Dear Gretchen:

Thanks for contacting the UVM Extension Master Gardener Helpline with your question about the potato crop that has been inundated by flood water. We're sorry if the flooding has affected your gardens.  

You are correct that the potatoes from a garden that was inundated with flood water should not be harvested and eaten because they are considered "adulterated."  You should discard them or till them into the soil to a depth of at least 6 inches. Then add compost to the garden to increase tilth and dilute any contaminants. Finally, plant cover crops to speed the decline of pathogens before planting vegetables in that garden the next season.

We attach links to two resources that provide greater detail: 

https://www.uvm.edu/sites/default/files/Extension-Community-Horticulture/Resources/After_the_Flood_Tips_on_Edible_Garden_Plants.pdf
https://www.uvm.edu/sites/default/files/Extension-Community-Horticulture/Resources/Flood-Recovery_Guidance_for_Lawns_and_Gardens.pdf

Be sure to take good care of yourself during this difficult time.

Regards,

Pat