Clatsop County's Coastal Erosion Hazard Annex adequately describes the causes and characteristics of coastal erosion hazards. Cannon Beach is a city of roughly 4 miles in length and 1/2 mile in width. All four miles are bordered on the west by the Pacific Ocean. While there has been relatively little significant erosion in the past two or three decades, the threat is always present, especially during the winter months when Pacific storms bring huge surf, heavy rain, and strong winds to the region.
There are five primary areas of concern to Cannon Beach regarding coastal erosion. These are: 1) Silver Point at the south end of Cannon Beach; 2) the "S-Curves" area in the middle of Cannon Beach; 3) the Ecola Creek mouth just in front of the City's largest commercial area; 4) Ecola State Park; and 5) The Cove Beach / Falcon Cove area, approximately six miles south of Cannon Beach. Although Cove Beach is not within City limits, Cove Beach's residents are a part of Cannon Beach's social fabric. Likewise, Ecola State Park is not in the City Limits but it is adjacent to the City's northern boundary and one of the major tourist attractions to the City of Cannon Beach. All five of these areas are further described below:
- Silver Point - this area includes the southern portion of the City and the area immediately adjacent to the City. A large landslide in the early 1970s took out two residential structures and a large portion of Highway 101, interrupting commerce on the north Oregon coast for months. The slide was due to a combination of coastal erosion and poor drainage in the sub soils.
- S-Curves - this area is at risk due to a combination of poor drainage and coastal erosion. The City continues maintain this area as needed.
- Drainage mitigation measures and monitors the ground motion. Most of the recent problems have been associated with exceptionally wet winters. Sliding in this area has the potential to damage water and sewer services to the Tolovana Park area of Cannon Beach, disrupt the major north-south City street, and compromise public safety operations.
- Ecola Creek - the point where Ecola Creek meets the Pacific Ocean is subject to coastal erosion due to the combination of incoming wave action and outgoing creek drainage. The resultant turbulence has undermined seawalls and eroded large amounts of fore dune on various occasions during the past three decades.
- Ecola State Park - while not part of the City Limits, this park has had a history of active slides caused by coastal erosion. In the 1960s, most of what is now the main park area slid into the ocean. Within the past 5 years, the trail to Crescent Beach, the southern part of the State Park, slid away due to erosion and has not been repaired. This park is a major draw for the tourists who visit Cannon Beach and without it, the City's economy would suffer greatly. The City is at this time, unaware of any mitigation efforts that could be made to harden the park against such erosion.
A mixture of fore-dunes and manmade structures protects much of the City's frontage on the Pacific Ocean. Significant storms or rising ocean levels may reduce or remove these structures, suddenly or gradually. Additionally, the entire municipal oceanfront is at high risk for coastal erosion due to its proximity to the ocean.
Clatsop County describes coastal erosion as a 'chronic' hazard along the Oregon Coast, especially on sand spits, bluffed coastline, and dune-backed beaches. Damages caused by chronic hazards are usually gradual and cumulative. As such, the County estimates a 'high' probability that coastal erosion will continue to occur along the County's coastline. The same is true for the City of Cannon Beach.
Likewise the County estimates a 'high' vulnerability to coastal erosion, meaning more than 10% of the population or regional assets are likely to be affected by this hazard. Due to the City's large amount of development along its coastline, Cannon Beach estimates the same level of vulnerability.