Notice of Preparation

Notice of Preparation For a Draft Environmental Impact Report/Environmental Impact Statement For the Lower Guadalupe River Flood Protection Project

San Jose, California

INTRODUCTION

The Lower Guadalupe River Flood Protection Project (LGRP) is proposed for construction by the Santa Clara Valley Water District (SCVWD) on the Guadalupe River between Interstate 880 and the community of Alviso and on Alviso Slough from the UPRR bridge to the terminus of Alviso Slough with San Francisco Bay in San Jose and Santa Clara, California. The LGRP was authorized by SCVWD to provide flood protection, environmental protection and public access opportunities and will be designed and constructed to ensure that the channel improvements are operated and managed to convey design floodflows in the Guadalupe River from Interstate 880 to the UPRR bridge where Section 104 improvements currently exist and through the bay lands to San Francisco Bay. The LGRP is also incorporating measures to avoid existing fish and wildlife habitat, to protect special status species (e.g. steelhead trout and chinook salmon under the Endangered Species Act, and the Magnuson-Stevens Act, respectively) and to meet conditions for water quality certification under the Clean Water Act.

The SCVWD is the lead agency for compliance with the California Environmental Quality Act (CEQA) and the U.S. Army Corps of Engineers (Corps), San Francisco District, is the lead agency for compliance with the National Environmental Policy Act (NEPA). The intent of the combined EIR/EIS is to describe and evaluate potential effects of the LGRP on environmental resources in the project area. The EIR/EIS will include sufficient information for compliance with both CEQA and NEPA, as well as opportunities for public participation in the planning and decision-making process.

NEED FOR EIR/EIS

The lead agencies, SCVWD and Corps, have determined that the LGRP may have a significant impact on the quality of the human environment and have decided to prepare an EIR/EIS to provide ample opportunity for public disclosure and participation in the planning and decision-making process. The integrated document will include sufficient information for approval of the LGRP and compliance with CEQA and NEPA. The purpose of the draft EIR/EIS process is to develop and assess a recommended plan and alternatives for the LGRP and to avoid and mitigate significant adverse effects on environmental resources. The EIR/EIS will address a reasonable range of alternatives, environmental effects of the alternatives, and compliance with related environmental laws and permits.

PUBLIC PARTICIPATION

A 30-day public scoping period will begin on April 17, 2000, and end on May 17, 2000. Public comment is invited on the proposal to prepare the EIR/EIS, and on the scope of issues to be included in the EIR/EIS. Please submit any comments by May 17, 2000 to the contact address identified below. A scoping meeting is scheduled for May 3, 2000, in San Jose. Concerned persons and organizations are invited to call or write to be included on the mailing list for public meetings or to receive other correspondence concerning the LGRP.

# The scoping meeting on May 3, 2000, will be from 6:00 to 8:30 p.m. at the Silicon Valley Conference Center, 2161 North First Street, San Jose, California 95113.

Availability

• The draft EIR/EIS is expected to be available for a 45-day public review and comment period in fall 2000.

• 
  The final EIR/EIS is expected to be available for a 30-day review period in March 2001.

For Further Information Contact:

Lower Guadalupe River Flood Protection Project
Santa Clara Valley Water District
5750 Almaden Expressway
San Jose, CA 95118-3686
(408) 265-2607 Ext. 2724

or

Robert Smith
U.S. Army Corps of Engineers
(415) 977-8450
rsmith@spd.usace.army.mil

PROJECT DESCRIPTION

Background

The Lower Guadalupe River Flood Protection Project (LGRP) reach is located within the cities of San Jose and Santa Clara, California, between Interstate 880 and the UPRR bridge in Alviso and on Alviso Slough from the UPRR bridge to the terminus of Alviso Slough with the San Francisco Bay. The LGRP reach receives runoff from a highly urbanized region comprising a steep upper watershed, an urban residential and light commercial zone (the upper Guadalupe River), and a significantly developed and encroaching downtown commercial zone. Storm drainage from these areas and from storm water pump flows within the project area is also discharged into the lower Guadalupe River, adding to the runoff volume.

