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Hydrologic Unit Boundaries

Introduction

This Pacific Northwest Hydrography Framework (PNWHF) dataset provides Hydrologic Unit boundaries levels 1 (region) through 6 (subwatershed) for Oregon and Washington. Some delineation of hydrologic units at the 7th level are also included although these do not represent a coordinated delineation and should be used with the understanding that significant changes could occur in the future. Federal standards for delineation at the 7th level in terms of size class have not been formalized.

The PNWHF Hydrologic Unit boundaries dataset for Oregon and Washington is currently undergoing a pre-certification review in preparation for national Watershed Boundary Dataset (WBD) certification with the Natural Resource Conservation Service (NRCS). In order to accomplish this, the states of Oregon and Washington have been subdivided into 15 "subset" datasets. These datasets undergo an intensive edit and pre-certification review process to ensure that they will pass the national NRCS certification step. NRCS will eventually certify the WBD boundaries for each state when this pre-certification review process has been completed.

In the interim, the provisional datasets that have passed the pre-certification review will be provided for download because they represent the "best available" WBD. A new comprehensive dataset for Oregon and Washington will be provided when the national NRCS certification step has been completed. It should be noted that there is a possibility that boundaries or attribution will be modified in the national NRCS certification step.

Download Data

Two versions of hydrologic boundaries are provided here for download.

• The first is the comprehensive pre-certification 5th and 6th level dataset for Oregon and Washington. This dataset represents the input to the WBD Certification Project. This dataset will become obsolete when the Certification Project is complete.
  
  Download the comprehensive pre-certification Hydrologic Unit Boundaries dataset for Oregon and Washington in ArcInfo coverage format.

• The second version is comprised of 15 datasets that when combined represent all of the boundaries for Oregon and Washington. They are the product of the WBD pre-certification effort and should be considered provisional. They will be forwarded to the NRCS for the national NRCS certification review when completed for each state. Note that the number of downloadable files will increase to the total of 15 as all pass the pre-certification review.

This graphic provides an outline of boundaries and status for the WBD Certification Project in Oregon and Washington - WBD Certification Project Status.

Editing the Hydrologic Unit Boundaries

Maintenance activity currently unavailable.

Helpful Links and References

• National NRCS/USGS protocols for HU delineation
• Interagency Certification Agreement between USGS and PNWHF
• National Watershed Boundary (WBD) dataset website