1745 is implemented, in addition to possible authorization of funds for further studies and cleanup. The IID will participate in studies addressing mitigation for the New and Alamo Rivers. This impact will not be mitigated to an acceptable level unless there -is action by others as described.

SOCIOECONOMIC

18. Accelerated loss in recreational value of the Salton Sea. This is a significant adverse impact.

Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state, and local agencies must be involved. This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to participate in and support a task force currently being organized by the California Secretary of Resources to examine solutions to the impacts.

19. Accelerated loss in resort and property values near the Salton Sea. This is a significant adverse impact.

Because the IID does not have the economic ability, authority, or jurisdiction to carry out mitigation for this impact, all concerned federal, state, and local agencies must be involved. This impact will not be mitigated to an acceptable level unless there is action by others as described. It should be noted, however, that the IID is committed to participate in and support a task force currently being organized by the California Secretary of Resources to examine solutions to the impacts.

SOILS

20. Soil erosion and deposition from water action during construction.This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measure adopted.

Plan proper drainage to prevent erosion due to runoff from compacted, barren, and disturbed soil surfaces.

21. Soil erosion and deposition from wind action during construction. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Minimize soil erosion due to wind action from off-road vehicle use in construction areas by limiting all vehicle traffic and construction activity to the authorized ROW and through paving, oiling, graveling, or watering.
b. Cover stockpiles of excavated materials.
c. Prevent erosion due to wind action during major land leveling operation by watering soil surfaces periodically.
d. Minimize grading activities during dry windy conditions.

TABLE 2-2 (CONTD)

==========================================================================
Impact
Mitigation Measures
_______________________________________________________________________________________

GEOLOGY AND SIESMICITY

22. Changes to existing physiography and topography during construction. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measure adopted.

Conduct all construction grading to meet minimum requirements of the Uniform Building Code or local ordinances.

23. Increased risk of seismic ground-motion-induced damage to canal system. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Use existing or conduct detailed geologic investigations of active fault zones.
b. Use geologic report to site and design facilities. Map all foundation excavations for critical structures by a California engineering geologist.
c. Complete emergency repair plans to mitigate damage to canal system in the event of an earthquake--induced rupture. Include plans to cut off water to canal system to minimize spillage.

INFRASTRUCTURE

24. Permanent increase in electric power demand and loss of capacity to generate hydropower. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Construct new and/or retrofit existing hydropower facilities.
b. Purchase additional power outside the IID.

25. Potential threat to public safety from falling into lined canals. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

Construct escape structures (see mitigation measure b for Impact 10 in this table).

CULTURAL RESOURCES AND PALEONTOLOGY

26. Loss or disturbance of cultural resources. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Compile inventory of all known resources in areas potentially affected and delineate areas that have been surveyed to federal standards [66- to 98-ft (20- to 30-m) transect intervals].
b. Conduct intensive surface survey of all areas in item 26a that have not been adequately studied, and evaluate significance of visible sites and the potential for buried sites
c. Where avoidance of significant resources is not feasible, prepare miti-gation plan, obtain concurrence of state/federal agencies, and consult with appropriate Native American communities.
d. Implement mitigation plan, which may involve mitigation by scientific data recovery, i.e., excavation, analysis, and report.
e. Provide archaeological monitoring during subsurface construction activities in sensitive areas as defined in item b, above. If cultural resources are encountered, they will be evaluated and effects mitigated as provided in the mitigation plan..

3. Loss of fossils and associated scientific data. This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measure adopted.

Monitor construction in highly important areas. If fossils are found in any area during construction, stop construction until qualified paleontologist has examined remains, deter-mined their importance, made recommendations recording further mitigation, and initiated/completed one or more of the following measures: remove fossils, conduct no further mitigation, survey/monitor immediate area.

AIR QUALITY AND NOISE

4. Long-term increase in noise in vicinity of desalination plant (if constructed). This is a significant adverse impact but will be mitigated to an insignificant level with the mitigation measures adopted.

a. Use low-noise-producing electrical motor pumps and equipment as much as feasible in the desalination plant complex.
b. Shield equipment as necessary, using barriers and enclosures.

 


2.4 UNRESOLVED ISSUES

Although the IID is committed to the implementation of its expanded Water Conservation Program using sound environmental procedures, there are significant adverse environmental impacts that the District cannot solve alone. These impacts fall into two general categories: 

(1) Salton Sea 

Although the IID is committed to participate in and support an interagency task force to examine solutions to the Salton Sea problem, any study will require the support of all concerned governmental agencies. Without a solution being implemented, the decline of the sea will continue with or without implementation of an expanded water conservation program. The Salton Sea's fishery and other associated recreational uses would be reduced at an accelerated rate. 

(2) New and Alamo Rivers

The discharges from agricultural, domestic and industrial sources, in particular those from Mexico, will become increasingly damaging to the New and Alamo Rivers as the District's conservation program reduces drain flows and their dilution effects. The loss of habitat and biota will be mitigated to an acceptable level by the District; however the aesthetic value may be diminished. In addition, the uptake of pollutants by aquatic biota and wetland violation would increase and more pollutants would enter the food chains of the New and Alamo Rivers.

