Comment Period: April 20, 2021–May 5, 2021
SUBJECT: The U.S. Army Corps of Engineers, Sacramento District, (Corps) is evaluating a permit application for the discharge dredged or fill material in approximately 2.4 acres of waters of the United States to construct the Upper Mormon Slough Erosion and Flood Control project. This notice is to inform interested parties of the proposed activity and to solicit comments.
AUTHORITY: This application is being evaluated under Section 404 of the Clean Water Act for the discharge of dredged or fill material in waters of the United States.
APPLICANT: San Joaquin County Public Works, Attn: Mr. Glenn Prasad, 1810 E Hazelton Avenue, Stockton, CA, 95205-6232.
LOCATION: The approximately 20.20-acre project site is located on Mormon Slough, near the intersection of Highway 26 and Escalon Bellota Road, Latitude 38.04795°, Longitude -121.01662°, San Joaquin County, California, and can be seen on the Linden USGS Topographic Quadrangle.
PROJECT DESCRIPTION: The proposed project consists of repairs to approximately 4,728 linear feet of the north and south banks of the upper segment of Mormon Slough near the Escalon-Bellota Bridge in San Joaquin County, California. Based on the information provided by the applicant, the project would result in impacts to approximately 2.40 acres of open waters.
A portion of the Calaveras River flow is directed into Mormon Slough at the Bellota Diversion Facility. Mormon Slough flows in a southwesterly direction for several miles before merging into the Stockton Diverting Canal, which returns the flow to the Calaveras River. Project activities include excavating to remove compromised material in the channel, and then repairing the channel slope with a variety of materials including soil-filled rock slope protection (RSP), a coarse filter bed, earth fill, and launch rock.
Currently, the channel is eroding toward State Route 26 on its northern bank and toward neighboring structures and orchards on its southern bank. Field observations show that erosion and undermining of the existing slopes is leading to incremental collapse and/or oversteepening of the slopes, which is considered the most prevalent mode of failure of the system to be addressed by the repair design.
The repairs would consist primarily of installing RSP, which generally consists of riprap of varying size, soil, gravel, and a textile fabric above the ordinary high-water mark to prevent downward migration of the soil. To promote growth of vegetation, the RSP voids would be filled with agricultural soil and seeded with grasses (i.e., soil filled RSP). Excavation prior to placement of RSP would generally be limited to removal of loose surface debris from past slope failures, minor grading to produce relatively smooth surfaces to prepare for RSP, or to key the repairs into the existing slopes. After grading, workers would install a coarse sand or gravel filter bed that will seal cracks or openings in the base soil. A base of launch rock would be installed at the lower edge of the filter, and RSP would be laid over the filter bed.
Proposed construction would occur during the summer months, sometime between mid-June and mid-September depending on final design completion and permitting status. Based on the available information, the overall project purpose is to repair the existing Mormon Slough flood control system by stabilizing the eroding banks. The applicant believes there is a need to perform erosion and flood system repair to the banks of Mormon Slough. The attached drawings provide additional project details.
Environmental Setting. There are approximately 4.90 acres of perennial stream and 0.06 acre of riparian wetlands within the project area. The site is characterized by upper Mormon Slough and associated levees, adjacent orchards, and ruderal vegetation near the slough. Topography varies from relatively level ground on both sides of the slough to the steep slopes of the banks of the slough. The upper banks support mixed riparian woodland vegetation composed of trees and shrubs as well as non-native annual grasses and forbs.
Alternatives. The applicant has not provided information concerning project alternatives. Additional information concerning project alternatives may be available from the applicant or their agent. Other alternatives may develop during the review process for this permit application. All reasonable project alternatives, in particular those which may be less damaging to the aquatic environment, will be considered.
Mitigation. The Corps requires that applicants consider and use all reasonable and practical measures to avoid and minimize impacts to aquatic resources. If the applicant is unable to avoid or minimize all impacts, the Corps may require compensatory mitigation. The applicant has proposed to purchase compensatory mitigation credits.
OTHER GOVERNMENTAL AUTHORIZATIONS: Water quality certification or a waiver, as required under Section 401 of the Clean Water Act from the Central Valley Regional Water Quality Control Board is required for this project. The applicant has indicated they have applied for certification.
HISTORIC PROPERTIES: Based on the available information (including applicant's report titled Phase 1 Cultural Resource Inventory Report for the Mormon Slough Bank Stabilization Project, San Joaquin County, California, dated April 2020), two cultural properties were identified within the project’s area of potential effects. The Corps will initiate consultation with the State Historic Preservation Officer under Section 106 of the National Historic Preservation Act, as appropriate.
ENDANGERED SPECIES: The proposed activity 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 the National Marine Fisheries Service, pursuant to Section 7 of the Endangered Species Act, as appropriate.
ESSENTIAL FISH HABITAT: The proposed project may adversely affect Essential Fish Habitat. The Corps will initiate consultation with the National Marine Fisheries Service, pursuant to Magnuson-Stevens Fishery Conservation and Management Act, as appropriate.
The above determinations are based on information provided by the applicant and our preliminary review.
EVALUATION FACTORS: The decision whether to issue a permit will be based on an evaluation of the probable impacts, including cumulative impacts, of the described activity on the public interest. That decision will reflect the national concern for both protection and utilization of important resources. The benefit, which reasonably may be expected to accrue from the described activity, must be balanced against its reasonably foreseeable detriments. All factors which may be relevant to the described activity will be considered, including the cumulative effects thereof; among those are conservation, economics, aesthetics, general environmental concerns, wetlands, historic 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, consideration of property ownership and, in general, the needs and welfare of the people. The activity's impact on the public interest will include application of the Section 404(b)(1) guidelines promulgated by the Administrator, Environmental Protection Agency (40 CFR Part 230).
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 decision, comments are used to assess impacts on endangered species, historic properties, water quality, general environmental effects, and other public interest factors listed above. Comments are used in the preparation of an Environmental Assessment and/or an Environmental Impact Statement pursuant to the National Environmental Policy Act. Comments are also used to determine the need for a public hearing and to determine the overall public interest of the proposed activity.
SUBMITTING COMMENTS: Written comments, referencing Public Notice SPK-2017-00529 must be submitted to the office listed below on or before May 5, 2021.
Marc Fugler, Project Manager
U.S. Army Corps of Engineers, Sacramento District
Regulatory Division, Special Projects Branch
The Corps is particularly interested in receiving comments related to the proposal's probable impacts on the affected aquatic environment and the secondary and cumulative effects. Anyone may request, in writing, that a public hearing be held to consider this application. Requests shall specifically state, with particularity, the reason(s) for holding a public hearing. If the Corps determines that the information received in response to this notice is inadequate for thorough evaluation, a public hearing may be warranted. If a public hearing is warranted, interested parties will be notified of the time, date, and location. Please note that all comment letters received are subject to release to the public through the Freedom of Information Act. If you have questions or need additional information please contact the applicant or the Corps' project manager Marc Fugler, (916) 557-5255, Marc.A.Fugler@usace.army.mil.
Attachments: 9 drawings