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Interim Operation–Supplemental Environmental Impact Statement

DRAFT

Supplemental Environmental Impact Statement
for the International Boundary and Water Commission
International Wastewater Treatment Plant
Interim Operation

September 6, 1996

EXECUTIVE SUMMARY

Scope of the SEIS

The South Bay International Wastewater Treatment Plant (IWTP) and South Bay Ocean Outfall (SBOO) are currently under construction as identified in the Final Environmental Impact Statement (FEIS) and Record of Decision (ROD) signed in May 1994. The purpose of the project is to provide new wastewater control facilities to safeguard the public health, environment, public beaches, water quality, and economy of San Diego, California. In conjunction with actions taken by Mexico, this project would minimize dry-weather flow of untreated sewage from the municipality of Tijuana, Baja California, Mexico, into the United States. Currently, such flows cause chronic and substantial pollution in the Tijuana River valley, national reserve estuary, and coastal areas used for agriculture and public recreation and is designated critical habitat for federal and state listed endangered species. In the 1994 ROD, the federal agencies decided to build a secondary wastewater treatment facility and ocean outfall.

The purpose of this Supplemental Environmental Impact Statement (SEIS) is to evaluate proposed project changes to operate the plant as an advanced primary treatment facility on an interim basis. Unless the facility is operated during this period, dry-weather flows of sewage could continue to pollute the river, estuary, and coastal waters in the U.S. This Interim Operation SEIS evaluates alternatives for using the IWTP as an advanced primary treatment works until alternatives to secondary treatment are evaluated and the SBOO is completed. Alternatives for providing secondary level treatment of sewage at the IWTP will be the subject of an additional SEIS.

The development of the IWTP and SBOO and the proposed interim operation of the facilities is a collaborative effort of the U.S. and Mexico through the International Boundary and Water Commission, U.S. Section (USIBWC), U.S. Environmental Protection Agency (EPA), State Water Resources Control Board, Regional Water Quality Control Board, and the City of San Diego.

Purpose and Need for Action

The Tijuana River and nearshore coastal waters of the United States have been contaminated with raw sewage since the 1930s. Due to the physiographic setting and proximity of the city of Tijuana to the United States untreated sewage flows into the United States via the Tijuana River or through north-draining canyons and gullies. Untreated sewage is also discharged to nearshore ocean waters in Mexico, 5.6 miles (9 km) south of the international border, which may affect the quality of ocean waters in the U.S. The contamination has been the result of Tijuana's rapid and constant population growth coupled with a lack of corresponding sewerage infrastructure.

From 1980 to 1991, however, there were sustained perennial flows of wastewater in the Tijuana River. Flow data measured by the USIBWC indicated that the average wastewater flow into the U.S. was 13 million gallon per day (mgd) (569 liters per second [lps]) in 1990. In 1991 Mexico installed a collector in the Tijuana River to divert up to 13 mgd of dry-weather flows to the sewage system. More recently, estimates are that in 1993, 3 mgd (131 lps) of wastewater was in the river and in 1995, 1 mgd (44 lps).

These untreated sewage flows have caused chronic quarantines of public beaches along the south San Diego coastline (Border Field State Park, City of Imperial Beach, Silver Strand State Beach, and City of Coronado) and substantially and adversely affected the residents of the Tijuana River valley and the environmental quality of the Tijuana River estuary, a National Estuarine Research Reserve.

The USIBWC/EPA have developed estimates of future sewage generation from Tijuana through the year 2001 based upon an annual growth rate of 4.8 percent. The estimates indicate that if no action is taken, the capability of Mexico's current sewage collection system would be exceeded by 1.1 mgd (48 lps) to 3.5 mgd (153 lps) by the end of 1996. By the planning horizon year of 2001, the system's capacity would be exceeded by 5.6 mgd (245 lps) to 9.5 mgd (416 lps). Unless action is taken, these untreated sewage flows would enter the U.S. and pollute the Tijuana River and nearshore coastal areas.

