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Under the Corps' Regulatory Program, a public notice is the primary method for advising all interested parties of a proposed activity for which a permit is sought. Soliciting comments and information necessary to evaluate the probable impacts on the public interest. Public notices are also published to inform the public about new or proposed regulations, policies, guidance or permit procedures.

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SPK-2023-00258, Public Notice of Proposed Hamilton Bend Mitigation Bank Mitigation Bank, Colusa County, California.

Published July 8, 2024
Expiration date: 8/7/2024

Comment Period: July 5, 2024 – August 4, 2024

SUBJECT: The U.S. Army Corps of Engineers, Sacramento District, (Corps) is evaluating a proposal to establish the Hamilton Bend Mitigation Bank (Bank), which would result in the re-establishment of approximately 125 acres and enhancement of approximately 20 acres of waters of the United States, including wetlands, in or adjacent to the Sacramento-Stone Corral watershed, This notice is to inform interested parties of the proposed activity and to solicit comments. A copy of the Hamilton Bend Mitigation Bank prospectus is available online at the following location,278:P278_BANK_ID:6600.

AUTHORITY: This prospectus is being evaluated under 33 Code of Federal Regulations (CFR) Part 332.8.

SPONSOR:         Westervelt Ecological Services

                              3636 American River Drive, Suite 120

                              Sacramento, California 95864

                              Contact: Ms. Dayna Winchell


LOCATION: The approximately 180-acre site is located on the east bank of the Sacramento River at River Mile 151, approximately 3.5 miles north of the City of Colusa Latitude 39.272836°, Longitude -122.015997°, in Colusa County, California.

PROJECT DESCRIPTION: The prospective Sponsor proposes to establish an approximately 180-acre mitigation bank. The project would result in the re-establishment of approximately 125 acres and enhancement of approximately 20 acres of waters of the United States, including wetlands, in or adjacent to the Sacramento-Stone Corral watershed. The Bank proposes to offer approximately 116 riverine riparian credits, 9 floodplain riparian re-establishment credits and approximately 20 riverine and floodplain riparian enhancement credits. All credits are proposed at a 1:1 ratio per acre.

The Service Area includes: The Sacramento River 10-digit hydrologic unit code (HUC) where the bank property is located (HUC 180201412), and the adjacent 10-digit HUCs along the main stem of the Sacramento River where there are active stream channels and floodplain riparian environments and linear riparian habitats. The service area was further refined to the upper limits of similar ecological features on the USEPA Levell III Ecoregion map, meaning that portions of the 10-digit HUCs not in similar ecoregions to the Bank property were excluded. The service area does not go beyond the upstream and downstream limits of the Lower Sacramento River 6-digit HUC boundary. The attached drawings provide additional details.


Environmental Setting. There are approximately 20 acres of riverine and floodplain riparian wetlands within the Bank site. The Bank site is located on a bend in the Sacramento River that is known as Hamilton Bend and is located between the Moulton Weir and Colusa Weir. Most of the natural hydrology on-site has been altered through farming practices, levees, and weirs. The site is characterized by agricultural production consisting primarily of walnut orchard and some areas of winter wheat. Infrastructure on the site is limited to irrigation that is associated with the walnut orchard, including an agricultural well that is located in the middle of the Bank site. Because the site is currently used for agricultural purposes, it is mostly level with the exception of the berms along the edges, which protect the Bank site from regular flooding, and a historic channel alignment low spot that supports riparian forest. The existing wetlands are located in the riparian habitat along the perimeter of the site along a thin band of the river’s edge and an existing area of low elevation.

Surface water within the Sacramento Stone-Corral watershed includes various streams and creeks, with the Sacramento River being the largest water source. Sacramento River flow at the Bank site is highly regulated by Shasta Dam Releases, and many irrigation diversions and flood control projects. Moulton Weir is located upstream of the project site downstream of Butte City and can divert a maximum of 40,000 cubic feet per seconds (cfs) to the Butte sink and Sutter Bypass during flood conditions. The Colusa Weir is located 3.5 miles downstream from Hamilton Bend, and 2.5 miles upstream of the City of Colusa and USGS gaging station 11389500. The Colusa weir can divert a maximum flow of 60,000 cfs to the Sutter Bypass during flood conditions. While most of the site is at elevations below the 2-year peak flood flow elevation, the orchards are currently protected from seasonal flooding with a farm berm on the eastern boundary, natural river deposits on the southern edge of the orchard, and a training berm on the western boundary. The farm berm and natural river deposit elevations are just above 2-year peak flood inundation elevation, with the western training berm being significantly higher in elevation. The orchard portion of the site currently only receives water through natural precipitation or irrigation, only flooding during flows higher than the 2-year designed storm. A portion of the Bank site on the southeast is not farmed or bermed and currently experiences annual flooding.

The Bank site contains four mapped soil types: Moonbend silt loam, Vina loam, Tujunga loam, and Riverwash. All the mapped soils are associated with channels and floodplains of the Sacramento River and are included on the National Hydric Soil List, making them suitable for the restoration activities at the Bank.

A Department of the Army permit may be required for restoration activities.

OTHER GOVERNMENTAL AUTHORIZATIONS: The Interagency Review Team responsible for the review and approval of the proposed mitigation bank includes representatives from the Corps, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, National Marine Fisheries Service, California Department of Fish and Wildlife, and the Central Valley Regional Water Quality Control Board.

HISTORIC PROPERTIES: Based on the available information (including Sponsor's preliminary report entitled Hamilton Bend Property Cultural Resources Study Report), no cultural resources were identified within the project's area of potential effect.

ENDANGERED SPECIES: The proposed Bank may affect federally listed endangered or threatened species or their critical habitat. The Corps will initiate consultation with the U.S. Fish and Wildlife Service and/or the National Marine Fisheries Service, pursuant to Section 7 of the Endangered Species Act, as appropriate.

ESSENTIAL FISH HABITAT: The proposed Bank will not adversely affect Essential Fish Habitat (EFH) as defined in the Magnuson-Stevens Fishery Conservation and Management Act.

The above determinations are based on information provided by the Sponsor and our preliminary review.

EVALUATION FACTORS: 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 Bank. Any comments received will be considered by the Corps to assess impacts on endangered species, historic properties, water quality, general environmental effects, and other public interest factors. Comments are used in the evaluation of the proposed Bank per 33 CFR Part 332.8 and in the preparation of an Environmental Assessment pursuant to the National Environmental Policy Act.

SUBMITTING COMMENTS: Written comments, referencing Public Notice
SPK-2023-00258 must be submitted via email to the office listed below on or before August 4, 2024.

Ms. Denielle Wise
Project Manager
US Army Corps of Engineers, Sacramento District
Telephone: (916) 557-7186

Attachments: 4 drawings

Figure 1: Regional Vicinity Map

Figure 2: Bank Location Map

Figure 3: Conceptual Design

Figure 4: Service Area Map