The cooperator stations are designed as part of a grided climatological network where stations are located one per 25 mile grid and these are designated as A stations. Stations that report water stage levels are part of the hydrologic program and are classed as B stations. Stations that are in the same grid as an A station or have some instrumentation that is different from that described in this document are classed as a C station , called meteorological or public service stations. Stations can also be classified as ab ac bc or abc which served more that one program and have both climate equipment and water stage measuring equipment. Data from C stations may be collected but not put into the data base system and show up on the station history report as non published stations. Cooperator stations have sponsors such as the Corps of Engineers that give money to  NWS to maintain the station. Not all stations have sponsors.

The cooperator station is located in an area containing cover typical of the surrounding area. 

Cooperative Station are identified by a 6-digit number. The first two digits designate a USA state or territory code. The last four digits are assigned to stations within a state in general accordance with the alphabetic order of the station name. A station in this network, as designated by a single Cooperative Station Identifier, can be one site or a series of sites whose locations fall within 2 miles horizontal or 100 feet vertical difference. Consequently, the station can be moved but does not get a new number if the location change is less than 2 miles or 100 feet vertical change. Station name or number may have records at NCDC that are not currently active because the station has moved or been discontinue because the cooperator no longer wished to take the measurements.