Additional rules and regulations apply to manure management for confinement feeding operations. Iowa law requires confinement feeding operations to retain all manure produced between periods of disposal, and to dispose of the manure in a manner which does not cause surface water or groundwater pollution. Other manure control requirements that apply to confinement operations include:

• Manure shall not be discharged directly into a water of the state or into a tile line that discharges directly to state waters.
  
  
• Operations using anaerobic lagoons or other earthen manure storage structures must maintain a minimum of two feet of "freeboard" at all times. In other words, the liquid level in the structure must never get within two feet of overflowing.
  
  
• Upon closing a confinement feeding operation, the owner must remove and properly dispose of all accumulated manure from the operation's manure storage structures.

Land Application

• Confinement feeding operations larger than a small animal feeding operation (an animal unit capacity of 500 animal units or less) must:
  
  
  • Use a certified manure applicator to apply manure, and
    
    
  • Apply manure at or below the nitrogen use level necessary to obtain optimum crop yields, and
    
    
  • Submit a manure management plan to the DNR each year, and
    
    
  • Keep records of manure application (See form 542-8002 (*.pdf file) Manure Application Recordkeeping Form and Fact Sheet (LINK to forms page)).

The following requirements for land application apply to all confinement feeding operations:

• Using spray irrigation for manure disposal is allowed under state statutes, provided the irrigation operations comply with separation distance and other disposal requirements of DNR rules. However, spray irrigation of manure is not allowed on land located within the drainage area of an agricultural drainage well.
  
  
• Liquid manure disposal from a confinement is also prohibited within 750 feet of certain buildings and public use areas unless:
  • The manure is injected or is incorporated within 24 hours of application, or
  • The manure comes from a small animal feeding operation (has an animal unit capacity of 500 or less animal units), or
  • The manure is applied by low pressure spray irrigation equipment.
  • Other separation distances apply to protected areas such as sinkholes, wells and ag drainage wells. Producers and manure applicators should check the Separation Distances for Land Application of Manure (*.pdf file) to determine which separation distances apply to their operation. Recent changes in Iowa law added water sources and high quality water resources (*.pdf file) as protected areas.

Isolation of Tile Lines
Because a confinement feeding operation must contain all manure on site, tile lines are often an issue of concern. Tile lines can provide a direct conduit to a watercourse or an aquifer, and so they present a clear threat if located near manure storage structures. The owner or developer of a new site is expected to locate, remove and redirect drainage tiles around storage structure sites. In certain cases, an existing facility is required to conduct the same evaluation for drain tiles as at a new site. All confinement feeding operation owners are encouraged to conduct a voluntary effort to identify and isolate drain tiles to reduce the risk of pollution if a containment structure fails.