Seepage can occur through levees into adjacent dry fields or into existing drains and canals. Leakage caused by crayfish and rodent burrowing is not considered seepage, but can also result in the movement of irrigation water off rice fields. Seepage is the movement of water from a flooded rice field into an adjacent, nonmanaged area. Occasionally, seepage appears as a wet area that can damage a perimeter road. Unwanted seepage in ditch near and around drain during the holding period.
Seepage can occur directly from a field into an adjacent drain or canal.
This seepage may be difficult to recognize, but the inability to maintain water depth may indicate that seepage is occurring. Checks or fields that use significantly more water than others, even though soil types are comparable, may seep. Seepage can be the source of excessive water use and difficulty in maintaining uniform water levels when the best water management practices are used. Seepage water that contains high concentrations of pesticides can hinder efforts to comply with California's stringent water quality goals. Efforts to meet these goals depend on long holding periods, which allow pesticides to dissipate almost completely in rice fields before release.