WATER ANALYSIS--Color Determination


                                   April 2O, 1970

QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 70.11

To:      Regional Hydrologists and District Chiefs, WRD

From:    Chief, Quality of Water Branch, WRD

Subject: WATER ANALYSIS--Color Determination

Quality of Water Branch Technical Memorandum 70. 02, 
September 4, 1969, listed Color as one of the 19 
determinations to be performed on sample No. 4 -- an 
unfiltered, well-mixed sample. The term, Color, without 
additional definition, means "true" color -- that is, the 
Color of water from which turbidity has been removed. Recent 
inquiries indicate some confusion concerning the Color 
determination. That portion of the sample to be used for the 
Color determination should be clarified by centrifugation or 
settling before analysis. Removal of particulate matter by 
filtration is to be avoided because filtration tends to 
remove "true" Color from water (Rainwater and
Thatcher, WSP 1454, Page 155, 1960).



                                       W. H. Durum

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