Rice Water Seepage Management: Voluntary GuidelinesWhat is seepage?

Movement of water through a rice field levee to an adjacent area.

Why are growers being asked to make voluntary efforts to control seepage water?

The Central Valley Regional Water Quality Control Board and the Department of Pesticide Regulation believe it is important that the rice growing community become aware of the potential impact of contaminated seepage water reaching the agricultural drains and have the opportunity to voluntarily address the problem. If these voluntary efforts are sufficient to minimize the impact of seepage water on the agricultural drains, no future regulatory action will be needed.

VOLUNTARY GUIDELINES

Prevent seepage water from leaving the rice field during the holding period through loosely constructed levees by:

• Running a tractor tire or track on top of existing border levees, and
• Ensuring that newly constructed levees are built with mineral soils (not organic matter and plant residues), adequate width, and soil cores (when building levees, run tractor tire or track on top to firm up core of check). Double berming is another method of containing seepage.
• Using technical recommendations for levee construction offered by the USDA in a handout entitled "Closed Rice Water Management Systems," available from your county agricultural commissioner.

Prevent water in seepage areas from reaching the drains during the holding period by:

• Directing or pumping seepage water to fallow land, and
• Blocking the exit of water from the seepage ditch to agricultural drains.
• Communicate with applicators to establish the common goal of keeping drift away from seepage ditches, drains, border levees, and roads. Dry material on roads and dry ground is considered to be environmental contamination with the applicator liable for a civil penalty. This material remains viable and any runoff from these areas during wet weather should be held on your property to avoid contaminating agricultural drains.
• Prevent leakage from levees by inspecting and repairing rodent damage during the holding periods.