Welcome to Chapter 8, Beaches and Dunes. Statewide Planning Goal 18 defines beaches as gently sloping areas of loose material, such as sand, gravel or cobbles that extend from the low-water line to a definite change in the material type, landform or vegetation line. A dune is "a hill or ridge of sand built up by the wind along sandy coasts." The goal contains a variety of more specific dune definitions, including both active and stabilized dune forms. These definitions may overlap and no one configuration fits all beach and dune areas or systems. These features are the result of dynamic, natural forces of waves and wind, and take many shapes and sizes, changing from day to day, season to season, year to year.
The two principle objectives of Goal 18 are to:
Local jurisdictions are expected to use zoning and policies to meet these objectives.
Local governments must inventory all beach and dune areas. As the inventories of all coastal cities and counties were adopted in the early to mid-1980s, most of these contain only general information. Some jurisdictions have updated inventories with more recent information, particularly in the form of Geographic Information System or GIS maps and data. As beaches and dunes shift over time through erosion or accretion, Oregon Coastal Management Program works closely with the Oregon Department of Geology and Mineral Industries and other agencies to provide updated information to local governments.
Local governments are required to regulate uses and activities on beaches and dunes that may cause erosion, alteration or otherwise create adverse impacts on important scenic, biological and habitat areas. Implementation requirements include limitations on the location of certain types of development and requirements to minimize adverse environmental effects. Requirements also protect development from geologic hazards, wind erosion, ocean undercutting and ocean flooding.
Within the wide variety of dunes on the Oregon coast, Goal 18 identifies these four types:
Active dune forms include foredunes and hummocks with little or no vegetation. An active dune is still moving, growing, or shrinking with the wind and sand. A foredune is the ridge of sand closest to and parallel to the beach while a hummock is a circular elevated mound of sand, usually with vegetation.
Recently stabilized dune forms have sufficient vegetation to begin to stabilize the dune but no significant soil build-up. The dune is too fragile for any structure as loss of vegetation would render it active again. These dune forms include conditionally stable dunes, conditionally stable foredunes, dune complexes and younger stabilized dunes. In the past half-century, European beach grass has become a principal agent for stabilizing dunes on the Oregon coast.
Older stabilized dunes are a third form of dune type. They are stable today, with established vegetation and significant soil development, and are expected to remain so, especially if undisturbed. These dunes often are covered with shore-pine forests and a dense growth of coastal shrubs.
The fourth dune type, interdune forms, are low lying areas between dunes that are scoured by wind and are underwater part of the year due to the high water table during the rainy season. As the wind blows somewhat parallel to the coast during most of the year, it carries away the dry sand to the level of the water table, creating what is called a deflation plain – a wet, low-lying area typically found behind a foredune.
Goal 18 establishes a three-tiered hierarchy for development:
Goal 18 strictly regulates beachfront protective structures and prohibits them if development did not exist before January 1, 1977, the effective date of the Goal. Homes and other development built near the beach prior to that time often are protected from erosion caused by ocean waves. The most common beachfront protective structure is riprap – large rocks placed to absorb the energy from waves. Other protective structures include retaining walls, seawalls and revetments. These so-called hard structures are discouraged because they can create erosion and other problems for adjacent areas, alter sand movement and water currents, reduce public access to the beach and create unpleasant visual and aesthetic impacts.
The Oregon Parks and Recreation Department issues permits for any structures on or adjacent to the beach. In the few cases where new beachfront structures are approved, they must be designed and built to minimize adverse environmental effects.
Sand dunes can build up during certain seasons or climate cycles. Dune grading can alter the dune system and accelerate erosion or create other hazards for adjacent and nearby properties. Goal 18 allows dune grading only in areas committed to development or inside a city’s urban growth boundary when it is conducted as part of an overall plan for managing foredune grading. The Oregon Parks and Recreation Department will not authorize dune grading until such a plan has been completed.
A foredune grading plan must consider the entire beach and area subject to sand build-up or accretion. It must be based on geological information and maintain a specific minimum dune height of four feet above the 100-year flood elevation. This ensures the grading will not lower a dune so much that developed areas behind it are subject to ocean flooding for a 100-year storm event.