Association of State Wetland Managers - Protecting the Nation's Wetlands.

The Compleat Wetlander: Improved Tools for Identifying Boundaries of Wetlands and Streams

It’s easy to identify the boundaries of lakes and major rivers, but other waters including some kinds of wetlands and small streams can be more difficult.  Wetlands are identified by looking for signs of water (hydrology), water adapted plants and wet soils.  Wetlands are created by the presence of water all or part of the year; but sometimes the water is absent, or if it’s there, it’s not there long enough or often enough to create a wetland.  Therefore the physical presence and/or absence of water, wetland plants and wet soils are examined to identify a wetland.

In the late 1980s four federal agencies had four different wetland delineation manuals—the Corps of Engineers, the Environmental Protection Agency the Fish and Wildlife Service and the Soil Conservation Service (now called the Natural Resources Conservation Service) each had a different manual.  In 1989 they met and agreed on one manual for delineating wetlands.  It was not easy to reach agreement and the creation of the new manual led to substantial controversy as scientists, agency staff, the regulated community, environmental groups and others debated what information should be collected to identify wetland boundaries.  Eventually an agreement was reached to use the Corps’ 1987delineation manual with amendments.  However, there was a recognized need to continue to improve the tools used to identify wetlands.  For example the Corps manual relied on vascular plants to aid in identification of wetlands and vascular plants don’t grow commonly in Alaska—a state of moss and lichens.  As a result, the Corps in partnership with other federal agencies, states, etc. has been working in recent years to develop regional supplements beginning first in Alaska and moving east.  These supplements provide more detailed information about how to identify wetlands in different ecosystems in different parts of the country.  In addition the list of wet (hydric) soils and wetland plants need to be reviewed and revised based on field experience and research.

Wetlands are not the only water resources that present challenges.  Streams do, too.  The ordinary high water mark (OHWM) is an important indicator used in identifying streams and other water bodies.  But streams look different from one area of the country to another because of differences in precipitation, topography, vegetation and proximity of groundwater.  The Corps has published “A Field Guide to the Identification of the Ordinary High Water Mark (OHWM) in the Arid West Region of the Western United States” to help federal and state agencies, permit applicants and others identify the intermittent and ephemeral streams in areas that receive little rainfall annually.

In the first part of 2010 the U.S. Army Corps of Engineers will be leading an effort to update the 1988 National List of Plant Species that Occur in Wetlands (NWPL) by using a publicly accessible website (Note: to get to this website just continue through all the dire warnings about the pop up). The Corps is planning to publish a notice in the Federal Register early in the year to provide an opportunity for scientists, state and federal agencies, the regulated community as well as the public at large to identify plants that should be added or subtracted from the list. It is anticipated that there will be specific scientific data that will be needed to add or subtract a plant from the list.

For more information on identifying wetlands and other waters visit:

Corps Wetland Delineation Manual

Regional Supplements to the Corps Delineation Manual

National Resources Conservation District Hydric Soils webpage

Identifying the Ordinary High Water Mark in the Arid West.

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