Additionally, the capacity of the San Antonio de los Buenos treatment facility in Mexico is currently being exceeded and untreated flows of sewage are being discharged to the shoreline in Mexico. The volumes of untreated sewage being discharged at the shoreline are estimated to be 19 mgd (832 lps) in 1996 and would increase to 22.9 mgd (1,003 lps) by 2001.

The IWTP will be operational as an advanced primary treatment works before secondary treatment is available or the ocean outfall is operational. The IWTP can detain and treat peak flows in the interim period that may otherwise be discharged untreated to the Tijuana River and nearshore ocean waters in Mexico. These flows, in excess of the Mexican pump station or treatment works capacities, could be diverted for treatment to advanced primary levels at the IWTP, beginning in 1997. Therefore, consideration of the earliest possible operation of the IWTP is of urgent necessity.

Current and Planned Facilities in Mexico and the U.S.

The chronic contamination has been acknowledged in numerous declarations by local, state, and federal legislative bodies and commissions and has been the subject of international agreements between the U.S. and Mexico. To address this international problem, the U.S. and Mexico have considered various alternatives for increasing the quantity and level of sewage treatment and discharge options. The U.S. and Mexico subsequently entered into binational agreements (Minute Nos. 270 and 283) to construct in both countries new facilities to collect, treat, and dispose of sewage.

Mexico's Facilities

The Stage I facilities proposed under Minute No. 270 substantially comprise the current facilities in Mexico. These facilities include:

Most of these facilities, including the San Antonio de los Buenos treatment works (Module 1, but not Module 2), have been completed and are being operated by Mexico.

In October 1991, Mexico completed construction of and operates a diversion structure in the Tijuana River in Mexico, about 325 feet (100 m) upstream of the international border. A mixture of river flows and sewage can be captured and diverted to Pump Station One. During dry weather, up to 13 mgd (569 lps) of sewage-contaminated flows can be pumped from the concrete, low-flow river channel into Mexico's collection system and to Pump Station One if capacity is available. Wet-weather and storm flows are allowed to pass through to the U.S., even if contaminated with sewage.

U.S. Facilities

Emergency Connection

An emergency connection between Pump Station One and the City of San Diego's South Metro Interceptor sewer has been in existence since 1966. This connector consists of a 30-inch (0.76 m) sewer trending north from Pump Station One to the 36-inch (0.91 m) San Ysidro Interceptor; the San Ysidro Interceptor ties into a 42-inch (1.09 m) segment of the South Metro Interceptor. The existing emergency connection can accept up to 13 mgd (569 lps) peak flows, which are treated and disposed of at the City's Point Loma advanced primary treatment plant and ocean outfall.

The availability of the emergency connection to accept flows from Mexico is limited and will not continue indefinitely into the future, however. The emergency connection is also susceptible to being washed out by flood flows in the Tijuana River.

South Bay International Wastewater Treatment Plant and Ocean Outfall

In keeping with Minute No. 283, the EPA and the USIBWC circulated an EIS and signed an ROD in May 1994 for new federal facilities to treat sewage. Construction has begun of a 25 mgd (1,095 lps) federal treatment works known as the South Bay IWTP and the SBOO, a 200-foot-deep (65 m) tunnel connecting with a wye diffuser located 18,700 feet (5.7 km) offshore in 93-foot-deep (28 m) ocean waters to dispose of the treated wastewater.

The IBWC project includes the following major elements:

The headworks are designed to handle up to 100 mgd (4,380 lps) including screening and degritting. The primary treatment facilities are designed to treat average daily flows of 25 mgd (1,095 lps) with peak flows up to 75 mgd (4,117 lps) during high flow days. The activated sludge facilities are designed to treat a constant flow of 25 mgd (1,095 lps).

