For the purpose of Section 14953, a commercial shellfish growing area is threatened if any of the following applies:

1. (a) The State Department of Health Services downgrades the classification applicable to the commercial shellfish growing area.
2. (b) The commercial shellfish growing area is subjected to harvest closure for more than 30 days per calendar year during the previous three years.
3. (c) The State Department of Health Services classifies the commercial shellfish growing area as restricted.
4. (d) The regional board, the Department of Fish and Game, or the California Coastal Commission determines that the commercial shellfish growing area is threatened.