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Information Sheet IS-15 Reissued Waste Discharge Requirements General Order R5-2013-0122 Existing Milk Cow Dairies • § 648(c) Requires that milk rooms be floored with concrete or other suitable material and be provided with a vented, trapped drain and §649(a) requires that milk barns be floored with concrete or other suitable material and be sloped to drain; and • § 661 Requires that roof drainage from barns, milk houses, or shelters shall not drain into a corral unless the corrals are paved and properly drained. In addition to the requirements of Title 3, the Dairy General Order requires that milk barns, including their related sprinkler pens and gutters be designed and maintained to convey all water that has contacted animal wastes or feed directly to the wastewater retention system, and that all production area structures must be constructed or otherwise designed so that clean rainwater is diverted away from manured areas, feed storage areas, and waste containment facilities, unless drainage is fully contained in the wastewater retention system. Dairy operators must design and maintain the animal confinement area (including corrals), and manure and feed storage areas in a manner that limits infiltration so that wastes, nutrients, and contaminants generated are directed to the manure retention pond(s). The Dairy General Order prohibits standing water in these areas as of 72 hours after the last rainfall (see Production Area Specification D-6 of the reissued Dairy General Order). Best Practicable Treatment or Control Measures for Land Application Areas Normal commercial farming practices, including the application of dairy wastes to cropland as fertilizer, can contribute salts, nutrients, pesticides, trace elements, sediments, and other by- products that can affect the quality of surface water and groundwater. Evaporation and crop transpiration remove water from soils, which can result in an accumulation of salts in the root zone. Additional amounts of water are often applied to leach the salts below the root zones. These leached salts can cause impacts to groundwater or surface waters. Even using the most efficient irrigation systems and appropriate fertilizer application rates and timing to correspond to crop needs, irrigation of cropland may degrade high-quality groundwater. In addition, in land applications areas where groundwater is shallow, some Dischargers have installed subsurface (tile) drainage systems to maintain the groundwater level below the crop's root zone. Drainage from these systems, which may include constituents originating from the dairies, may be discharged directly to surface water bodies or to drainage ditches that discharge to surface water bodies. Some of these systems discharge to evaporation basins that are subject to waste discharge requirements. With respect to salts and nutrients, the key to limiting degradation and ensuring compliance with water quality objectives at the dairies' land application areas is an effective Nutrient Management Plan, which specifies the volume and composition of the wastewater that can be applied to land application areas without causing adverse groundwater impacts. The Board considers an effective Nutrient Management Plan to be BPTC for the land application areas. The majority of the dairies covered under the 2007 General Order had been operating for many years without a Nutrient Management Plan. In response, the Board required each dairy operator to develop and implement a Nutrient Management Plan, and the reissued Dairy General Order will continue this requirement.