Wastewater flows from east Tijuana are collected via the Tijuana wastewater collection system and conveyed to Pump Station One, where they are mixed with wastewater from central Tijuana. From Pump Station One, wastewater will be directed to the IWTP in the United States or San Antonio de los Buenos in Mexico. Wastewater flows from the Playas de Tijuana, Matadero (Smuggler Gulch), and Laureles (Goat Canyon) pump stations in Mexico will continue to be routed through the Mexican conveyance system to the San Antonio de los Buenos treatment plant. The outfall is designed to carry a maximum average daily flow of 174 mgd (7,621 lps) and a peak daily flow of 333 mgd (14,585 lps) to enable use of the outfall by both the IWTP and future City of San Diego Otay and South Bay treatment works. The outfall is currently scheduled to be completed by June 1998.

The advanced primary treatment works and ocean outfall are scheduled to be completed in 1997 and 1998, respectively. Once completed, the IWTP and ocean outfall would treat and dispose of sewage from Mexico that may otherwise enter the U.S. untreated to safeguard the public health, environment, public recreation, water quality, and economy of San Diego and nearshore coastal waters.

Alternatives Considered

EPA and USIBWC are considering operating the IWTP as an advanced primary treatment works prior to the completion of the ocean outfall and the secondary treatment process trains to minimize the risk of discharges of raw sewage or treated effluent into the Tijuana River. In considering this action, alternatives for the discharge of advanced primary effluent during the interim period prior to completion of the ocean outfall and secondary treatment at the IWTP have been identified. The IWTP could begin operation prior to completion of the ocean outfall with interim discharge to the emergency connection, Mexico, the Tijuana River, or a combination of these.

The potential effects of discharge of advanced primary effluent through the outfall to the year 2001, the interim period, are also being evaluated to allow for further consideration of the design and construction of the secondary treatment facility.

Evaluation of Alternatives

The alternatives being considered by EPA and USIBWC are related to the proposed operation of the IWTP as an advanced primary treatment works for a limited period of time. Environmental effects from the construction and operation of the IWTP as a secondary treatment works and land and ocean outfall were considered in the 1994 FEIS. For interim operation, no major additional facilities in the U.S. would be required, although Mexico may construct additional pumping and conveyance facilities in Mexico.

Estimated Sewage Flows from Mexico

Future Tijuana wastewater flow estimates were developed by USIBWC/EPA based upon flow data collected by IBWC at the emergency connection and the main wastewater conveyance canal in Tijuana during February to December, 1995. These flows include all wastewater generated in Tijuana except the uncollected flows that spill into the Tijuana River or north-draining canyons. Total Tijuana flows were projected through the year 2001, as a worst-case scenario for completion of the SBOO and other facilities. These flow projections were used to estimate the potential for discharge of untreated sewage to the river and, given the existing treatment capacity at San Antonio de los Buenos, the assumed untreated discharges that could occur at the shoreline in Mexico. The projections also assume continued use of the emergency connection to Point Loma.

Because of the limitations associated with the data available on past flow conditions and the uncertainties in growth rate for the Tijuana sewage, the USIBWC/EPA considers their flow projections to be rough estimates. Overall, USIBWC/EPA tried to be conservative in their assumptions and interpretations of available data, but actual flows could be higher or lower than different from the projections, especially by 2001.

Modeling of Effluent Discharge Effects

To assess the impacts to ocean water quality, marine biota and public health from discharge of treated and untreated effluent to the shoreline in Mexico and of advanced primary effluent through the ocean outfall, Parsons Engineering Science has modeled the effects of the discharges including coliform concentrations, dissolved oxygen, and transport (dilution) of organic and inorganic constituents. The modeling was based upon current data collected during the Tijuana Oceanographic Engineering Study, which covered both Mexican and U.S. waters surrounding the SBOO. The USIBWC/EPA flow estimates for Tijuana sewage generation were used and applied to the alternatives under consideration for the years 1996 and 2001. To provide a conservative analysis, the seasonal high flow rates were used, which provide a worst-case analysis. The models provide a screening level analysis for water quality effects for the shoreline and outfall discharges. The assumptions used for current conditions, effluent quality, and flow rates are all conservative estimates. As such, the model results are not definitive predictions of the actual concentrations that would result from the discharges once the IWTP or outfall is operational.

