April 2011 article: “Biophysical-Regulatory Classification and Profiling of Streams Across Management Units and Ecoregions,” by Brian S. Caruso and Joshua Haynes.
The National Hydrography Dataset (NHD) in its data-augmented form, NHDPlus probably is the most critical tool in use today for evaluating the state of U.S. waters. But, how good is it, and does it include all the waters of concern? In this paper, streams in semiarid USEPA Region 8 wereclassified based on hydrologic permanence and stream order using NHDPlus and GIS to provide information across broad spatial scales to aid with jurisdictional determinations (JDs).
Here’s what they found: “Based on actual JDs and field information, stream order in the NHDPlus and NHD derived classes is generally accurate, although many first order streams are present that are not indicated in the 1:100k dataset or stream class lengths, and some may also not be in the 1:24k dataset. Similarly, some intermittent or ephemeral streams, especially first order, are not included in the 1:100k dataset or stream class lengths, and some may also not be in the 1:24k dataset. Most of the intermittent streams will require further investigation to evaluate flow duration and/or significant nexus to determine jurisdiction. NHDPlus or NHD have the quality to serve as the primary reference for many perennial stream JDs, but may not for intermittent streams due to errors, omission problems (especially in headwaters), and lack of needed information on flow duration and significant nexus. However, without stream classes or NHDPlus/NHD data, no preliminary information on stream order or flow permanence would be available and field and flow information would typically need to be collected and evaluated for almost every stream for JDs.”
[Please note: I have quoted and paraphrased freely from the article, but the interpretation is my own!]