(a) The director may authorize any work for any purpose authorized by Section 4675 as an exercise of the director’s emergency powers and may request the assistance of any federal agency or person in connection with that work if any of the following conditions exist:

1. (1) Natural vegetative cover has been denuded to the extent that precipitation may create floods and serious soil depletion and erosion.
2. (2) The denuded area is of a size, and the topography and soil characteristics of such a nature, that soil loss and floods will have a significant effect upon watershed values and the public health, safety, or welfare.
3. (3) Vegetative cover will not be restored by natural means in time to effectively prevent undue erosion and flood runoff.
4. (4) Woody plants and debris within or adjacent to the watercourse channels in or directly downstream from the denuded areas will significantly impede flood runoff or accelerate channel scour. Prior to commencing any work in response to this condition, the director shall advise the Director of Fish and Game of the proposed work.