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Border 2012

RECORD OF DECISION
International Boundary and Water Commission
South Bay International Wastewater Treatment Plant
Interim Operation
San Diego, California

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I. INTRODUCTION

In a 1994 Final Environmental Impact Statement (FEIS) and Record of Decision (ROD), the U.S. Environmental Protection Agency (EPA) and the U.S. International Boundary and Water Commission (USIBWC) decided to construct the 25 million gallon per day (mgd) secondary South Bay International Wastewater Treatment Plant (IWTP) and South Bay Ocean Outfall (SBOO). The purpose of the project was to provide new wastewater control facilities to safeguard the public health, environment, public beaches, water quality, and economy of San Diego, California.

Construction of the IWTP and SBOO is currently ongoing. In the 1994 FEIS and ROD, the agencies decided to phase construction of the IWTP, with advanced primary facilities being constructed first, in order to expedite treatment of flows from Tijuana, Mexico. Those flows would otherwise continue to pollute the river, estuary, and coastal waters in the U.S.No decision, however, was made to operate the plant as an advanced primary facility. The 1994 ROD established that if any level of treatment, other than secondary is discharged from the IWTP, an additional NEPA document would be completed. When the agencies decided to propose to operate the IWTP prior to completion of the secondary treatment phase, this Supplemental Environmental Impact Statement (SEIS) was prepared to evaluate the proposed project changes to operate the plant as an advanced primary treatment facility on an interim basis. In addition, EPA and USIBWC are currently preparing a second SEIS to re-evaluate secondary treatment processes for the IWTP; this SEIS will be completed in the summer of 1998.

This Draft SEIS for Interim Operation of the IWTP was prepared by EPA and the USIBWC. A Notice of Availability was published in the Federal Register on September 6, 1996. Written comments were received through October 21, 1996. A public hearing to receive comments on the Draft SEIS was held at Southwest High School in San Diego on October 7, 1996. EPA and the USIBWC reviewed and considered the oral and written comments submitted for the Draft SEIS. EPA and the USIBWC concluded, based upon this review, that no additional alternatives needed to be considered with respect to the proposed project and that no substantive new analyses or major revisions to the Draft SEIS were necessary. The Final SEIS, consisting of copies of the letters of comment received, EPA and USIBWC's written responses, a transcript of the oral comments received at the public hearing, an errata sheet and attachments, was circulated for public review and comment from December 6, 1996 to January 6, 1997. No additional substantive comments were received to the Final SEIS. For purposes of filing, the Draft SEIS is adopted and incorporated into the Final SEIS with the corrections indicated in the errata sheet.

This Record of Decision has been prepared in accordance with 40 CFR 1505.2 to document EPA and USIBWC's decision on the proposed interim operation of the IWTP.The decision of the EPA and USIBWC is based on the SEIS developmental process (40 CFR 1502) and public involvement (40 CFR 1500).

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II. DECISION

The EPA and the USIBWC have decided that Alternative 6, the preferred alternative identified in the SEIS, shall be authorized and constructed. Alternative 6 consists of the interim operation (1997-2001) of the 25 mgd (1,095 LPs) International Wastewater Treatment Plant (IWTP) as an advanced primary facility. This decision to operate the IWTP on an interim basis is planned to be implemented in the following manner:

  1. Initially, up to 13 mgd of sewage from Tijuana would continue to be sent directly from Pump Station One to the City of San Diego's Point Loma Wastewater Treatment Facility for treatment and disposal via San Diego's emergency connection. In order to maximize the amount of flows the emergency connection can accommodate during high flow periods, the IWTP would treat and store up to 2 mgd. During low flow periods of the day, this effluent would then be sent through the emergency connection to the Point Loma facilities for further treatment and disposal.
    In this situation, the IWTP would provide only limited treatment since the effluent would receive advanced primary treatment at the City of San Diego's Point Loma Wastewater Treatment Plant.
  2. Once construction of the detention facility is completed in November 1997, the IWTP would treat to the advanced primary level sewage from Tijuana and then store the treated effluent for ultimate disposal through the emergency connection. The IWTP would be treating these sewage flows to the advanced primary level in order to control odors in the detention basin.
  3. If Mexico constructs a parallel pumping and conveyance system in their country prior to the completion of SBOO, up to 25 mgd (1,095 LPs) of advanced primary effluent from the IWTP may be discharged to this system on an interim basis.
  4. When SBOO is completed, 25 mgd (1,095 LPs) of advanced primary effluent will be discharged at a point 18,700 feet (5. 7 km) offshore at a water depth of 93 feet (28 m) in U. S. waters.Use of the emergency connection may be discontinued once SBOO becomes operational.

