Questions abound about implementation of the Food Safety Modernization Act. To keep you abreast of the latest information, Good Fruit Grower, in cooperation with industry professionals, is presenting an occasional column to answer some of the more frequently asked questions.

What water sampling will FSMA require me to do next year?

The current regulatory language of the FSMA Produce Safety Rule requires growers to follow a specific process of taking a series of water samples on each water source to establish a Microbial Water Quality Profile (MWQP) that is updated with new samples each year.

However, the Food and Drug Administration announced in March 2017 that the agency is reconsidering the entire water quality section of the rule, including sampling standards and methodologies, due to concerns raised by the industry regarding its complexity and difficulty to implement on the farm.

Industry associations like the Northwest Horticultural Council (NHC) and Washington Tree Fruit Research Commission (WTFRC) will be weighing in with FDA as this process moves forward.

In the interim, growers should consider holding off on making new investments in meeting the specific water requirements of the Produce Safety Rule until this process is complete.

However, it is expected that water sampling in some form will still be required, so training on good water sampling techniques including training courses offered by the Washington State Tree Fruit Association (WSTFA) continues to be valuable.

Please remember that the nonwater provisions of the Produce Safety Rule (PSR) are expected to remain the same.

How do the water requirements affect my ability to use overhead cooling for sunburn prevention in my apples?

Scientists from University of California, Davis, Washington State University and WTFRC have sampled water quality in recent years.

Those studies show the risk of contamination of fruit via overhead cooling is likely low given the low concentrations of E. coli found in participating irrigation districts over the past five years combined.

The regulatory thresholds initially proposed by the Produce Safety Rule were based on the rate of illness in people following recreational exposure to water at different levels of E. coli, but no such studies have been performed for human exposure to irrigation water, much less exposure to apples that have been overhead cooled using irrigation water. So, unfortunately, we cannot know what a “safe” level would be.

As WSU and WTFRC can attest, the time of survival for E. coli on an apple skin is highly correlated with starting conditions.

If you start with a lot of bacteria, it takes a while for it all to die off. One WTFRC-funded study by Hanrahan and collaborators showed that once a surface was contaminated with generic E. coli, the bacteria remained on the fruit surface within detectable levels for a considerable amount of time.

Experimental data on mature Gala and Golden Delicious suggests E. coli was reduced at a rate greater than or equivalent to the 0.5 log per day reduction proposed by FDA for overhead evaporative cooling treated varieties for at least four days after inoculation when applied within one week of commercial harvest.

Additional treatment with overhead, evaporative cooling did not appear to impact survival of generic E. coli on apples within the first four days after inoculation, compared to the response on control apples that did not receive overhead cooling application.

(For more on the study, see “The cooling effect” in the March 1 issue of Good Fruit Grower. The final report is available at in the searchable database, keywords apple and irrigation.)

In summary, can you still use evaporative cooling? According to the results of the WTFRC study, it is safe to use evaporative cooling, at least in Washington, when applied in the right conditions and when utilizing good practices.

What do I need to consider when determining a suitable water sampling site for my farm?

You don’t need to sample from the canal if the water goes through a weir, pipe and filters before it hits your system.

Sample where it hits your system!

For example, it could be the pump or spigot/valve in your orchard.

You will have to inspect your system and your source though as part of the required environmental assessment, so you’re going to want to walk up to the canal and see what’s going on anyway.

For more on water sampling, see “Simple steps for water sampling” in the July 2016 issue of Good Fruit Grower, and refer to “Water sampling done simply,” a summary prepared by UC Davis and WTFRC scientists to help growers with water sampling, found at •

Videos from the 2017 FSMA Water Quality Testing Workshop

Please contact Jacqui Gordon (; (509)452-8555 ) with the Washington State Tree Fruit Association for questions on food safety training opportunities, Kate Woods ( with the Northwest Horticultural Council for questions on the FSMA law and its requirements, and Ines Hanrahan ( of the Washington Tree Fruit Research Commission for information on research related to FSMA and food safety. Partyka is a research ecologist with the Western Center for Food Safety at UC Davis.