Clatsop County beaches from Seaside to the Columbia River will be closed to razor clamming beginning Monday.

The 18 miles of beach north of Tillamook Head close to razor clam harvest annually from mid-July until Sept. 30 to give young clams a chance to establish themselves during the summer. The state completes stock assessments during this period.

Last year, they found that clams were too small and extended the annual closure until spring to give clams time to grow.

The Clatsop beaches are the most productive razor clam beds in the state, accounting for more than 90 percent of the total harvest.