SPN-1996-223090 Salinas River Stream Maintenance Program

TO WHOM IT MAY CONCERN: The San Francisco District of the U.S. Army Corps of Engineers (Corps) has received an application to reissue a Department of the Army Regional General Permit (RGP) pursuant to Section 404 of the Clean Water Act (33 U.S.C. §1344) and Section 10 of the Rivers and Harbors Act of 1899 (33 U.S.C. §403). The purpose of this public notice is to solicit comments from the public regarding the work described below:

APPLICANT: Jaime Gonzalez Canon, Resource Conservation District of Monterey County (RCDMC). 744-A La Guardia Street, Salinas, CA 93905

WATERWAY AND LOCATION:  The Salinas River Stream Maintenance Program (SMP) covers 92 linear miles of the Salinas River in Monterey County, from River Mile (RM) 2 near the State Highway 1 bridge, upstream to RM 94 near the town of San Ardo (Figure 1).  The SMP area is divided into 7 River Management Units (RMUs) along the Salinas River mainstem (Figures 2-8) and also includes the lower reaches of three Salinas River tributaries: San Lorenzo Creek in King City, Bryant Canyon Channel in Soledad, and Gonzales Slough between Chualar and Gonzales (Figures 9-11).

EXISTING CONDITIONS: The Salinas River flows approximately 180 miles north/northwest from its headwaters in San Luis Obispo County through the Salinas Valley before reaching Monterey Bay near Castroville, California. The Salinas River watershed is the largest in the central California coast area, with a drainage area of approximately 4,240 square miles. Major tributaries to the Salinas River within the SMP area include Arroyo Seco and San Lorenzo Creek. The SMP area is roughly divided into two reaches based on channel morphology. The lower reach (RM 2.0 – 21.0, which includes RMUs 6 and 7), is generally characterized by a narrower channel (typically about 500 to 1000 feet wide); the upper reach (RM 21.0- 94.0, which includes RMUs 1-5) has a wider channel, with widths that can exceed 2000 feet. The channel bed and banks along both reaches are predominantly sand, with extensive sediment bars that form a complex of braided secondary channels. RMUs along both reaches consist primarily of private agricultural lands that border or extend into the river channel, and also contain bridges, municipal lands and facilities, and other public infrastructure.  Additional details on each RMU are provided in Table 1 of the attached figures.

Historically, floods likely scoured the sediment bars and channel bottom on a regular basis, removing vegetation and transporting sediments.  Since construction of the Nacimiento (1957) and San Antonio (1967) Reservoirs, high flow events have been muted and scouring is less frequent.  Low, non-scouring flows are maintained well into the dry season, extending the growing season for vegetation in the primary low flow channel and along sediment bars. In addition, agricultural encroachment into the Salinas River floodplain has reduced flood flow capacity in some areas which, along with increased vegetation density in the river channel and less sediment mobilization, has increased overall flood risk. 

Non-native invasive plant species including Arundo (Arundo donax) and tamarisk (Tamarix parviflora) have been spreading pervasively in the Salinas River watershed, which has one of the largest infestations of Arundo in the state. Compared to native riparian plants, Arundo forms extremely dense stands but provides little shading of in-stream habitat, leading to increased water temperatures and reduced habitat quality for native wildlife. Once established, Arundo can outcompete and suppress native vegetation, and draws substantially more water from the underlying aquifer than native vegetation. Because of the density of aboveground biomass and equally dense root structure, large stands of Arundo alter the riverine fluvial processes, sediment transport budgets, and geomorphic structure, contributing to increased flood risk. Arundo also increases fire frequency and intensity due to its tall, high fuel load that can burn year round.

To address these issues, a pilot project for stream channel maintenance activities was developed and authorized under an earlier RGP and conducted in RMUs 4 and 5 from 2014 thru 2015.  RGP 20 was then issued in 2016 to authorize expanded maintenance activities in all 7 RMUs and the 3 tributary reaches, and this work has been authorized annually and successfully implemented for the last 10 years.

PROJECT PURPOSE:

Basic: The basic project purpose comprises the fundamental, essential, or irreducible purpose of the project, and is used by the Corps to determine whether the project is water dependent.  The basic project purpose is flood risk reduction along the Salinas River.