Alternative 6 will ultimately collect and treat, to advanced primary treatment levels, sewage from the City of Tijuana, Baja California, Mexico that cannot be handled by Tijuana's existing pumping, conveyance and treatment system and would otherwise flow into the U. S.as untreated sewage. This alternative substantially reduces the risk of adverse impacts to public health and to the ecology of the Tijuana River Valley Estuary that would be caused by the flow of raw sewage into the United States during dry weather conditions. If peak flows occur prior to completion of the SBOO that cannot otherwise be discharged to the emergency connection, those flows will be treated to the advanced primary level and discharged to the Tijuana River.

The 1994 FEIS and ROD recommended the following major project elements:

During the interim operation of the IWTP, all sludge that is generated would be disposed of by Mexico in Mexico pursuant to Treaty Minute 283. In addition, a decision whether to implement chlorination/dechlorination for the discharge through SBOO will be based upon data received from monitoring of receiving waters. Effluent discharged to either the Tijuana River or to new conveyance facilities in Mexico will not be chlorinated.

This decision is based on a review of the 1994 FEIS for the IWTP and Ocean Outfall Facilities Project; the 1996 Draft and Final SEIS for Interim Operation of the IWTP and associated technical documents prepared for the project; a National Pollutant Discharge Elimination System (NPDES) permit and compliance order issued by the California Water Quality Control Board for the San Diego Region; and the California Coastal Commission's Finding of Consistency with the Coastal Zone Management Act.

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III. ALTERNATIVES AND CONSIDERATIONS BALANCED IN MAKING THE DECISION

In arriving at the decision to operate the IWTP during the interim period, the alternatives of No Action and four alternative plans for operation and discharge of treated effluent were formulated and evaluated in detail. The array of alternatives considered was based on: 1) U. S.agreements with Mexico (USIBWC Minute 270 and USIBWC Minute 283); 2) existing and planned facilities in Mexico and the U. S.; and 3) a forecast of future sewage generation in Mexico, prepared by EPA and USIBWC in consultation with Mexico. To assist in the evaluation of the alternatives, specifically the effects to U. S.ocean waters from the discharge of untreated sewage and treated effluent to the shoreline in Mexico and treated effluent through SBOO, a study modeling shoreline and ocean discharges was prepared by Parsons Engineering Science. A hydraulic model of stream flow in the Tijuana River was also prepared by Boyle Engineering to assess impacts of river discharges to the Tijuana estuary.

Alternative 1: No Action

If the agencies had selected the No Action Alternative, the IWTP would not be operated until the secondary treatment works and the ocean outfall was completed, in accordance with the May 1994 ROD. Flows from Tijuana would continue to be conveyed from Pump Station One through Tijuana's existing system to its treatment works at San Antonio de los Buenos, with flows in excess of 17 mgd (745 LPs) discharged untreated to nearshore ocean waters. Flows to Pump Station One would also be conveyed through the existing emergency connection to the City of San Diego's system. Peak flows of raw sewage in excess of the combined capacity of Pump Station One and the emergency connection would be discharged into the Tijuana River in the U. S.via Stewart's Drain. Based upon the USIBWC/EPA flow projections, these untreated flows are estimated to be between 1. 7 mgd (75 LPs) average daily flow and 4. 6 mgd (202 LPs) seasonal high (wet weather) daily flow in 1997 and between 5. 6 mgd (245 LPs) to 9. 7 mgd (425 LPs) in 2001.Untreated flows discharged to nearshore ocean waters in Mexico from Tijuana's wastewater treatment system would increase from 19. 7 mgd in 1997 to 22. 9 mgd (1,008 LPs) by the year 2001.

