WATER QUALITY - Quality control of water analyses: Water-quality service units and mobile laboratories 

                                       November 28, 1969


To:     Regional Hydrologists and District Chiefs, WRD 

From:   Chief, Quality of Water Branch, WRD    

Subject: WATER QUALITY - Quality control of water analyses: 
         Water-quality service units and mobile laboratories

At a recent meeting, the Water Quality Advisory Group 
discussed possible quality control procedures for water-
quality field service units and mobile laboratories. Field 
service units serve districts which do not have a full-scale 
laboratory. Mobile laboratories for streamside and field 
activities are in use in many districts. Both types of units 
may be equipped to determine such parameters as pH, specific 
conductance, alkalinity, hardness, and chloride, and in 
addition prepare standards for calibrating and checking field 
instruments and monitors. Results of analyses performed in 
these units probably will be published in some type of 
report. The Water Quality Advisory Group concluded that a 
quality-control program is necessary for these field service 
units and mobile laboratories.  It was decided that analyses 
performed'by these units should be included in a reference 
sample program administered by the Chief, Analytical Methods 
Laboratory, Denver, Colorado.

The planned quality control program for field service units 
and mobile laboratories is less formal than that currently 
administered for the full scale water-quality laboratories . 
The responsibility for the quality control program will be at 
district level. The district will be expected to determine if 
the work is acceptable. A copy of the analytical results of 
the reference sample should, however, be sent to the Chief, 
Analytical Methods Laboratory.

Upon receipt of this memorandum, WRD Districts with field 
service units and/or mobile laboratories, should request a 
reference sample from the Analytical Methods Laboratory, 
giving the observed range of values for parameters determined 
in the district field service unit or mobile laboratory. 
Also, please furnish the name of the method and instruments 
which will be used. The receiving office will be expected to 
determine only those parameters usually determined in the 
district service unit or mobile lab. It is not possible to 
prepare standard samples for all constituents measured, for 
example, coliform bacteria, dissolvcd oxygen, and EOD. With 
the reference sample thc receiving office will also receive 
the allowable limits of variation for an excellent, good or 
poor rating. Any analyis with a poor rating indicates thal; 
the analysis is below standard and corrective measures are 

This procedure should be repeated about every six months, or 
more often if it seems necessary.

                                   W. H. Durum

WRD Distribution: