4200 4014
Auto. Data Section

November 16, 1972

WATER RESOURCES DIVISION MEMORANDUM NO. 73.82

Subject: PROGRAMS & PLANS - Station Identification Numbers

The purpose of this memorandum is to outline the rules for the assignment of station identification numbers.

The Water Resources Division data files permit the use of a standard 8-digit downstream order or a latitude-longitude identifier for station
identification numbers. Each use is described as follows:

Downstream order number

The standard 8-digit (numeric) downstream order number must be used for on-stream stations (except large open-water areas) where
records are to be systematically collected. Examples of stations that meet this criteria are:

1. Regular surface-water stations.
2. Partial-record (surface-water and water-quality) stations.
3. Regular water-quality stations.

The downstream order number is the primary number used for the storage of data for these stations and is maintained for the efficiency of data
retrieval by river basins. Under certain conditions, the downstream order number may change, such as a different stream being designated
as the headwater stream.

Latitude-longitude identifiers

A latitude-longitude identifier must be used for off-stream stations, project stations where the data are to be published in a project-type report,
for on-stream stations where there is difficulty in assigning a meaningful downstream order number, and on-stream sites where data are obtained
intermittently. Examples of stations that meet this criteria are:

1. Water-quality grab sample sites.
2. Wells
3. Surface-water sites at which miscellaneous measurements are made.
4. Large open-water areas (lakes, reservoirs, bays).

The latitude-longitude identifier should be used in the context of a unique number, that is, a number assigned to the site that will never be changed.
This number is not used again or reassigned to another station even if, for some reason, the station is destroyed or removed from service. The
number will continue to be associated in the files with the data from the deactivated site.

The following data files in the National Water Data Storage and Retrieval System have been or are being changed to accomodate the station identifiers as outlined above.

1. Daily Values File.
2. Water Quality File.
3. Digital Recorder File (to be converted to the Daily Values File - work about 70% completed).
4. Peak Flow File (conversion not started).

S.M. Lang
Acting Assistant Chief Hydrologist for Scientific Publications and Data Management

WRD Distribution: A, B, S, FO, PO