Overall: The overall project purpose serves as the basis for the Section 404(b)(1) alternatives analysis and is determined by further defining the basic project purpose in a manner that more specifically describes the applicant's goals for the project while allowing a reasonable range of alternatives to be analyzed.  The overall project purpose is to maintain an efficient permitting process for projects to minimize bank erosion and reduce flood risk to agricultural land adjacent to the Salinas River within the SMP area, while maintaining and enhancing natural habitat and ecological and hydrological processes.

PROPOSED WORK:  The applicant requests reissuance of RGP 20 to allow continued annual authorization of stream channel maintenance work within the RMUs, consisting mostly of vegetation management (mowing and discing), sand/sediment management (channel smoothing), and non-native vegetation removal and herbicide treatment of Arundo and tamarisk (Figure 12). Project activities would create and maintain a series of linear “secondary channels” paralleling the existing low-flow channel (Figure 13) and designed to become active during higher flow events (5-year interval or approximately 25,000 cfs). The objective of the proposed management activities within these RMUs is to mimic natural braiding in the Salinas River. The goal is to increase channel complexity and capacity, slow velocities in the primary low flow channel, and encourage a wider range of riparian habitat conditions (earlier to later successional vegetation communities) that would have been present historically.

Proposed management of secondary channels would be submitted annually for agency review and authorization under RGP 20. Sediment management activities would be conducted between September 1 and November 15 each year, with some vegetation management conducted starting June 1. At the conclusion of each year’s maintenance season, an annual report would be compiled by the RCDMC and submitted to all permitting agencies, with a summary of all maintenance activities and mitigation actions completed for the year.

The proposed locations of secondary channels have been preferentially aligned along meander cutoffs, low-lying undeveloped areas, and former river alignments to mimic the historical braiding of the Salinas River. Most secondary channels would meet, or tie-in with, the existing low flow channel at upstream and downstream locations as would be expected in a more natural braided river channel. Where possible, tie-ins would be located to: (1) avoid or reduce potential impacts to higher value native vegetation (e.g., riparian or wetland areas); (2) in areas where large patches of Arundo are found (i.e., to facilitate non-native species removal); (3) in areas where the bank is already low (e.g., 3-5 feet above the bottom of the low-flow channel, versus 6-7 feet); (4) at existing bends (to facilitate natural overbank flow at the upstream end); and (5) aligned to avoid potential impacts to adjacent banks via increased scour. Downstream tie-in points would also be positively graded at the area joining the low flow channel to avoid potential fish stranding.  In a limited number of cases, the geomorphology or hydrology of the river may require tie-ins be located in an area requiring removal of larger sized riparian vegetation (e.g., multiple mid-successional willows greater than 6 inches dbh).  In those instances, the tie-in would be made through two to four smaller notches ranging from 15-30 feet wide, rather than one larger opening in the riparian corridor that would result in removal of more trees and a larger riparian impact. Pre-construction staking and flagging would also be used to avoid large trees, riparian vegetation, and wetlands, where possible, when creating both secondary channels and their connection to the low-flow channel. Areas where Arundo dominates the tie-in location would be treated to remove all Arundo.

In addition to secondary channels, at limited locations within RMUs 6 and 7 (Figure 14), vegetation maintenance and sediment removal activities would occur in focused selective treatment areas (Figure 15), rather than in linear secondary channels.  The work in these two RMUs would include removing tree limbs and sandbar material in areas directly adjacent to the low flow channel.

Up to 130 potential management areas (secondary channel locations and selective treatment areas) have been identified throughout the 7 RMU’s and 3 tributaries, totaling approximately 875 acres.  The majority of the proposed work within these management areas would be conducted below the Ordinary High Water Mark (OHWM) of the Salinas River or its tributaries.  Maintenance activities in these areas would temporarily impact waters of the U.S. through sediment grading or removal.  Approximately 700 acres of native and non-native vegetation types within the management areas could be disturbed by vegetation management and/or sediment removal under the SMP.  An additional 155 acres of unvegetated or bare ground may be temporarily disturbed during sediment grading or removal.  Up to 554,420 cubic yards (CY) of sediment could be removed annually under the SMP, and no more than 785,000 CY of sediment could be removed in any two consecutive years.  Additionally, no more than 450,000 CY of sediment could be removed from any given 1 mile length of river in the upper reach, and no more than 100,000 CY of sediment could be removed over any 1 mile length of river in the lower reach over a consecutive 2 year period.  These impacts are considered temporary because of the dynamic nature of the river system, which is anticipated to shift vegetation and sediments within the floodplain during moderate to high flow events.  Annual limits on vegetation/grading impacts and sediment removal are summarized below:

SMP Annual Limits of Sediment and Vegetation Removal

AVOIDANCE AND MINIMIZATION: Minimization measures including pre-maintenance surveys, project area staking and avoidance area flagging have been incorporated into the project design.  Impacts to wetland areas would be avoided, and impacts from fill below the ordinary high-water mark (OHWM) of the Salinas River or its tributaries (grading/smoothing and secondary channel tie-ins) are expected to be temporary.  Potential temporary impacts to wetlands would be identified in the annual work plans or annual reports and would generally be addressed by onsite restoration of impacted wetlands. SMP activities are not expected to result in a loss of waters of the U.S.  Most projects to be conducted under this RGP are self-mitigating by improving vegetative communities, removing invasive species, opening up backwater channels, and increasing habitat features for riparian plant and wildlife species.

COMPENSATORY MITIGATION: The SMP mitigation framework is primarily for the requirements of other agencies to address impacts from vegetation removal (e.g. non-fill impacts), which would generally not be subject to USACE jurisdiction.  Impacts to wetland areas would generally be avoided, and impacts from fill below the OHWM of the Salinas River or its tributaries (grading/smoothing and secondary channel tie-ins) are expected to be temporary. This program is not expected to result in a loss of waters of the U.S.  Annual impacts to sensitive habitat and vegetation types in the secondary channels from maintenance activities would be calculated at the RMU-level and would be used to determine annual mitigation needs by type.  Mitigation needs would be identified after avoidance and minimization measures have been implemented during pre-maintenance surveys and would primarily consist of revegetation of disturbed areas.

CULTURAL RESOURCES:  The Corps is evaluating the undertaking for effects to historic properties as required under Section 106 of the National Historic Preservation Act. This public notice serves to inform the public of the proposed undertaking and invites comments including those from local, State, and Federal government Agencies with respect to historic resources. Our final determination relative to historic resource impacts may be subject to additional coordination with the State Historic Preservation Officer, federally recognized tribes and other interested parties.

No resources listed in or eligible for inclusion in the National Register of Historic Places are known to be present in the vicinity of the proposed work; however, the permit area has not been formally surveyed for the presence of cultural resources. Additional work may be necessary to identify and assess any cultural resources that may be present. This notice serves as a request to SHPO, THPO, and/or other interested parties to provide any information they may have regarding historic properties. The Corps would require the applicant to include cultural resources information with annual submission of proposed RGP 20 projects and would assess potential effects on historic properties prior to authorizing any individual projects.

The District Engineer’s final eligibility and effect determination will be based upon coordination with the SHPO and/or THPO, as appropriate and required, and with full consideration given to the proposed undertaking’s potential direct and indirect effects on historic properties within the Corps-identified permit area.

ENDANGERED SPECIES: The Corps has performed an initial review of the application, the U.S. Fish and Wildlife Service (USFWS) Information for Planning and Consultation (IPaC), National Marine Fisheries Service (NMFS) West Coast Region Section 7 Mapper, and the NMFS Critical Habitat Mapper to determine if any threatened, endangered, proposed, or candidate species, as well as any proposed or final designated critical habitat may occur within the boundary of the proposed project. Based on this initial review, the Corps has made a preliminary determination that the proposed project may affect species and critical habitat listed in the table below. No other ESA-listed species or critical habitat will be affected by the proposed action.

ESA-listed species and/or critical habitat potentially present in the action area.

Pursuant to Section 7 ESA, any required consultation with the Service(s) will be conducted in accordance with 50 CFR part 402. The Corps is the lead Federal agency for ESA consultation for the proposed action. Any required consultation will be completed by the Corps.

