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Stream flow data are prepared by applying a stage-discharge
rating to the recorded stage. We use techniques similar to the U.S.G.S. and the
accuracy of our records is affected by similar factors. The accuracy of stream
flow records 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 measurements of stage, measurements of
discharge, and interpretation of records. Many of the streams we gage have
hydraulic controls that change seasonally, or change as the result of high
flows, or are affected by human activities. For this reason, although many
periods have higher accuracy, in general accuracy should be considered to be
within 15% of true, except for estimated periods, which are less accurate.
Equipment failure or freezing weather causes occasional gaps in the stage
record. For many of these periods, we have estimated the mean daily discharge
from site visit observations, rainfall records and comparing nearby and similar
streams. These estimates are made to give continuity to the record and enable
the calculation of monthly and annual mean discharges.
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