WATER QUALITY - Quality control of water analyses: Water-quality service units and mobile laboratories November 28, 1969 QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM N). 70.07 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 necessary. This procedure should be repeated about every six months, or more often if it seems necessary. W. H. Durum WRD Distribution: A, B, FO-LS