The Downtown Guadalupe River Project, located upstream of the LGRP, is scheduled to be completed by the end of 2002. Once the downtown project is completed, the result will be an increase of peak floodflows that are able to reach the lower river reach. Because the lower Guadalupe River does not currently have the ability to convey the expected design flood event, floodway modifications will be designed and constructed to ensure that the channel improvements are operated and managed to convey the design floodflow with a peak of 20,000 cubic feet per second (cfs) at Alviso.

Study Area Location

The Guadalupe River, located south of San Francisco Bay, drains an area of about 160 square miles into the Bay. The primary project area is located along approximately 6.5 miles of the lower Guadalupe River between Interstate 880 and UPRR bridge in Alviso and approximately 4.0 miles along Alviso Slough between the UPRR bridge in Alviso to the terminus of Alviso Slough with the San Francisco Bay.

Document Scope

This proposed EIR/EIS for the LGRP will support decision making by the SCVWD and Corps to implement the LGRP and ensure compliance with CEQA and NEPA. Potential direct and indirect environmental, social, and economic effects of the alternatives will be evaluated and measures to reduce environmental impacts will be proposed.

Proposed Scoping Process

a. This Notice of Preparation (NOP) initiates the CEQA scoping process whereby the SCVWD and Corps will refine the scope of issues to be addressed in the draft EIR/EIS and identify potential significant environmental issues related to a proposed action and alternatives.

b. Public comment is invited on the proposal to prepare the draft EIR/EIS and on the scope of issues to be included therein.

c. The SCVWD and Corps will consult local, state, and federal agencies with regulatory or implementation responsibility for, or expertise in, the resources in the area of investigation. These include, but are not limited to, the City of Santa Clara, City of San Jose and San Jose Redevelopment Agency; the State Historic Preservation Officer, California Department of Fish and Game, California Environmental Protection Agency, Regional Water Quality Control Boards, State Lands Commission, San Francisco Bay Conservation and Development Commission, and California Department of Transportation; and the U.S. Fish and Wildlife Service, National Marine Fisheries Service, and U.S. Environmental Protection Agency.

d. Meetings with interested persons will be held during the scoping period and after release of the draft EIR/EIS. Coordination with federal and state agencies, tribal governments, and local governments will take place throughout the entire process as necessary.

e. On May 3, 2000, a scoping meeting will be held in the community to describe the LGRP and solicit suggestions, recommendations, and comments to help refine the issues, measures, and alternatives to be addressed in the draft EIR/EIS. Locations, dates, and times of the meeting(s) will be published in a project newsletter, local newspaper(s) or other media, and provided to those persons receiving this notice and those who call or write after seeing a published version.

f. A 45-day period will be provided for public review and comment on the draft EIR/EIS. All interested persons should respond to this notice and provide a current address if they wish to be notified of the draft EIR/EIS. A 30-day public review period will also be provided for review and comment on the final EIR/EIS.

Development and Evaluation of Alternative Plans for the LGRP

The following primary objectives were developed by the study team and were used to develop alternative plans for the project:

• Protect residents and businesses along the lower Guadalupe River subreaches from Interstate 880 to the UPRR bridge in Alviso from floodflows conveyed by the river for a 100-year project life;

• Protect endangered species from floodflows conveyed by the river;

• Preserve and enhance fish and migratory bird habitat to the maximum extent possible;

• Ensure that the project is cost effective and long-term maintenance costs are minimal for a 100-year project life; and

• Provide opportunities for public recreation/open-space amenities.

• Based on application of a set of evaluation criteria, the following alternatives for the project along the lower Guadalupe River were considered to be unimplementable:

• Raising levees. Expanding outboard of the existing levees would encroach into existing buildings, parking lots, and other facilities. Acquiring the land on which to expand would incur additional costs. Expanding inboard would encroach into an extensive wetland area and would raise the design surface-water elevation over the top of many area bridges. This alternative, by itself, does not meet the flood-protection objective of the LGRP.

• Constructing setback levees. This alternative would provide for removal of the existing levees and construction of new levees farther inland; however, it would encroach into existing buildings, parking lots, and other facilities, as well as incur cost of acquiring property. This alternative, by itself, does not meet the flood-protection objective of the LGRP.

