The animal feeding operation data layer was based on Missouri Department of Natural Resources (MDNR) Water Quality Information System (WQIS) database. Only operations that had permits issued after 1980 were included. Members of the steering committee reviewed the list and removed all other operations that they believed no longer had animals. The committee members also provided the location, type of other animal feeding operation, and manure storage system (if known) in the county they were aware of in the county.

This process identified 35 animal feeding operations in Saline County (Table 1). Of the 35 operations, 32 are primarily swine operations, 2 beef operations, and 1 a poultry operation.

The 19 entries from the WQIS database include information on location, animal type(s), animal number, and manure storage facility. Records of the 16 operations not in the WQIS database include only location, animal type(s), and, in most cases, manure storage system.

The Missouri Agricultural Statistics Service has annual estimates of animal numbers in the county (Table 2). This estimate of animal number includes all animals of any size of the particular animal type. For example, all hogs is an estimate of all sows, boars, nursery pigs, and finishing hogs in the county. We estimated current animal numbers based on the 1996 reported values.

The WQIS database includes approximately 76% of the hogs in the county (Table 3). The WQIS database is expected to be incomplete because all data provided to MDNR for Class II and Class III operations is voluntary. We lack specific information on animal numbers in 14 of the 25 Class II and Class III operations included in the animal feeding operation data layer.

The animal feeding operation data layer is likely to be incomplete and contain erroneous information. The WQIS database does contain errors and some permits on file may not be active. Information in the database about Class I operations should be the most accurate because it is typically the most recent, these operations have a regulatory requirement to be a part of the database, and operators are expected to keep their permits current. Class II operations are under no obligation to update information about their operation in this database. In addition, any operations that have been permitted after April, 1998 will not appear in this layer unless added later by the county. We have tried to minimize the importance of these errors through double checking of information with the steering committee.

 Table 3. Estimate of hog numbers accounted for by the MDNR WQIS database.

 Table 4. Summary of data points in the animal feeding operation data layer. All points can be associated with an operation on the map by the identification number in the first column.