Yaquina Bay, Oregon Ocean Dredged Material Disposal Sites Evaluations Study and Environmental Assessment


Title: Yaquina Bay, Oregon Ocean Dredged Material Disposal Sites Evaluations Study and Environmental Assessment
Publication Date:
February 01, 2012
Pages: 47

Document Access

Attachment: Access File
(580 KB)


US Army Corps of Engineers; US Environmental Protection Agency (2012). Yaquina Bay, Oregon Ocean Dredged Material Disposal Sites Evaluations Study and Environmental Assessment. Report by US Army Corps of Engineers and US Environmental Protection Agency (EPA). pp 47.

This Ocean Dredged Material Disposal Site (ODMDS) Evaluation and Environmental Assessment has been jointly prepared by the U.S. Army Corps of Engineers (USACE) and U.S. Environmental Protection Agency (EPA). The purpose of this evaluation is to provide documentation in support of final designation by EPA of two ODMDSs needed for long-term use by the authorized Yaquina Bay navigation projects. This evaluation will determine if the proposed North and South ODMDS offshore of Yaquina Bay, Oregon, fully meets all criteria and factors set forth in Parts 228.5 and 228.6 of Title 40 Code of Federal Regulations (CFR). These regulations were promulgated in accordance with the criteria set out in Sections 102 and 103 of the Marine Protection, Research and Sanctuaries Act of 1972. Further, this document is intended to provide sufficient information to determine compliance with the National Environmental Policy Act, the national Historic Preservation Act, the Coastal Zone Management Act, and Endangered Species Act. Use of the sites would be for disposal of material dredged for operation and maintenance of the federally authorized navigation project at Yaquina Bay, as well as through separate Section 103 permit evaluation for disposal of dredged material from other dredging projects.


The availability of ODMDSs in the vicinity of Yaquina Bay are necessary to maintain safe deep-draft navigation through authorized federal channels and permitted actions. The historic Interim and nearshore Section 103 site experienced mounding, generating a potentially hazardous navigation safety condition, and had limited site capacity to receive future dredge material disposals. Commercial shippers, crab fishermen, and the U.S. Coast Guard expressed concern over this situation to both the USACE and EPA. While the situation may not have constituted an imminent hazard to life and property, which would warrant an emergency, the EPA and USACE agreed that prudent management action was required in order to prevent any further adverse conditions from developing. Efforts were undertaken by the federal government to temporarily expand the historic Interim and nearshore Section 103 sites in 1998 and to manage distribution of the maintenance dredged material within the available site while seeking a more permanent management solution. The need for ocean dumping and implementation of a management solution by USACE and EPA were at a point where the ability to maintain the Yaquina Bay project was at risk. Unless the Yaquina Bay project can be maintained, continued commercial use of the existing navigation channels at their authorized depth would not be possible.


The rough seas encountered at the Yaquina Bay entrance preclude the safe and efficient operation of any dredge other than a hopper dredge. Upland disposal of dredged material from a hopper dredge operation is not economic due to the need to double handle the material and sufficient upland capacity is unavailable. Disposal of the material dredged from Yaquina Bay, therefore, must occur at an in-water site.


While it is possible to dredge and transport material back into the estuary for disposal, there is a lack of suitable estuarine and upland disposal sites. Further, estuarine habitats are unique and far less extensive than are sandy nearshore oceanic habitats. Estuarine disposal would cause greater adverse environmental impacts than would ocean disposal.


Table B-1 in Appendix B provides dredged material volumes estimated for the Yaquina Bay federal navigation project from 1928-2010. Future estimated total disposal quiantity for the long-term maintenance dredging of the navigation channel is expected to remain relatively constant.


Though the volume is expected to be minor compared to the federal dredging volumes, the designated sites may receive material dredged by non-USACE entities and disposed under specific permits issued by USACE. With the fundamental need for ocean dumping having been demonstrated, USACE and EPA had to consider the needed disposal capacity which influences the number and/or size of site(s). The USACE conducts their site capacity modeling based on a 20-year outlook (Appendix B).


Given their modeling results, two ocean disposal sites, the North ODMDS and South ODMDS are proposed (Figure 1). Due to their size, disposal capacity was considered sufficient for approximately 20 years or more for each. These proposed sites replace the nearshore Section 103 Site in the government's preferred action for management of dredged material at Yaquina Bay. The need for designation of these sites pursuant to 40 CFR 227 Subpart C is considered demonstrated.

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