The District believes that there is a real possibility, through joint efforts with other agencies that all or a major part of the Salton Sea can be stabilized at an elevation and salinity that would preserve the fishery. 

To this end the District is committed to participate in and support an interagency study to determine ways that the competing demands on the Salton Sea may be balanced and managed to maximize the benefits. This study would be coordinated with other ongoing efforts and would focus on legal, environmental, institutional, fiscal and technological issues.

The loss of the Salton Sea s fishery may be delayed to some extent if (1) a fish hatchery were established and operated, and (2) if the Salton Sea's fishery were managed as a put-and-take fishery. These measures would counteract the reduced fish production caused by high salinity. The normal lead agency for implementing this mitigating measure is the California Department of Fish and Game. This measure could be implemented, if it is found to be feasible by the Salton Sea task force. Although this is a temporary solution it may be useful until a more permanent solution is found. 

Increased pollutant uptake by the food chain is another consequence of reduced flows. The principal concern is with the New River, which carries a large amount of pollutants from Mexico. Not all of these pollutants have been identified much less quantified. This problem has been recognized; however the solution has been evasive because of funding problems unresolved international issues, and questions of priority. Mitigation measures are currently being developed by the CRWQCB (Colorado River Basin Region). Bill and bond issue funds (pending) are also possible means for further study and cleanup. To create a better understanding of the nature of the pollution and an assessment of the public health risks, the IID would be willing to be one of the participants in a comprehensive water quality analysis of the New and Alamo Rivers if funds are received for the transfer of water. With this better understanding an appropriate solution can be developed. If this pollution problem is ultimately solved, the impacts from pollutant uptake would be greatly mitigated. 

The foregoing discussion concentrates on mitigating measures that can be implemented in coordination with other agencies and organizations if funds are received for the transfer of water. The District has proposed specific actions that others any take to mitigate significant adverse impacts and has made specific commitments about its own role and contribution.

2.5 CUMULATIVE IMPACTS

The analysis of cumulative impacts made full use of the available data including the Imperial County Genera1 Plan (1985). In particular the Water Requirements and Availability Study (WRAS) (which was incorporated in toto by reference in the DEIR) made extensive use of the county's planning documents to define current urban land use, develop future growth trends, and make population projections. Use of the County General Plan was essential to the development of projected demands that would be made on the IID. All of the data available in the county's planning documents was, therefore, available and used to arrive at cumulative impacts of the IID's Water Conservation Program. 

In addition to local planning data, the California State Clearinghouse Computer was searched in March 1986 for notices filed in accordance with CEQA for the period 1984 through 1986 (to date) to identify projects that could generate cumulative impacts in association with the IID's expanded Water Conservation Program. Projects in Imperial County and eastern Riverside County were included in the review. From that search, 22 projects were identified; four projects were for residential and/or commercial developments, three for recreational vehicle parks, seven utility expansion projects, five industrial developments, two geothermal projects, and one freeway interchange modification. 

All of these projects are within the framework established by local plans and policies, which were taken into account when projections of water demand were formulated (Parsons, 1985a). No significant cumulative impacts at a program or regional level other than those identified as deriving from the expanded water conservation plan have been identified.

Any projects of significant scope with the potential to create localized cumulative impacts will be included in each focused EIR prepared for the IID's Water Conservation Program. The projects listed and discussed above include all that were identified for this program EIR and focused EIR for the initial transfer of 100,000 AF/year of Conserved water. 

2.6 PROGRAM PLANNING AND IMPLEMENTATION

Further planning for and implementation of the expanded water conservation program will be a dynamic process. This will be evidenced by continuing refinement and modification to program elements, schedules and environmental mitigation measures brought about by additional technical studies and planning, incorporation of environmental mitigation measures, and consultations with other agencies, concerned individuals, and organizations. 

During 1985, the District intensified its water conservation planning activities in order to synthesize the program's definition to the point where the cumulative range of the program's environmental impacts could be reasonably addressed. This activity resulted in several planning reports being published: the IID's current Water Conservation Plan, the Water Requirements and Availability Study (WRAS), and the Water Transfer Study (WTS). Collectively, those three reports provided the necessary program framework and identified a number of projects and measures that could be considered for implementation by the IID's Board of Directors.

During 1986, the program EIR and the focused EIR on the initial transfer will be completed. In addition, the District plans to prepare detailed implementation plans to facilitate budgeting and program execution. These plans will identify project details, schedules, applicable environmental criteria and permit activities, design, procurement, construction, commissioning and startup, and cash flow requirements. 

Numerous activities and approvals are required and will be accomplished prior to implementing the specific projects and measures that are included in the Program Implementation Plans. The District's Board of Directors will ensure that:

(1) A CEQA review is conducted for each project or water conservation measure.

(2) All necessary approvals and permits are obtained from the appropriate governmental and regulatory agencies.

(3) The necessary funds are available.

(4) Each specific project or water conservation measure is approved by the IID's Board of Directors before implementation.


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