• Modifying bridge crossings. This alternative would involve raising bridges and/or removing abutment slopes. With the exception of the eastbound lanes of the Highway 237 bridge, the hydraulic benefit is minimal for all bridges. The cost of raising the Highway 237 bridge and the benefit it provides will be considered as an alternative to or along with a bypass structure at this bridge. This alternative, by itself, does not meet the flood-protection objective of the LGRP.

• Lowering tailwater elevation. The hydraulic benefit of this alternative occurs only at the extreme downstream end of the project. In addition, this alternative, by itself, does not meet the flood-protection objective of the LGRP.

• Paving levees. This alternative would involve paving the inboard portion of levees from the levee top to the toe to smooth out the high-flow surface areas of the channel; however, it would not provide significant increased hydraulic capacity in the downstream subreaches of the project, where capacity is most limited. This alternative, by itself, does not meet the flood-protection objective of the LGRP.

• Diverting floodwater. No discharge location for a diversion has been identified because all adjacent water bodies have associated flooding problems.

• Storing floodwater. Constructing new or modifying existing upstream reservoirs and offstream storage basins was determined to be infeasible, impracticable, and/or only modestly effective. The facilities were estimated to cost between $200 million and $600 million. In the vicinity of the LGRP, the offstream basins would be even more expensive because of the higher cost of land in this area.

• Managing sediment. With the exception of dredging, sediment management programs, by themselves, would not meet the flood-protection objective of the project. Various amounts of sediment removal will be investigated as part of the alternatives analyzed for the LGRP.

• Managing vegetation. Complete removal of vegetation in the lower Guadalupe River would not, by itself, meet the flood-protection objective of the LGRP. Various levels of vegetation management will be investigated as part of the alternatives analyzed in the next phase of the LGRP.

Additional analysis and screening information for these alternative concepts is presented in the Lower Guadalupe River Flood Protection Project Alternatives summary. A final revision of this technical memorandum will be available in May 2000.

Alternatives for the project reach along Alviso Slough are currently being evaluated to determine which alternatives are unimplementable. Please refer to the Alviso Baylands discussion below for a description of the range of alternatives for Alviso Slough.

Alternatives to Be Considered

Five implementable action alternatives for the project along the Guadalupe River to the community of Alviso remain for detailed analysis in the draft EIR/EIS after completion of a rigorous and iterative screening process. The No-Action Alternative is also considered to meet the requirements of CEQA and NEPA, but would not meet the project objective for flood control. Alternatives to be considered are:

• Dredging from Montague Expressway to UPRR,

• Bypass culvert(s),

• Floodwalls, bypasses, and aggressive vegetation management,

• Channel modification, all concrete, from Montague Expressway to UPRR,

• Channel modification, alternate materials, from Montague Expressway to UPRR and

• No-Action Alternative.

The following is a brief description of the range of alternatives that will be evaluated in the draft EIR/EIS for the project along the Guadalupe River to the community of Alviso. The SCVWD has not yet identified a proposed action and will evaluate the environmental impacts of each alternative at an equal level of detail to satisfy the requirements of a CEQA/NEPA joint document. Each of the alternatives would also include an Alviso Baylands component as described below.

Alternative 1: Dredging from Montague Expressway to UPRR

Dredging is a construction method that removes channel-bottom material. To meet the flood-protection objective of the LGRP, the excavation of all or most of the material would be required between the inboard levee toes to a depth of 2.5-5 meters (8.2-16.4 feet) from the Montague Expressway bridge to the UPRR bridge. Initial hydraulic modeling indicates this would increase the capacity of the river sufficiently to convey the design flow within the existing levees, including providing freeboard. Constraints have been identified for this alternative that will need to be evaluated more extensively, including the following:

• impacts on approximately 16.2 hectares (40 acres) of aquatic habitat and 1.21 hectares (3 acres) of riparian forest and other habitat areas;

• regular dredging would be required to maintain the initially dredged cross sections;

• structural modifications may be required to bridge piers that would become more exposed than in their current condition; and

• the Hetch Hetchy Aqueduct and other utilities may need to be relocated.

