Wetland Function and Value

Here we attempt to assess the different functions that certain wetlands have in the whole ecosystem. In other words, what do wetlands do for the environment and how are they perceived by society?

Duluth Area Wetlands Inventory (D.A.W.I.) for wetland assessment

The mapped information provided on the GIS data download page can aid in making a preliminary wetland assessment using St. Louis County's Wetland Assessment Guide, referred to by the acronym SWAG. A description and on-line version of SWAG are located at: http://www.co.st-louis.mn.us/planning/wetland/default.asp.

SWAG was developed for use in St. Louis County, Minnesota in conjunction with the County's Comprehensive Wetlands Management Plan. SWAG is a modification of the Wetland Evaluation Technique (WET) developed by the U.S. Army Corps of Engineers, and also uses elements of Version 1.0 of the Minnesota Routine Assessment Method for Evaluating Wetland Functions (MnRAM). It evaluates the following seven wetland functions:
1. Floodflow alteration: the function whereby surface water is stored or its velocity is attenuated to a great degree than typically occurs in terrestrial landscape.
2. Sediment stabilization: the ability to effectively bind soil and dissipate erosive forces.
3. Groundwater recharge: where recharge to groundwater exceeds groundwater discharge and/or the rate of recharge exceeds the rate of recharge from terrestrial landscapes.
4. Groundwater discharge: where the rate of discharge from groundwater into the wetland exceeds the rate of recharge.
5. Sediment/toxicant retention: where inorganic sediments and/or chemical substances generally toxic to aquatic life are physically trapped and retained.
6. Wildlife habitat (diversity & abundance): the number of different species (diversity) and number of individuals within each species (abundance)
7. Aquatic habitat (diversity & abundance): the number of different species (diversity) and number of individuals within each species (abundance), focusing on fish and invertebrates confined to the water and saturated soils.

Contact: For more information about SWAG, contact Scott Smith, St. Louis County Planning Department.

How to use D.A.W.I. for wetland assessment

A wetland assessment is best conducted by field investigation by an individual with a basic knowledge of wetland science, but the mapped information provided by the Duluth Area Wetlands Inventory (D.A.W.I.) and other GIS sources provided on the Duluth Natural Resources Inventory web page can provide preliminary answers to several of the questions asked in St. Louis County's Wetland Assessment Guide (SWAG).

1. Click on the function of interest below.
2. Each row in the table refers to a question in SWAG for that function. The GIS files needed to answer each question are listed in the second column of the table. Questions that can only be answered by field inspection are noted.
3. Download the GIS files needed from this page...
Wetlands.shp = NRRI's Duluth Area Wetland Inventory (D.A.W.I.) Wetlands
Forests.shp = NRRI's Duluth Forest Inventory (D.F.I.) Forest Cover
Tncstreams.shp = TNC Streams
DRG = USGS DRG's in Geo-Tiff format (= the information shown on a topographic map)
4. Use ArcView or ArcExplorer to display the maps
5. Answer the question as directed in "How used." Where applicable, consult the "Data type" listed to determine a classification code for the wetland or land use feature.
6. Use the answers obtained with the guidance in the on-line version of SWAG to do the preliminary wetland assessment for that function.


Additional Wetland Maps

These wetlands are important because they are part of a larger "wetland complex". This means that water flowing through these wetlands is directly influenced by upstream wetlands, or directly influences wetlands downstream. Here is a map showing these critical wetlands.
(click on map for a closer look)

City wide maps...
These maps show the distribution and location of the five major wetland types...

A description of these five types can be found here.

aquatic bed
emergent
forested
scrub/shrub
unconsolidated bottom

 

These maps show a closer look at the wetlands in the designated city forest parks...

city park index