Iowa has two types of animal feeding operations (AFOs) regulated under the Department of Natural Resources: confinements and open feedlots. Both AFO types are confined (kept and fed for 45 days or more per year) in a lot, yard, corral, building or other area. Both types of AFOs include manure storage structures, but do not include livestock markets.

A confinement feeding operation confines animals to areas that are totally roofed. Confinement feeding operations in Iowa are not allowed to discharge manure to a water of the state.

An open feedlot is unroofed or partially roofed with no vegetation or residue ground cover while the animals are confined. Large open feedlots in Iowa are allowed to discharge to a water of the state under certain conditions, such as during a storm event larger than the 25-year, 24-hour storm.

Unlike livestock on pasture, animals in AFOs are kept in small areas where feed and manure become more concentrated. Animal manure and urine contain nitrogen (nitrate and ammonia), phosphorus, organic matter, sediments, pathogens, and heavy metals - all of which are potential pollutants if they are concentrated in a small area. Some of these substances can pose threats to human health or impair drinking water. When excess nutrients reach our waters, they can cause low levels of dissolved oxygen, algal blooms and, in extreme cases, fish kills.

Iowa regulates AFOs to protect surface and groundwater resources. All AFOs must follow some regulations when land applying manure or when building a new structure or expanding an existing operation. Generally, regulations differentiate between the type and size of operation, and the type of manure storage that is used.

When constructing an AFO or applying manure, the operations must also meet separation distances from neighboring buildings and public use areas. These distances help protect neighbors from potentially offensive or dangerous odors and air emissions. Environmentally sensitive areas such as wells, sinkholes and water sources are also protected by setbacks from construction and manure application.

The DNR has several sections that work with animal feeding operations:

The Air Quality Bureau is conducting a field study near animal feeding operations to evaluate air quality in rural Iowa. If harmful concentrations of ammonia, hydrogen sulfide, or odors are discovered during the field study, plans and programs to reduce emissions may be developed.

DNR's Wastewater Construction Section reviews applications for construction permits for animal feeding operations. An engineer coordinates this review with the applicant, the applicant's engineer and other DNR staff to assure that all requirements are met before a permit is issued.

The NPDES (or national pollutant discharge elimination system) Section issues operations permits (also called NPDES permits) and storm water permits to animal feeding operations. Staff also provide technical assistance to animal feeding operators. The NPDES staff coordinate with the DNR field office staff when operations permits are issued.