This alternative was expected to result in dry weather flows of sewage into the U. S., polluting the Tijuana River, the Tijuana estuary and coastal areas from the international border northward to Coronado. While dry weather sewage flows of 1. 1 mgd (48 LPs) were forecast to occur in 1996, Mexico has been able to contain the flows during the year. The assumptions used in the forecast are conservative, in order to provide the highest degree of protection for the Tijuana River valley. Based upon system capacities and future growth in Mexico, as summarized in the flow forecasts, EPA and USIBWC were concerned that under this alternative dry weather sewage flows would occur in the river during the interim period and prior to the completion of SBOO. This contamination is a human health and safety risk from waterborne disease and disease bearing vectors, and would have impacts on water quality. It would have adverse consequences for the Tijuana estuary, a national estuarine research reserve and habitat for endangered species. Sewage contamination reduces agricultural productivity in the Tijuana River valley, limits the public use and enjoyment of coastal areas and state and local parks and has substantial negative impacts to the local economy. The continuing discharge of untreated sewage is unacceptable to local residents of the valley and surrounding communities and has been the reason for emergency declarations by the state and local jurisdictions.

Alternative 2: Operate the IWTP with Discharge to the Emergency Connection

The IWTP would be operated to provide treatment before completion of the ocean outfall. Mexico would continue to convey flows up to 36. 6 mgd (1,603 LPs) of untreated sewage from Pump Station One to San Antonio de Los Buenos. Excess flows from Mexico at rates up to 13 mgd (569 LPs) during peak hour flow periods of the day would be directed to the emergency connection to the City of San Diego's Point Loma facility. It is estimated that approximately 2 million gallons of effluent could be detained within the primary treatment trains at the IWTP during high-flow periods of the day, to be sent to the emergency connection during low flow periods. Flows in excess of the capacity of Pump Station One and the emergency connection would be treated at the IWTP and discharged into the Tijuana River in the U.S.

During average dry weather flow conditions, no discharges to the river of treated effluent would occur until 1998, when 0. 6 mgd (26 LPs) is forecasted; however, treated flows could be discharged to the river during seasonal high peak flow conditions as early as 1997. If SBOO is not available for effluent discharge, the treated flows discharged to the river are estimated to be 1. 4 mgd (61 LPs) average daily flow and 4. 7 mgd (206 LPs) seasonal high flow in 1999.Year 2001 flows would range between 3. 6 mgd (158 LPs) and 7. 5 mgd (329 LPs).

Operation of the IWTP would increase the capacity of the existing Mexican and U. S.system by adding approximately 2 mgd (88 LPs) storage of peak flows for discharge during off-peak hours. It would also provide advanced primary treatment for flows in excess of the existing system capacity (25 mgd average [1,095 LPs], 75 mgd [3,285 LPs] peak) that would otherwise flow untreated into the U. S. Treatment would reduce biological oxygen demand, solids, and levels of some organic, toxics or metals in the sewage; which would be beneficial relative to the discharge of untreated sewage. Although this would have some beneficial effects relative to untreated sewage, discharge of treated effluent to the river would have significant adverse environmental consequences to human health and safety, the estuarine and marine ecology, water quality, and recreational uses in the Tijuana River valley. Discharge of advanced primary treated effluent from the IWTP to the river is controlled by a cease and desist compliance order issued by the RWQCB for interim operation of the IWTP.

Alternative 3: Operate the IWTP with a Detention Basin

The IWTP would be operated as an advanced primary plant. In addition, a 5. 5 million gallon (20,900 m3) detention basin for effluent storage would be constructed at the IWTP site to provide flow equalization for diurnal peak flows. The detention basin would be lined, with a depth of 10 to 15 feet (3. 0 to 4. 6 m) and covering an area of 1 to 2 acres (0. 4 to 0. 8 ha). Treated flows would be stored within the detention basin to be released to the emergency connection during off-peak hours. If the capacity of the Mexican system, as well as the emergency connection and detention basin would be exceeded, then the excess treated flows would be discharged to the Tijuana River in the U.S.

