Estimated Perennial Streams in Idaho

Perennial streams in Idaho have been modeled using regression
equations for 7-day, 2-year low flows (7Q2) described in Wood
and others (2009, U.S. Geological Survey Scientific Investigations
Report 2009-5015). The model produces "synthetic" streams
based on 10-meter resolution digitial elevation models that have been
processed to agree closely with 1:24,000-scale National Hydrography
Dataset flowlines. Lines having attribute PerCode = 1 represent model
grid cells having 7Q2 flow estimates between 0.1 cubic feet per second
(ft3/s) and 0.1 minus the standard error for the applicable regional
regression equation. Lines having attribute PerCode = 2 represent model
grid cells having 7Q2 flow estimates between 0.1 ft3/s and 0.1 plus the
standard error for the applicable regional regression equation. Lines
having attribute PerCode = 3 represent model grid cells having 7Q2 flow
estimates greater than 0.1 ft3/s plus the standard error for the
applicable regional regression equation. These three categories of lines
indicate approximate levels of uncertainty in the model results, with
lines having PerCode = 1 representing the most uncertainty, and lines
having PerCode = 3 representing the least uncertainty with respect to
representing a perennial stream.