For purposes of the EIS, the model results are compared to the State Ocean Plan as a threshold of significance. This should be understood as a tool in evaluating alternatives and not as a determination of compliance or noncompliance with standards during operations.

Alternative 1: No Action

In accordance with the May 1994 ROD, the IWTP would not be operated until the secondary treatment works are completed and the ocean outfall is operational. 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 1.1 mgd (48 lps) average daily flow and 3.0 mgd (131 lps) seasonal high daily flow in 1996 and between 5.6 mgd (245 lps) to 9.7 mgd (425 lps) in 2001. Untreated flows discharged to nearshore ocean waters in Mexico would reach 20 mgd (876 lps).

Alternative 2: Operate IWTP

The IWTP would be operated to provide advanced primary treatment before completion of the ocean outfall. The IWTP would treat up to 25 mgd (1,095 lps) average daily flow of untreated sewage from Mexico. Mexico would continue to convey flows up to 38 mgd (1,664 lps) of untreated sewage from Pump Station One to San Antonio de Los Buenos and excess flows up to 13 mgd (569 lps) (during peak flow periods of the day) to the emergency connection to Point Loma. Treated flows would be returned from the IWTP to the emergency connection. It is possible that a small amount of effluent could be returned from the IWTP to Pump Station One during low-flow periods of the day, but the emergency connection would be the primary discharge point for the IWTP effluent.

During periods of peak flows, effluent treated at the IWTP that cannot be discharged through the emergency connection would be discharged into the Tijuana River in the U.S. These treated flows are estimated to be between 1.4 mgd (61 lps) average daily flow in 1999 and 4.7 mgd (206 lps) seasonal high flow. Year 2001 flows would range between 3.6 mgd (158 lps) and 7.5 mgd (329 lps).

Alternative 3: Operate IWTP with Detention Basin

The IWTP would be operated as an advanced primary plant, as in Alternative 2. 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 and wet-weather peak flows. The earthen 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 Pump Station One or the emergency connection during off-peak hours. If the capacity of the Mexican system, 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. If the SBOO were not available, there would be no flows to the Tijuana River during average day flows through the year 2001; 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.

Alternative 4: Operate IWTP with New Conveyance to 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 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 placed into service.. 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 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.

No discharge of untreated or treated flows to the Tijuana River in the U.S. is anticipated. No discharge of untreated sewage to the shoreline in Mexico would occur until 1999 with average flow conditions.

Alternative 5: Operate IWTP with Discharge to SBOO

The South Bay Ocean Outfall is currently under construction. Once completed in 1998, 25 mgd (1,095 lps) of advanced primary effluent from the IWTP would be discharged to the ocean. No discharge to the Tijuana River or through the emergency connection would be necessary.

Alternative 6: Phased Alternative

The previous alternatives have been evaluated as stand-alone alternatives to taking no action through the year 2001. It is also reasonable to evaluate the use of these individual alternatives in a phased approach.

The logical phasing scheme would begin with Alternative 2, operate the IWTP to detain up to 2 million gallons (7,600 m3) of flow and treat additional flows from eastern Tijuana as needed with discharge to the emergency connection. When it appears that the total average dry-weather flows from eastern Tijuana or higher seasonal high peak flows would result in discharge of treated effluent from the IWTP to the Tijuana River (expected by 1997 or 1998), then either Alternative 3 (Operate IWTP with Detention Basin) or Alternative 4 (Operate IWTP with New Conveyance to Mexico) 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 earthen detention basin nor the additional conveyance system in Mexico would be needed to discharge treated effluent from the IWTP.

An additional consideration for Alternative 6 is the time required to construct the facilities. The IWTP will be operational by early 1997. The 5.5 million gallon (20,900 m3) lined earthen detention basin would take 9 months to construct and could be available by September 1997. The new Mexican pumping and conveyance system, is expected to take 15 months to complete once agreement with Mexico has been reached. These facilities are not expected to be available for use until 1998. The SBOO is currently under construction and would not be available for use until the spring of 1998.

