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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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