It is anticipated that no untreated or treated flows would be discharged to the Tijuana river prior to the scheduled completion of the ocean outfall in 1998. From 1998 to 2001, even without the SBOO, we estimate there would be no flows to the Tijuana River during average day flows. However, during seasonal high flow days, there would need to be a discharge of 0. 7 mgd (31 LPs) in the year 2000 and 2. 0 mgd (88 LPs) in 2001. Discharge of treated effluent from the IWTP to the Tijuana River would reduce the level of pollutants in the waste stream as noted above, but would still have significant adverse environmental consequences to the Tijuana River valley, estuary and nearshore coastal waters. Such discharges are prohibited under the NPDES permit for the operation of the IWTP.

During the time that the IWTP would be operated under Alternative 3, Mexico would operate its existing pumping and conveyance system at its current capacity. As the treatment works at San Antonio de los Buenos can only treat approximately 17 mgd (748 LPs) of the wastewater conveyed to it, approximately 19. 7 mgd (867 LPs) to 22. 9 mgd (1,004 LPs) would be discharged, untreated, to the shoreline in Mexico 5. 6 miles (9 km) south of the international border. Modeling of the dilution and transport of this discharge conducted by Parsons Engineering Science has indicated that coastal waters in the U. S.may exceed California Ocean Plan standards for coliform, which could constitute a risk to health and safety.

Alternative 4: Operate the IWTP with New Pumping and Conveyance in Mexico

A new pumping and conveyance system would be constructed by Mexico as a parallel backup facility for the existing Mexican conveyance system, with a capacity of 50 mgd (2,150 LPs), to convey flows from Pump Station One to the discharge point at ca¤on San Antonio de los Buenos in Mexico.These backup facilities would provide an additional pumping and conveyance system and would allow maintenance to be performed on the existing facilities once the SBOO is operational. During the interim period, the IWTP would treat flows up to 25 mgd (1,095 LPs) from Tijuana. Once treated, the effluent would be sent to Tijuana via the new pump station and conveyance pipeline for surf discharge in Mexico, near the San Antonio de los Buenos treatment plant. The existing pumping and conveyance system to the treatment works in San Antonio de los Buenos would continue to operate.

With the additional pumping and conveyance capacity in Mexico, all of the sewage flows from Tijuana could be conveyed south to the point of discharge at ca¤on San Antonio de los Buenos. No discharge of untreated or treated flows to the Tijuana River in the U. S.is anticipated. With the IWTP operating at 25 mgd (1,095 LPs) and the treatment works at San Antonio de los Buenos continuing to operate at 17 mgd (748 LPs), no discharge of untreated sewage to the shoreline in Mexico would occur until the year 2000 (1. 0 mgd [43 LPs]) under average flow conditions.

Use of the additional pumping and conveyance facilities would only be on a short term basis, however, and it is not environmentally preferred to the use of the SBOO for discharge. The volume of wastewater discharged to the shoreline in Mexico, even though treated to advanced primary standards, would result in significant adverse impacts to U. S.coastal waters. Modeling of the shoreline discharge for this alternative predicted exceedances of bacteriological standards north of the international border.This is due to the relatively low level of initial dilution from shoreline discharge and seasonal currents transporting the effluent northward. In addition, Mexico has indicated that the additional pumping and conveyance system is not an acceptable alternative to the SBOO under the agreements in USIBWC Minute 283.

Alternative 5: Operate the IWTP with Discharge to SBOO

The South Bay Ocean Outfall is currently under construction. Once completed in 1998, up to 25 mgd (1,095 LPs) of advanced primary effluent from the IWTP could be discharged to the ocean. No discharge to the Tijuana River would be necessary. Even with continued operation of the Mexican treatment works at San Antonio de Los Buenos, 2. 9 mgd (128 lps) of untreated effluent would be discharged to the shoreline in 1998 and 9. 6 mgd (420 lps) would be discharged in 2001.

Interim discharge of treated effluent is regulated under a cease and desist order issued by the RWQCB. To assess the effects of the interim discharge of advanced primary effluent through the SBOO, Parsons Engineering Science conducted modeling of the discharge from SBOO to generate predicted concentrations of bacterial coliform and California Ocean Plan Table A and Table B constituents. These results were compared with the California Ocean Plan limits. It was found that no bacteriological exceedances would result, and potential exceedances for only two constituents (HCH and PAH) were likely. It was also predicted that with the reduced discharge to the shoreline in Mexico, no exceedances of Ocean Plan Table A or B constituents in U.S. waters would result. However, bacteriological exceedances could still occur at the international border and the mouth of the Tijuana River as a result of the shoreline discharge in Mexico.

