United States Department of the Interior
GEOLOGICAL SURVEY
WASHINGTON, D.C. 20242

Code: 4300 6016

February 28, 1972

WATER RESOURCES DIVISION MEMORANDUM NO. 72.108

Subject: WATER QUALITY - Reporting daily mean suspended-sediment concentrations for days of zero flow

This memorandum supersedes WRD Memorandum No. 72.27, dated August 17, 1971, entitled, “WATER QUALITY - Reporting daily 
mean concentrations for days of zero flow.”

In the Daily Values File of the Water Resources Division’s National Water Data Storage and Retrieval System, failure 
to store a value for suspended—sediment concentration will result in an indication of “no information” for that day 
(shown by dashes in the output table) in the suspended—sediment load column. For days of zero flow, this indication will
be incorrect because the load is zero. 

In order to avoid the error described above, the following procedures should be used when entering data for suspended—sediment
concentrations for days of zero flow:

     If a value for concentration is available based on a sample collected from a pond or pool, place that value
     in the storage file. This value, in combination with zero flow, will result in the computation of zero suspended 
     sediment load for the day.

     If no measured value of concentration exists for a day of zero flow, a value of zero should be placed in the
     storage file. This will also result in the computation of a zero load for that day.

At the present time, this convention will be used only for suspended— sediment data.

If, in your opinion, similar conventions for days of zero flow are needed for other parameters, send your suggestions 
Chief, Quality of Water Branch, for consideration.


G. W. Whetstone
Assistant Chief Hydrologist for
Scientific Publications and 
Data Management


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