The impacts of the phased alternative would be equal to or less than the stand-alone alternatives as analyzed above. The phased alternative would reduce the impacts from discharge of treated effluent to the Tijuana river, since each facility would be used in an attempt to avoid discharge of treated effluent into the Tijuana River. However, the USIBWC/ EPA flow projections are estimates, and the flows sent from Mexico may exceed the discharge capacity before these facilities 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.

Significant Environmental Effects of the Alternatives

The alternatives were assessed for significant environmental effects, including direct, indirect, adverse, and beneficial. The evaluation of alternatives is based upon estimates of future flows from Mexico and sewage characteristics, estimates of both IWTP and San Antonio de los Buenos effluent quality, and modeling of the effects of ocean discharges. In the summary Table S-1, many effects are designated as "potentially significant adverse." This indicates that the future effects can only be estimated within a range of values, within which range significant adverse effects could result. This lack of certainty is unavoidable given the information available.

Preferred Alternative

The goal of the action is to avoid the discharge of untreated sewage and minimize the effects of the discharge of treated effluent to sensitive areas such as the Tijuana River, estuary, shoreline, offshore kelp beds, and active recreation and commercial areas. As discharges from the shoreline in Mexico may affect U.S. coastal waters, the alternative that provides the maximum level of treatment to the greatest volume of sewage prior to discharge, whether the discharge occurs in Mexico or the U.S., would be preferred. However, selection of a preferred alternative is also subject to considerations of environmental effects of the alternatives, cooperation with Mexico, timeliness to implement, and costs.

For the interim operations period, the preferred approach alternative would be to phase alternatives as described for Alternative 6.

Starting with operation of the IWTP in 1997, there would not be a need to discharge treated effluent to the river until 1998, according to the USIBWC/EPA flow projections for average day flows. No additional capital costs would be incurred and discharge of effluent to the emergency connection would not result in adverse impacts to receiving waters in the U.S. However, to avoid discharge of treated effluent to the Tijuana River during seasonal high flows in 1997, and average day flows in 1998 and thereafter to 2001, either the detention basin at the IWTP or new conveyance facilities in Mexico would need to be constructed.

Each of these alternatives avoids discharge of treated effluent to the Tijuana River. The new conveyance facilities in Mexico would probably not be available until the middle of the year 1998, and discharges of treated effluent could occur by that time if the IWTP is operated. The addition of detention basins at the IWTP could be implemented in time (September, 1997) to avoid any discharges of treated effluent to the Tijuana River and does not require additional agreements with Mexico to implement.

Neither of these interim alternatives is environmentally preferred to SBOO, as the discharge of treated effluent at the shoreline in Mexico is not preferable to discharge through the outfall offshore. Under current schedules, the SBOO and the new Mexican conveyance are not scheduled to be available until 1998. Assuming these concurrent schedules, the SBOO would be preferred. However, if the new facilities in Mexico were available and the SBOO is delayed, then the new facilities in Mexico could be used to avoid discharges to the river until the SBOO is available.

Once completed, discharge through the SBOO is the preferred alternative.

Environmental Commitments

The following mitigation measures would reduce or avoid potentially significant effects of several of the alternatives considered. The measures are presented as would be appropriate for each stand-alone alternative. For the preferred phased alternative, the measures would still be necessary, but only for the period of time an alternative is operating as a stand-alone facility. For example, once the SBOO is operational, vector control and estuary monitoring required for Alternative 2 would no longer be necessary.

Alternative 2: Operate IWTP

If treated effluent is routinely discharged during dry weather to the Tijuana River, a monitoring program will be undertaken. The program will monitor changes in water quality using indirect indicators of water source and sewage contamination. These include salinity, dissolved oxygen, temperature, and coliform bacteria. The monitoring program will be initiated prior to discharge of the effluent and will continue through the period that effluent is discharged to the Tijuana River. Reports of the monitoring will be provided to the Regional Water Quality Control Board, Tijuana River National Estuarine Research Reserve, and EPA.