The SEIS includes an evaluation of interim effluent disposal options and specific evaluation of probable environmental consequences of discharge through the ocean outfall. After evaluation of the SEIS and supporting technical studies of oceanographic conditions, initial dilution, outfall design, marine organisms and beneficial uses of the ocean waters affected, the ocean outfall is the least environmentally damaging interim effluent disposal alternative. Discharge of the IWTP effluent through the SBOO will be environmentally preferred to discharge to the Tijuana River or to discharge to the shoreline in Mexico. However, since SBOO is not scheduled for completion until 1988, discharges of untreated sewage to the Tijuana River are predicted to occur in the EPA/USIBWC forecasts.

Alternative 6: Operate the IWTP with Phased Discharge

The previous alternatives have been evaluated as stand-alone alternatives to taking no action through the year 2001. However, none of these stand-alone alternatives would be as effective as Alternative 6 in preventing a discharge to the Tijuana River over the entire interim period. Alternative 6 combines these individual alternatives in a phased approach which results in a more environmentally preferred alternative.

The phasing scheme would begin with Alternative 2, operate the IWTP to treat and store up to 2 million gallons (7,600 m3) of peak flows from Tijuana with discharge during off-peak periods to the emergency connection. When it appears that the total average dry-weather flows from Tijuana or higher seasonal high peak flows would result in discharge of treated effluent from the IWTP to the Tijuana River (estimated to occur in 1997 or 1998), then either Alternative 3 (Operate IWTP with Detention Basin) or Alternative 4 (Operate IWTP with New Conveyance to Mexico), if available, could be implemented. Either of these two alternatives could provide a means to avoid discharging treated effluent from the IWTP into the Tijuana River. When the SBOO is completed, all treated effluent from the IWTP would be discharged through the SBOO. Once the SBOO is available, neither the detention basin nor the additional conveyance system in Mexico are planned to be used.

The IWTP will be operational by the spring of 1997. The 5. 5 million gallon (20,900 m3) lined detention basin would be available by November 1997.The new Mexican pumping and conveyance system, is expected to take 15 months to complete once agreement with Mexico has been reached and BECC certification has been completed. These Mexican facilities are not expected to be available for use before April 1998. The SBOO is currently under construction and would not be available for use before the summer of 1998.

The impacts of the phased alternative would be equal to or less than any of the stand-alone alternatives over the interim period from 1997 to 2001. Alternative 6 would reduce the potential for discharge of treated effluent to the Tijuana river because facilities will be used as they become available in order to avoid discharge of treated effluent into the Tijuana River. However, the USIBWC/EPA flow projections are estimates, and the flows sent from Mexico could exceed the discharge capacity before these new facilities (detention basins, SBOO) are available. If this occurs, discharge of treated effluent into the Tijuana River will be unavoidable and the adverse environmental impacts will be similar to those discussed for Alternative 2.

Alternative 6 is the environmentally preferred alternative that most effectively achieves the basic purpose of the project, which is to assist in safeguarding the public health, environment, public beaches, water quality, and economy of San Diego by treating and disposing of sewage from Tijuana, Mexico, which would otherwise flow untreated into San Diego, California. Alternative 6 incorporates all practicable means to avoid environmental harm while achieving the project purpose.

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IV. MEANS TO AVOID OR MINIMIZE ADVERSE ENVIRONMENTAL EFFECTS

All practicable means to avoid or minimize adverse environmental effects have been incorporated into the recommended plan for interim operation. The USIBWC is responsible for the completion and monitoring, as applicable, of the mitigation measures associated with Alternative 6. These measures are:

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V. DISCUSSION OF ISSUES AND FACTORS

The following issues were considered by the agencies in reaching our decision on interim operation:

Future Flows from Mexico

EPA and USIBWC forecasted increases in sewage generated in Tijuana through the year 2001, in consultation with Mexico. The forecasts were based upon actual flows measured in 1995 and a 4. 8 % annual increase in flow, due to growth in the population and industry and to improvements made to the collection system to prevent untreated flows from entering the Tijuana River in Mexico. The results of these forecasts predicted discharges of untreated sewage into the U. S. beginning in 1996 with Mexico operating its system at its current capacity. While the predicted dry weather discharges did not occur in 1996, the forecast indicated that discharges of sewage are highly likely to occur in the near term.

