Water: Friend or Potential Foe

One of the most important steps to minimize the risk of bacterial contamination of your harvested crop is to take steps to keep potentially contaminated sources off property, including runoff from areas adjacent to your orchard. It is also critical to prevent pooling of water on the orchard floor and to regularly test your water.

Here are some ways that water can introduce or spread contamination to almonds:

• Contaminated water used for dust controls on roads
• Contaminated water in the tank when making foliar sprays
• Improperly adjusted or broken sprinklers that cause consistent wet areas on the orchard floor
• Septic overflow or effluent discharge
• Water runoff from equipment washing areas
• Water runoff during the rainy season from adjacent landfills or livestock operations
• Moisture buildup in windrows

Water Testing Guidelines

Follow these guidelines to protect your crop from potential contamination:

• Monthly testing of all water sources is highly recommended until sufficient experience with quality, over the course of at least two harvest seasons, is available
• Closed, underground or capped well systems should be tested annually
• Uncapped wells, open canals, reservoirs, collection ponds and recycled water should be tested quarterly
• Maintain copies of all water quality reports
• Test water for possible microbial contaminants
• Follow mitigation measures for generic E. coli detection level if “present” or “positive”
• Irrigation water standards have no established maximum contaminant level for microbiological contaminants but current research suggests that a single point maximum for generic E. coli of 126/100ml is a useful threshold that can be easily met in most irrigation sources of California. See the Water Quality and Source section of Good Agricultural Practices for Almond Growers for additional guidelines.