By Keith Garner

On December 18, 2006, the U.S. Army Corps of Engineers, San Francisco District, announced the publication of the Arid West Interim Regional Supplement ("Interim Supplement") to the 1987 Wetland Delineation Manual ("1987 Manual").  A similar public notice was released by the Los Angeles District on December 22, 2006.  The Interim Supplement provides technical guidance and procedures for identifying and delineating wetlands that may be subject to regulatory jurisdiction under Section 404 of the Clean Water Act within the Arid West Region, which covers all or part of 11 western states, including California.  The Corps believes use of the Interim Supplement will improve the accuracy of wetland delineation in Arid West.

The Interim Supplement will be tested for one-year period starting 30 days from the date of the public notices.  As of that date, the Interim Supplement data forms and indicators must be used for any data collection for wetland delineations.  Field data collected for wetland delineations using the 1987 Manual but not yet submitted to the Corps for review and formal approval will be grandfathered if documentation is provided to the Corps that shows the field data was collected 30 days prior to date of the public notices.

During the interim period, anyone performing a wetland delineation using the Interim Supplement who believes it has resulted in a significantly different boundary line than the 1987 Manual may also complete the delineation using the 1987 Manual and submit both delineations.  The Corps will make the final determination based on analysis of information submitted, which will also be used in the evaluation of the Interim Supplement prior to its finalization.

The Corps Districts will be holding orientation sessions near the start of the growing season to help interested parties become more familiar with the Supplement.  Persons interested in attending these sessions should contact the Los Angeles District or San Francisco District by January 22, 2007, for dates and locations.

Copies of the Interim Supplement are available in higher resolution (27.4 MB) and lower resolution (13 MB) versions.

For more information please contact S. Keith Garner.  Keith Garner, AICP, is an associate in the Real Estate, Land Use and Environmental Practice Group in the firm’s San Francisco office.