Comments were received that questioned the forecasted volumes that the IWTP would receive from Mexico; specifically that the IWTP would receive 25 mgd (1,095 LPs) of flows as soon as it became operational and that the effluent would be discharged to the Tijuana River. The evaluation of alternatives in the SEIS was based upon Mexico continuing to maintain the current volume of flows in their system and the continued use of the emergency connection until the SBOO becomes operational. Mexico has provided assurances that they will continue to maintain flows at their current levels until the SBOO is operational.

Discharges of IWTP Effluent to the Tijuana River

The SEIS evaluated interim operation alternatives that could result in the discharge of treated effluent to the Tijuana River. The preferred alternative was selected because it was less likely to result in discharges of treated effluent to the river and because it provided the environmentally superior method for discharge of treated effluent. Discharges to the river are also subject to a cease and desist order under the NPDES permit to operate the IWTP. However, a clear preference was expressed by members of the public and jurisdictions that discharge of treated effluent to the river would be preferable to allowing raw sewage to enter the Tijuana River. If failures of the Mexican system were to occur, or if the flows during the interim period (prior to completion of SBOO) are higher than forecasted, discharge of IWTP effluent to the Tijuana River may occur. The NPDES permit includes a cease and desist compliance order in this eventuality. Actions to be taken include prompt notification of affected individuals, jurisdictions and agencies and monitoring of the river and estuary to identify the consequences of the discharges.

New Pumping and Conveyance in Mexico (Return to Sender)

Mexico has proposed to construct additional pumping facilities, a force main and conveyance canal that would essentially parallel the facilities from Pump Station One to the San Antonio de Los Buenos Wastewater Treatment Plant. These new facilities are intended to provide increased reliability and improve the opportunities to perform maintenance on the existing system, rather than to increase capacity. The new facilities would be funded in part by the EPA and implemented in cooperation with the Border Environment Cooperation Commission, which will be requested to certify the project.

These new facilities were included in the alternatives considered in the SEIS, because they may become operational prior to completion of the SBOO and could provide a means for interim discharge of IWTP effluent. During the public involvement process for the SEIS, there was strong support expressed for the earliest possible implementation of these new facilities. Use of these facilities for IWTP effluent, if available prior to SBOO would only be for a short term period, however. Mexico has indicated that these facilities would notbe an acceptable alternative to the SBOO and could not be used for discharging IWTP effluent other than on an interim basis. Modeling of the discharge of IWTP effluent showed that discharge through the SBOO to be environmentally preferred to the discharge from the new conveyance canal discharging to the shoreline in Mexico.

Chlorination of Effluent

Modeling of coliform levels for both secondary and advanced primary discharges through SBOO indicated chlorination may not be required to meet ocean plan standards.The effluent discharged through SBOO will only be chlorinated/dechlorinated if monitoring results of receiving waters indicate noncompliance with the coliform standard as regulated by the California Ocean Plan. Ocean monitoring once SBOO is operational is required by the NPDES permit issued by the RWQCB.

Chlorination of the effluent without dechlorination is not considered feasible for interim discharge either to the river or to new conveyance facilities in Mexico. Residual chlorine and byproducts are highly toxic and could cause adverse effects to the biota of the receiving waters. Even with dechlorination, trace residual chlorine is a concern for receiving waters.

Toxic Source Reduction Program in Mexico

Comments were received from the public which indicated a concern about a toxic source reduction program in Mexico to limit the amount of pollutants ultimately treated at the IWTP. Currently, the State Water Resources Control Board and the City of San Diego are coordinating with Mexico to assist them in developing a toxic source control and reduction program for industries that discharge wastewater to the Tijuana sewer system. In addition, the NPDES permit for the IWTP requires a headworks analysis to be completed in order to identify the maximum concentrations of pollutants that could be present in the influent to the IWTP and still be able to meet California Ocean Plan standards. This analysis will assist Mexico in prioritizing their toxic source reduction efforts.

