Clay County has complete and current information about all addresses in the county, including secondary structures. The data is systematically updated based on the normal operations of government. Cities and the county cooperate in ensuring a robust system. This information is used by city and county government offices to support the regular operations and by the local power company to plan for new service hookups. Key information about new addresses is forwarded to the emergency response community on a regular basis.
The county has address data for all existing and planned buildings. It created its address database at the same time it was establishing its GIS. Addresses are now urban-style and follow the Post Office standard. An x-y geographic coordinate is provided with each address so it can be located on maps and on the ground. The coordinate data was originally collected by county GIS staff using GPS receivers. In addition to primary addresses, the county information is collected on secondary structures, like out-buildings and industrial locations, where accidents or other events might occur; this information comprises about 25% of the full database and is available when needed. The original effort to develop the address database, including fieldwork to collect coordinates, took about 2000 hours of staff time.
The County GIS office is the Address Authority and controls new addresses for the entire county. New address data is added based on subdivision plats and building permits. New plats filed with the county must be submitted in electronic format, thereby providing the source of updates to the parcel map. The county’s 11 cities and the county itself issue building permits for new construction on existing lots. Coordinates are added based on parcel centroids from the plats and sketch maps submitted with permit applications. The county GIS office provides addresses for new parcels while the plat is under review and well before construction starts on the new building. Air photos are used to confirm and supplement these sources. The county GIS office budgets about 500 hours a year for managing and maintaining the address system.
Address and coordinate data is widely used within the county by government and the public. It is shared with the local utility companies to help them plan and deliver service to new homes and businesses. It is shared regularly with the local PSAPs (Public Safety Answering Points) to update the address ranges of their Master Street Address Guides (MSAG), used by the E-911 Computer Aided Dispatch (CAD) equipment to identify the appropriate police, fire or other responder. Unfortunately, the coordinate data is not part of the MSAG and is not shared with the contractor that produces the Automatic Location Information (ALI) for individual properties. This means first responders will know the relative location of emergency events but do not have more precise coordinate information to help them find unfamiliar sites.