WSP05004

• File Number: 8510.100.60
• Description: Rio Grande Compact Commission
• Basin: Rio Grande
• Water Division: 3
• Date: 1/1/1981
• Title: Report of the Rio Grande Compact Commission 1981
• Water Supply Pro - Doc Type: Report/Study

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32 RIO GRANDE COMPACT COMMISSION REPORT

ACCURACY OF RECORDS

The Rules and Regulations of the Commission state that the equipment, method, and frequency of
measurement at each gaging station shall be sufficient to obtain records at least equal in accuracy
to those classified as "good" by the U.S. Geological Survey. Within the physical limitations of
stream gaging, the agencies obtaining the records at Compact gaging stations have complied with
these regulations.

The accuracy of discharge data depends primarily on (1) the stability of the stage-discharge
relation or, if the control is unstable, the frequency of discharge measurements, and (2) the
accuracy of observations of stage, measurements of discharge, and interpretation of records.

The station description states the degree of accuracy of the daily records. "Excellent" means
that about 95 percent of the daily discharges are considered to be within 5 percent of true value;
"good" within 10 percent; and "fair" within 15 percent. "Poorn means that daily discharges have
less than "fair" accuracy.

The phrase "within 5% of true value" used to qualify "excellent" records establishes the
extremes of the prObable errors for 95% of the days in a given period of time. The word "within"
defines the range of errors with individual daily values falling between 95% and 105% of true
value. The probable error in a monthly or annual mean discharge depends more on the distribution
of the daily errors between these two limits than it does on the limits themselves. For this
reason monthly and annual records are much more accurate than most daily records.

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