Modeling of Shoreline and Ocean Discharge

Comments were received from the public that questioned the methodologies used in preparing the modeling and analysis of the effects of discharge of untreated sewage or treated effluent to the ocean shoreline in Mexico and through the South Bay Ocean Outfall. This modeling and analysis was prepared as a technical study for the SEIS. It was a key analytic component of the SEIS and was made available under separate cover to interested parties during the review period. The comments from the public suggested that the modeling could not have been conducted as presented, based upon deficiencies in the base data and analytic models used, that the study was seriously flawed and that previous current studies had indicated that there were no northerly trending currents along the shoreline south of the international border.

EPA, USIBWC, the State Water Quality Control Board and the City of San Diego had reviewed the methodologies used prior to release of the Draft SEIS. The technical study was also independently reviewed by the National Ocean Service for the National Marine Fisheries Service during the public review period. EPA also contacted the author of one of the analytic models used in the study whose use was questioned by the public for clarification.

After consideration of the challenges made to the adequacy of the analysis by the public, EPA and USIBWC have found that their comments were based upon misunderstanding of the data and methodologies used in the modeling and analysis and that it is technically sound and appropriate in scope to evaluate the effects of the alternatives considered in the SEIS. Specific responses to the alleged deficiencies are provided in the responses to comments from the public.

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VI. COMPLIANCE WITH ENVIRONMENTAL REQUIREMENTS

Discharge of advanced primary effluent is not authorized under the federal Clean Water Act. The operator of the IWTP will comply with a discharge permit and compliance order issued by the RWQCB. The recommended plan, Alternative 6, is in compliance with other applicable environmental requirements.

Section 402 of the Clean Water Act established the National Pollution Discharge Elimination System (NPDES) permitting program. As part of the NPDES permit for the IWTP and ocean outfall, a baseline ocean monitoring plan is being implemented and will collect data for a minimum of two years prior to the release of effluent from the ocean outfall. Also as part of the NPDES operation permit, effluent discharges (at a flow rate of 25 mgd [1,095 LPs]) released from the outfall will comply with the effluent limitations established under the permit by the RWQCB. The NPDES permit prohibits discharges of effluent from the IWTP to the Tijuana River. If such discharges were to occur a cease and desist order (96-52) must be complied with. The order requires that monitoring of the river and estuary be conducted.

The California Regional Water Quality Control Board has waived section 401 water quality certification for this project.

The California Coastal Commission finds the project consistent to the maximum extent practicable with the resource protection policies of the California Coastal Act and the Coastal Zone Management Program.

Through informal consultation under Section 7 of the Endangered Species Act the Fish and Wildlife Service has determined that interim operation of the IWTP and Outfall Facilities are not likely to jeopardize the continued existence of the endangered least Bell's vireo, California brown pelican, California least tern, and the threatened coastal California gnatcatcher. Further, it was the Services' determination that the project would not adversely affect the endangered pacific pocket mouse. And finally, based on the information provided in the hydrogeology report prepared for the project, no adverse modification to designated critical habitat for the least Bell's vireo should result.

VII. SUMMARY

In conclusion, we find that the recommended plan and environmentally preferred alternative, Alternative 6, interim operation of the IWTP with phased discharge represents the course of action which best serves the overall public interest and complies with the National Environmental Policy Act. Even though this action is not consistent with water quality objectives, we find that interim operation of the IWTP would result in a net environmental benefit as opposed to discharge of untreated sewage from Mexico into the Tijuana River or nearshore coastal waters in Mexico. Our decision takes into account the direct, indirect, and cumulative impacts from the project. The project includes all practicable means to avoid or minimize environmental harm while providing for the collection and treatment of sewage from Tijuana, Baja California, Mexico.

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VIII. Attachments

  1. NPDES Permit
  2. Cease and Desist Order 96-52
  3. Draft River Discharge Monitoring Program
  4. Coastal Consistency Determination

Note: These documents, while not on the Web site, may be requested in hard copy from Elizabeth Borowiec at borowiec.elizabeth@epa.gov

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