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Proper AFO Siting

Proper Siting of an Animal Feeding Operation
using karst terrain and alluvial soils maps


The DNR has developed the AFO Siting Atlas to help livestock and poultry producers who are planning a new animal feeding operation, or the expansion or modification of an existing operation. These maps give a quick overview of the landscape features that must be considered when planning construction. The maps can be especially helpful in determining where alluvial soils, and thus potential floodplain areas; and karst topography and sinkholes.Flooded road

Iowa laws have specific requirements for building, expanding or modifying open feedlots and confinement feeding operations located in the 100-year floodplain. Knowing if a potential site has alluvial soils is one step in determining if the site could be in a floodplain and if building restrictions could apply. Depending upon specific site conditions, construction may be prohibited or a floodplain permit may be required.

All animal feeding operation structures have a "high damage potential," meaning flood protection (both structural integrity and elevation of the lowest opening) must be provided to the level of the 100-year floodplain plus one foot. In addition, the construction must allow for the conveyance of flood flows.
Karst terrain
Iowa law also prohibits placing confinement feeding operations within 1,000 feet of a sinkhole, and sets specific separation distances from other protected waters. Animal producers who plan to build, modify or expand a confinement feeding operation structure will need to find out if the proposed location is in karst terrain.

Use the AFO Siting Atlas to evaluate potential sites for environmental concerns.

AFO Siting Atlas

Map of karst and sinkholes
The animal feeding operations (AFO) Siting Atlas was created because of requests from the livestock industry. It’s designed to help producers evaluate potential locations for livestock and poultry sites. Producers, consultants and DNR staff can quickly locate a potential site and determine if a new or expanding facility is likely to be located on alluvial soils; or if a confinement site is proposed in karst terrain.

Alluvial soils and karst describe areas in Iowa that may be highly vulnerable to flooding or groundwater contamination. Alluvial soils were formed in materials that were deposited by running water, thus it is possible that a site located in alluvial soils is located in a floodplain. Karst terrain refers to those areas that have soluble bedrock close to the ground surface. Karst areas are often characterized by sinkholes and losing streams. Water and contaminants in these areas can travel quickly through underground passageways to wells, springs, and streams.

Refer to the Mapping (Interactive) pages for general information about using interactive maps or use the specific instructions below for the AFO Siting Atlas. Check proper AFO siting for more information on regulations.

Instructions for using the AFO Siting Atlas to check for potential alluvial soils or karst

Navigating the interactive map: Go to the Animal Feeding Operations (AFO) Siting Atlas then click to enter.
  1. Click on a location on the map to estimate AFO site parameters.
  2. Locate the site and determine whether the site is in “potential alluvial soils” or within 1,000 feet of a mapped sinkhole"  or in "potential karst".
  3. You will need to print out the map for documentation. To print an image of your site, go to File – Print in your web browser.


Map interpretation and documentation

Since it was impossible to analyze the soil and subsurface properties of every piece of land in Iowa, the Iowa Geologic Survey created maps that contain all of the potential karst and potential alluvial areas in the state. Producer who wish to locate a site in these potential areas will have to consult with an engineer, soil scientist or qualified staff from the USDA Natural Resources Conservation Service to confirm the mapping or submit documentation to refute the alluvial or karst mapping. Additional information about this process can be found in a fact sheet under AFO Resources. 

Alluvial soils. If the footprint of the proposed confinement or manure storage structure is within "Potential Alluvial Soils" (area shaded blue), please contact the DNR Flood Plain section at 866-849-0321.

Karst terrain. If the footprint of the proposed confinement or manure storage structure is within "Karst" or "Potential Karst" (areas shaded red and purple), please contact the DNR animal feeding operations permitting engineer at 712-262-4177.

Producers/Consultants: To document the determination, please attach a printed copy of the map, with the footprint of the proposed structure marked clearly, to the appropriate materials:
  • Permitted confinements - Submit with construction permit application and send to DNR field office in Spencer.
  • Non-permitted confinement sites - Submit with MMP and send to the appropriate DNR field office.
  • SAFOs (small animal feeding operations) do not need to submit documentation, but should keep a copy with their plans.
If you receive correspondence from the DNR Flood Plain Section, please include a copy of that correspondence with your submitted materials.

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