| Abstract | For Oregon, as for most coastal states, the sea represents both a valuable resource and a
potential threat. The sea provides many Oregonians with a livelihood, food, and
recreation, and it attracts visitors to our coastal communities. The sea also represents a
significant threat in the form of an inevitable earthquake-generated tsunami, akin to the
recent one in Indonesia. Understanding the nature of Oregon’s Territorial Sea is critical to
sustaining sport and commercial fisheries, coastal tourism, wave power, and a broad
range of other ocean derived ecosystem services valued by Oregonians, in addition to
addressing the threat posed by a major tsunami. Presently, we have detailed bottom
mapping of only about 5% of the area of the Oregon Territorial Sea, which extends 3
nautical miles from the coast and comprises approximately 950 square nautical miles.
Effective decisions concerning the management and conservation of ocean resources in
accordance with Department of State Lands Strategic and Asset Management Plans
depend upon better knowledge of nearshore waters. To address this problem the Oregon
Department of State Lands proposes to initiate a seafloor mapping program within
Oregon’s Territorial Sea. This in part comes from recognition by the State, and by other
States, that no Federal entity is charged with or has intentions to map State waters in the
United States.
Given the renewed and diverse interests in activities within Oregon’s Territorial Sea
(outlined above) the Multibeam Mapping Project advances the agencies mission and
responsibility to manage state owned lands, offshore lands and coastal estuarine
tidelands, as well as submerged and submersible lands of the navigable waterways within
the state. A comprehensive mapping of these state lands provides the fundamental unit
(map) from which all aspects of management are developed. Goals 1 and 2 of the 2006-
2010 Strategic Plan are directly supported through this program by providing a product
that enables waters of the state to be spatially managed for the greatest benefits in
conservation, restoration, and protection. More generally, this program supports the
Asset Management Plan (AMP) by enabling a valuation of core real estate assets in the
territorial sea. This valuation of Territorial Sea assets can be used with the policy
direction and management principles set forth in the AMP to guide both short and longterm
management of Common School Fund lands for greatest benefit. Overall, this
project begins a transition toward informed science-based or information-based
management of the nearshore environment.
The State of Oregon has jurisdiction and management responsibilities for the seafloor out
to 3 miles from the nearest point of land. To date however, no map of the Territorial
Seafloor has been made. High resolution mapping of the Oregon Territorial Seafloor is
designed to address multiple issues. Numerous activities in the nearshore waters of
Oregon, existing and proposed, impact the nearshore environment, and fall within the
management authority of the Department of State Lands. At our present level of
knowledge, we do not have the capacity to assess projects such as marine reserves, wave
energy and other future activities without basic information on the depth, seafloor
geology and biology.
Seafloor mapping provides the information needed. For wave energy, surface and
subsurface information is needed to properly site anchors, to model currents, and to
assess the local environmental impacts within a geobiological context for proposed sites.
For marine reserves or any conservation activity, seafloor mapping provides the basis for
mapping of biological habitats, their diversity, and their distribution along the Oregon
coast. This basic information presently does not exist, and is an integral part of the
proposed project. With respect to Geohazards, seafloor mapping addresses both the
tsunami hazard issue and coastal erosion by providing accurate modern bathymetry that is
used directly to model tsunami and storm waves and predict their impacts. Presently,
without such data, this type of modeling is not possible to the accuracy needed for the
future.
The mapping program underway and discussed in this report is the outgrowth of a
Seafloor Mapping Task Force formed at Oregon State University in 2006. This group
met on numerous occasions through 2007 and 2008 to discuss the needs for nearshore
mapping with state legislators, biologists, geologists and members of coastal
communities to develop the proposal. Presentations were made to the Joint Committee
on Emergency Preparedness and Ocean Policy on four occasions, and to the State Land
Board. Further discussions were held with the Department of Land Conservation and
Development, DOGAMI, ODFW and others about the needs and application to the
missions of these agencies. Discussion and questions about tsunami modeling, wave
energy siting, and marine reserves and the needs for basic seafloor data were addressed at
these meetings. Subsequently, this topic was discussed extensively at OPAC meetings,
meetings of the Marine Reserves Working Group (MRWG), and the Science and
Technology Advisory Committee (STAC), charged with advising the OPAC on Marine
Reserves and other ocean management issues. There has been unanimous support for the
seafloor mapping project, with no negative opinions or impacts. Members of the public
and in particular the fishing communities were present at many of these meetings, and
expressed the strong sentiment that little could be achieved in management of the coastal
ocean without the basic seafloor data that are now being collected under this project.
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