Well water a top concern for produce growers after recent flooding

Wisconsin State Farmer
Produce can be contaminated directly or indirectly by flood water that almost certainly contains bacteria, chemicals or both.

MADISON – With weekend farmers markets in full swing, produce consumers and growers alike should be aware of safety concerns related to wells and fields flooded during recent severe weather, according to the Wisconsin Department of Agriculture, Trade and Consumer Protection.

Produce can be contaminated directly or indirectly by flood water that almost certainly contains bacteria, chemicals or both. 

“When flooding occurs like it has the past few days, two things generally happen that might have negative impacts on produce. First is contamination of well water used to wash produce and second is direct contamination of produce in the field,” said Shawn Bartholomew, Safe Wisconsin Produce program manager for the Division of Food and Recreational Safety. 

Generally speaking, state and federal food safety regulations do not directly address flooding. Regulations governing application of manure and pesticides also do not address flooding. The only absolute is that produce that has come in contact with flood water is considered unfit for human or animal consumption. 

Producers who use well water to wash produce prior to sale should pay close attention to the condition of their well. Contamination should be suspected if the flood waters can enter the top of a well or migrate underground to a well from a neighbor’s flooded well, according to the Department of Natural Resources website.  

Wells located in pits, basements and low-lying areas are especially susceptible, and may not show obvious signs of contamination. Well owners who observe flooding or changes in their water should assume their wells are contaminated and should stop using the water.

“If anyone is growing and selling produce to the public, and normally uses well water to prepare it, they should switch to a known safe source and have the well disinfected before they start using it again,” Bartholomew says.

To be sure well water is safe to use again, have it tested. A list of certified water laboratories is available from the DNR website at dnr.wi.gov. The laboratory will provide a water sampling kit. 

Fruits and vegetables can also be directly contaminated by flood water in the field.  “A good rule of thumb is that if flood water has touched it, it shouldn’t be sold or consumed,” Bartholomew says.

Research on flooded produce done in New York and Virginia suggests that a 30-foot limited-harvest buffer zone from the edge of a flood is advisable to minimize contamination risk carried by splashing water or wind.  

It is recommended that no produce with edible portions exposed during the flood be harvested within the buffer zone and that growers should wait 60 days before replanting the flooded and buffer areas. Crops located in the buffer area on which the edible part of the plant could not come in contact with flood water should be evaluated case by case. 

“If the edible portion develops after flood waters recede, it’s not automatically considered unfit for consumption.  It is the producer’s decision whether to sell the produce,” Bartholomew says. 

Produce with a protected fruit or impervious outer skin, like a watermelon or cantaloupe, may be contaminated on the surface but not on the inner edible portion.  However, outer contamination can still be a major concern, especially with melons because pathogens on the surface are moved to the edible part as the product is sliced and eaten raw.