This notice serves as request to the U.S. Fish and Wildlife Service and National Marine Fisheries Service for any additional information on whether any listed or proposed to be listed endangered or threatened species or critical habitat may be present in the area which would be affected by the proposed activity.

ESSENTIAL FISH HABITAT: Pursuant to the Magnuson-Stevens Fishery Conservation and Management Act 1996, the Corps reviewed the project area, examined information provided by the applicant, and consulted available species information.

The Corps intends to initiate Essential Fish Habitat (EFH) consultation separately from this public notice. A separate EFH consultation package will be sent to the National Marine Fisheries Service (NMFS). The Corps will not make a permit decision until the consultation process is complete.

NAVIGATION: The proposed structure or activity is not located in the vicinity of a federal navigation channel.

SECTION 408: The applicant will not require permission under Section 14 of the Rivers and Harbors Act (33 USC 408) because the activity, in whole or in part, would not alter, occupy, or use a Corps Civil Works project.

WATER QUALITY CERTIFICATION: The Central Coast Regional Water Quality Board (RWQCB) issued a for the Salinas River SMP on August 31, 2016, which was valid for a ten year period through November 30, 2025. On May 19, 2026, the RWQCB issued an amendment which extended the water quality certification an additional 10 years through November 30, 2035.

NOTE:  This public notice is being issued based on information furnished by the applicant. This information has not been verified or evaluated to ensure compliance with laws and regulation governing the regulatory program. The geographic extent of aquatic resources within the proposed project area that either are, or are presumed to be, within the Corps jurisdiction has been verified by Corps personnel.

EVALUATION: The decision whether to issue a permit will be based on an evaluation of the probable impact including cumulative impacts of the proposed activity on the public interest. That decision will reflect the national concern for both protection and utilization of important resources. The benefits, which reasonably may be expected to accrue from the proposal, must be balanced against its reasonably foreseeable detriments. All factors which may be relevant to the proposal will be considered including cumulative impacts thereof; among these are conservation, economics, esthetics, general environmental concerns, wetlands, historical properties, fish and wildlife values, flood hazards, floodplain values, land use, navigation, shoreline erosion and accretion, recreation, water supply and conservation, water quality, energy needs, safety, food, and fiber production, mineral needs, considerations of property ownership, and in general, the needs and welfare of the people. Evaluation of the impact of the activity on the public interest will also include application of the guidelines promulgated by the Administrator, EPA, under authority of Section 404(b) of the Clean Water Act or the criteria established under authority of Section 102(a) of the Marine Protection Research and Sanctuaries Act of 1972.  A permit will be granted unless its issuance is found to be contrary to the public interest.

COMMENTS: The Corps is soliciting comments from the public; Federal, State, and local agencies and officials; Indian Tribes; and other Interested parties in order to consider and evaluate the impacts of this proposed activity. Any comments received will be considered by the Corps to determine whether to issue, modify, condition, or deny a permit for this proposal. To make this determination, comments are used to assess impacts to endangered species, historic properties, water quality, general environmental effects, and the other public interest factors listed above. Comments are used in the preparation of an Environmental Assessment (EA) and/or an Environmental Impact Statement pursuant to the National Environmental Policy Act (NEPA). Comments are also used to determine the need for a public hearing and to determine the overall public interest of the proposed activity.

The San Francisco District will receive written comments on the proposed work, as outlined above, until August 28, 2026. Comments should be submitted electronically via the Regulatory Request System (RRS) at https://rrs.usace.army.mil/rrs or to Greg Brown, at gregory.g.brown@usace.army.mil. Alternatively, you may submit comments in writing to the Commander, U.S. Army Corps of Engineers, San Francisco District, Attention:  Greg Brown, 450 Golden Gate Ave., San Francisco, CA 94102. Please refer to the permit application number in your comments.

Any person may request, in writing, within the comment period specified in this notice, that a public hearing be held to consider the application. Requests for public hearings shall state, with particularity, the reasons for holding a public hearing. Requests for a public hearing will be granted, unless the District Engineer determines that the issues raised are insubstantial or there is otherwise no valid interest to be served by a hearing.