If effluent is discharged to the Tijuana River, the USIBWC, in cooperation with the County Department of Health Services, will monitor the river channel during the dry season to ensure that no ponding of treated effluent occurs within the low-flow channel of the river. If ponding does occur, vector control measures will be implemented.

Alternative 3: Operate IWTP with Detention Basin

If a detention basin is constructed at the IWTP, the earthen basin will be lined with an impermeable liner to avoid percolation of treated effluent to the groundwater. The liner will be included in design specifications for the basin by USIBWC. Site-specific geotechnical investigations will be performed prior to construction of the earthen basin to determine soil characteristics, thickness, and distribution and to develop appropriate soil engineering parameters for the proposed facility. Fault evaluation studies will be performed of mapped fault traces in order to confirm fault locations and activities. In addition, a geologist shall observe excavations during construction to detect the presence of unmapped traces in the general vicinity of mapped fault traces.

Storage of treated effluent in the detention basin may result in objectionable odors. As the basin would only fill during peak hourly flow periods, these impacts would be short term. However, if objectionable odors result, the detention basin would be covered and the air circulated to an odor control device. IBWC will include an odor control system in the design of the detention basin, if this alternative is chosen.

Alternative 4: Operate IWTP with New Conveyance to Mexico

Mexico will conduct design review of the pipeline and pump station as part of its environmental impact assessment and to their construction standards. This design should anticipate the effects of ground shaking and incorporate measures to minimize the risk of failure during seismic events.

If construction of the pipeline is undertaken during the rainy season, Mexico should incorporate erosion controls during any grading to prevent erosion impacts into the U.S.

Alternative 5: Operate IWTP with Discharge to SBOO

Odor control facilities were included in the design for the IWTP. If advanced primary treated effluent is discharged through the SBOO, additional odor control facilities will need to be included at a vent for the energy dissipater located between the plant and the South Bay Land Outfall. The USIBWC will be responsible for ensuring that appropriate odor control facilities are provided for discharge of primary treated effluent through SBOO.

Agency and Public Participation in Decision Making

The SEIS has been prepared to assess the consequences of the alternatives for proposed interim operation of the IWTP. The environmental assessment will be used as an aid in decision making by the USIBWC and EPA in deciding a future course of action. It is only one of a number of considerations in determining a future course of action, however. The SEIS will also be used as an informational document by other federal, state, and local agencies-including but not limited to the U.S. Fish and Wildlife Service, State Water Resources Control Board, California Coastal Commission, and City of San Diego-in fulfilling their jurisdictional responsibilities, permitting activities, or other cooperation in implementing any future actions taken.

The Draft SEIS will be available for public and agency review from September 6, 1996, through October 21, 1996. Requests for information or copies of the SEIS may be directed to Ms. Wendi Shafir at EPA Region IX, Water Division, 75 Hawthorne Street, San Francisco, CA 94105, (415) 744-2059, or Mr. Charles Fisher at the USIBWC San Ysidro Office, 2225 Dairy Mart Road, San Ysidro, CA 92173, (619) 662-7600. Copies of the SEIS and supporting documents have also been made available at local library branches in the vicinity of the project (San Diego, San Ysidro, Imperial Beach, Otay Mesa, and Chula Vista). A public hearing to receive comments to the Draft SEIS has been scheduled for October 7, 1996, at Southwest High School.

USIBWC and EPA will review written comments to the Draft SEIS received during the public and agency review period and oral comments at the public hearing. A Final SEIS will then be prepared, including revisions to the Draft SEIS and responses to comments on the Draft SEIS The Final SEIS will be circulated for an additional 30-day public review period.

The USIBWC and EPA will then prepare a Record of Decision for the action that will include consideration of environmental factors as well as other factors that were important in arriving at a decision.

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