work. The elements they tested for and the 

 methods used were as follows: 



a. Iron - Thiocyanate method, refer- 

 ence (_12), 9th Edition. 



b. Copper - Carbonate procedure, 

 reference (19) . 



c. Zinc - "Colorimetr ic Determina- 

 tions of Traces of Metals" by 



E. B. Sandell, p. 458. 



d. Aluminum - reference (19) , 9th 

 Edition, p. 50. 



e. Calcium - flame photometer against 

 standards. 



f. Magnesium - reference ( 19) , titan 

 yellow. 



g. Sodium - flame photometer. 



h. Potassium - flame photometer. 



i. Lead - Sandell dithizone method 

 (modified) . 



j. Manganese - reference (19) , 

 periodate method. 



k. Silver - Sandell, dithizonate 

 method, p. 400. 



daily analysis of each sample. This becomes 

 a virtual impossibility when the number of 

 samples and constituents tested for are 

 large. Collection of daily samples by a 

 local resident of the area is a good and an 

 inexpensive way to get numerous samples. 

 It has the disadvantage of not permitting 

 a test for dissolved gases, ammonia, phos- 

 phates, etc. and the samples have been 

 stored for a considerable period prior to 

 analysis which will affect pH, alkalinity, 

 turbidity, nitrate and solids values. 



On this contract, because of the large 

 number of sampling stations involved, be- 

 cause of the necessity of measuring dis- 

 solved oxygen et cetera at each station, 

 and because of a limited budget, it was not 

 possible to get frequent samples at each 

 station. Stations were sampled (composites 

 at each station of two or more individual 

 samples) with a frequency of at least once 

 a month in the winter and up to 10 times in 

 the summer months. 



Hydrogen Ion Concentration (pH) 



These values were measured in the 

 field at the time of sampling with colori- 

 metric indicators cind also with a portable, 

 battery operated, glass electrode pH meter. 

 The glass electrode method usually gave pH 

 values from 0-0.4 units higher than those 

 given by the colorimetric method. Colori- 

 metric values would differ by 0-0.2 units, 

 depending upon the indicator used. 



RELIABILITY OF WATER QUALITY DATA 



The water quality of a stream is con- 

 tinuously changing. In a given stream, the 

 value of the constituent tested for will 

 vary with the rate of strecim flow, with the 

 water use and with the air temperature or 

 season of the year. To obtain a reliable 

 documentation of the water quality, one has 

 the problem of determining how many and how 

 frequently water samples should be collected. 

 In their 12 established sampling stations 

 in the Columbia River Basin, the U. S. Geo- 

 logical Survey normally collects a water 

 sample each day. These samples for three 

 10-day periods are composited in ratio with 

 each sample's conductivity. Thus, three 

 constituent values are determined during 

 each month of sampling. Even with these 

 numerous samples, there are abrupt changes 

 at some stations in the constituent values. 

 The most accurate procedure would be the 



All of these pH values are at best, 

 approximations, for the following reasons: 



1. Colorimetric methods are subject 

 to error from color perception of 

 the observer, deterioration of 

 the standards or the indicator and 

 from pH alteraticns by the indi- 

 cator in poorly buffered samples 

 of water (_12). 



2. Electrometric methods are affected 

 by temperature of the sample. As 

 the sample warms, the pH will rise 

 because of an increase in ioniza- 

 tion in the sample and because of 

 the nature of the electrodes them- 

 selves. This change in tempera- 

 ture was compensated for with the 

 meters used when the water tem- 

 perature was well above 10° C. 

 When the water temperatures were 



