PUBLICATIONS - Report--"An evaluation of water-quality records for Texas streams" by J.F. Blakey, R.O. Hawkinson, and T.D. Steele
 


                                      January 22, 1973

QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 73.13A

Subject: PUBLICATIONS - Report--"An evaluation of 
         water-quality records for Texas streams" by J.F. 
         Blakey, R.O. Hawkinson, and T.D. Steele

Over the past 4 years, as part of an effort to assist 
district offices in improving the design and operation of 
water-quality data-collection programs, the Water Resources 
Division has partially funded several pilot studies for 
statistically evaluating historical records of water quality. 
The attached report, prepared by the Texas District in 
cooperation with the Systems Analysis Group, is the second 
report in a series which summarizes the first-phase results 
of data analysis for a state-wide study.

In the report, further demonstration is given of the 
advantageous use of specific conductance as an index measure 
of concentrations of the major inorganic solutes in 
streamflow. Estimation of solute concentrations from daily or 
continuous records of specific conductance in conjunction 
with concentration-conductance relationships is presented as 
a preferred alternative to composite sampling for obtaining 
information on monthly and annual solute concentrations and 
loads. Short-term variability and significant long-term 
changes in both the concentrations and the relative abundance 
of dissolved chemical constituents are documented adequately 
by these index measurements. Case studies in the report 
demonstrate the application of statistical techniques for 
assessing long-term changes in stream chemical quality. 
Economic savings resulting from applying the results of this 
study may free funds for the collection of data on numerous 
water-quality variables not adequately covered by ongoing 
data-collection programs.

This report illustrates the need to more adequately define 
the objectives of the various water-quality data-collection 
programs. Once these objectives have been delineated, an 
adequate statistical framework for sampling can be designed. 
We should continually strive to plan data programs on sound 
statistical grounds,that will enable us to make inferences 
and extrapolate information on overall water-quality 
conditions to the greatest possible extent.



                     R. J. Pickering 
                     Chief, Quality of Water Branch

Attachment

WRD Distribution:
A (Regional Hydrologists, 1 copy only)
FO-LS