The order-of-magnitude cost to implement the initial dredging is estimated to be $41 million, which excludes any bridge modifications. Maintenance dredging would be expected to be performed on a scheduled 10-year frequency.

Alternative 2: Bypass Culvert(s)

This alternative would involve the construction of a structure that will convey the flows that exceed the existing capacity of the lower Guadalupe River to a downstream discharge location. The anticipated structure would be a reinforced concrete box constructed within one of the existing levees, with an invert that follows the toe of the levee. It is expected to extend from a location immediately downstream of the U.S. 101 bridge to a location downstream of the UPRR bridge. The dimensions would range from 10 to 15 meters (32.8 to 49.2 feet) wide and between 3.5 and 5 meters (11.5 and 16.4 feet) high. Constraints have been identified for this alternative that will be evaluated more extensively, including:

• constructing the bypass at several bridges, which may involve property acquisition; and

• interferences and the consequent relocations of existing utilities.

The order-of-magnitude cost to implement this alternative is estimated to be $200 million; maintenance costs have not yet been quantified.

Alternative 3: Floodwalls, Bypasses, and Aggressive Vegetation Management

This alternative would involve the construction of 1- to 7-meter-high (3.28- to 23-foot-high) reinforced concrete walls to contain the design flows and provide freeboard. There are a number of configurations that may be appropriate for the LGRP, with the most cost-effective configuration appearing to be one that would maximize the use of the existing right-of-way (ROW) by placing the floodwalls a short distance inside the ROW, along with the removal of the existing levees to provide additional conveyance capacity and the reduction of the floodwall heights.

To allow for maintenance access from the bridge access points to the channel, ramps will be needed over the walls, which in turn will necessitate jogs in the wall and result in a conveyance constriction. This alternative is therefore expected to also include two other measures: aggressive management of vegetation in the channel and construction of up to four bridge bypasses (Highway 237, Tasman, Montague, and Trimble). Constraints have been identified for this alternative that will be evaluated more extensively, including:

• extensive foundation systems that will be required to support free-standing floodwalls, or the use of walls considerably farther inside the ROW that are partially supported by the existing and/or improved levees;

• effects on channel habitat, wildlife movement and escapement during flood events;

• interferences and the consequent relocations of existing utilities, including the Hetch Hetchy Aqueduct;

• modifications to the other bridges that may be required to ensure that freeboard continues across them (i.e., at the floodwall=s termination at each bridge); and

• flood-fighting access would possibly be significantly limited should the entire ROW become dedicated to flood conveyance (i.e., with the walls placed alongside the outside of the ROW, no room is left for access along the ROW that is also outside the flood waters).

The order-of-magnitude cost to implement this alternative is estimated to be $100 million; maintenance costs have not yet been quantified.

Alternative 4: Channel Modification, All Concrete, from Montague Expressway to UPRR

This alternative would involve the excavation of the inboard toe of the existing levees, construction of a vertical or near-vertical wall at the inside of the existing levee, and construction of a concrete apron at the resulting channel bench. This improvement would be constructed between Montague Expressway and the UPRR bridge. In places, it is expected that the wall portion would need to be extended up to provide a short-height floodwall, that a bypass would be required at Highway 237, and that the alternative would include selective removal of sediment. The work for this alternative is not expected to encroach into wetlands areas, as it is anticipated to be entirely constructed above the existing levee toe. Constraints may be due to avoidance of impacts to habitat (primarily ruderal), avoidance of eliminating an escapement area for wildlife during storm events, and impacts to wildlife movements. The order-of-magnitude cost to implement this alternative is estimated to be $81 million; maintenance costs have not yet been quantified.

Alternative 5: Channel Modification, Alternate Materials, from Montague Expressway to UPRR

This alternative would be similar to Alternative 4 above and would also involve the excavation of the inboard toe of the existing levees and construction of a vertical or near-vertical wall with an apron at the resulting channel bench (Figure 5). However, the wall and apron would not be straight planes of concrete, they would be constructed of some alternate material(s), such as interlocking blocks, mechanically stabilized earth (MSE), gabions (gravity wall constructed of stacked wire baskets filled with rocks), or deep-rooting vegetation (biostabilization). These improvements would also be constructed between Montague Expressway and the UPRR bridge and would require selective removal of sediment, a short-height floodwall, and construction of a bypass at Highway 237 (as under Alternative 4). Further analysis would be performed during the next stage of the project to determine the materials and configuration that provide a balance of cost, hydraulic function, appearance, and other project objectives. Initial hydraulic and structural analyses suggest that, to provide the desired water-surface lowering, it is expected that this alternative would also include selective management of vegetation in the channel. Constraints may be due to avoidance of impacts to habitat (primarily ruderal), avoidance of eliminating an escape area for wildlife during storm events, and impacts to wildlife movements. The order-of-magnitude cost to implement this alternative is estimated to be $65 million; maintenance costs have not yet been quantified.

Alternative 6: No Action

District staff has performed a number of maintenance activities along the lower Guadalupe River, including sediment removal, debris removal, and vegetation control, with these activities constrained in the past 10 years because of increasing natural resources regulatory requirements and the increasing concerns over sensitive natural resources areas. Nonetheless, maintenance activities performed in the past will continue to be needed and performed on the lower Guadalupe River. Further LGRP analysis will determine the extent of this work, and the extent to which some or all of this work is appropriately considered part of the No-Action Alternative. Constraints of this alternative include the inability to meet the flood protection objective of the LGRP and the associated flood risks. This alternative could also reduce the potential for environmental enhancement on the lower Guadalupe River.

Alviso Baylands

Each of the action alternatives 1-5, described above, would also include an Alviso Baylands flood control component that is intended to reduce the flooding potential on Alviso Slough near the community of Alviso. The focus of LGRP flood control in Alviso is primarily to address the Guadalupe River contribution to flood conditions in the area. Six components are currently being considered:

• extension of improved levees adjacent to Alviso Slough to its terminus in the Bay;

• extension of Alternative 1 dredging in Alviso Slough to it terminus in the Bay;

• construction of setback levees west of Alviso Slough to the Bay that provides an auxiliary overflow conveyance system;

• construction of an engineered overflow structure from Alviso Slough to flood easements in Cargill Ponds for flood control storage or conveyance (two components considered);

• construction of a phased solution with an engineered overflow to Cargill ponds, flood easements in Cargill Ponds west of Alviso Slough, isolation of Alviso and pond A8D from LGRP design floods and improvements to the New Chicago Marsh source canal flow control mechanisms; and

• tidal restoration of the existing salt ponds adjacent to Alviso Slough by phrasing out salt production, breaching salt pond levees and allowing the tidal processes to re-establish.

Possible Environmental Issues

The resources for which potential adverse effects were identified include river geomorphology, biological resources, water quality, air quality, transportation and traffic, hazardous materials, and cultural resources.

• River Geomorphology. Operation of the LGRP could result in changes in river geomorphology in the subreaches downstream of Interstate 880. Post-project monitoring would focus on channel incision and sediment deposition.

• Biological Resources. Construction of the LGRP could, depending on the alternative, require removal of some shaded riverine aquatic cover and disturbance of the river channel, impacts to wildlife habitat possible effects on escape area for wildlife during storm events, and possible effects on wildlife movements. Such activities could result in adverse effects on fish habitat during and after construction. Anadromous fish evaluated are steelhead, which is listed as threatened under the Endangered Species Act, and chinook salmon.

• Water Quality. Potential construction-related effects on water quality could include temperature changes, turbidity, and possible disturbance and mobilization of mercury present in the sediments.

• Air Quality. Earthmoving associated with constructing Alternative 2 , 3, 4, and 5 could result in increased PM10 (particulate matter less than 10 microns in diameter) emissions.

• Transportation and Traffic. Project construction could result in temporary construction-related traffic congestion.

• Hazardous Materials. Potential construction-related effects on areas surrounding the river could be disturbance and mobilization of mercury and other contaminants present in the area soils and in the groundwater.

• Cultural Resources. Several cultural resource sites exist along the lower Guadalupe River and, depending on the alternative, these sites might be disturbed during LGRP construction. In addition, unknown cultural resources could be discovered and disturbed during construction operations.