2.5.4 Wetlands

Approximately 28 percent of the land area within the Langdon Lake subwatershed is shown on the National Wetland Inventory as wetland (See Table 5). 

Table 5.  National Wetlands Inventory Wetlands in the Langdon Lake subwatershed.

Circular 39 Type

Area (acres)

Cowardin Class

Area (acres)

Seasonal

0.6

Emergent

72.4

Wet Meadow

0.9

Forested

0.8

Shallow Marsh

71.2

Scrub Shrub

7.2

Deep Marsh

30.2

Unconsolidated Bottom

213.3

Open Water

183.0

 

 

Scrub Shrub

7.1

 

 

Forested

0.7

 

 

Total

293.7

 

293.7

Source: Minnesota DNR.

In 2001-2003 the District undertook a Functional Assessment of Wetlands (FAW) on all wetlands greater than one-quarter acre in size.  This assessment used a variant of the Minnesota Routine Assessment Method.  In contrast to Table 5 above, which shows wetland acreage and type from the National Wetlands Inventory completed in the 1980s, Table 6 below shows the acreage and type as assessed in the field.   Using the results of that analysis, individual wetlands were assigned to one of four categories – Preserve, and Manage 1, 2, or 3 (see Figure 12 and Table 7).   Wetlands that were evaluated as Exceptional or High on certain ecological or hydrologic values were assigned to the Preserve category.  The balance of evaluated wetlands were assigned to a category based on this assessment of current functions and values, with Manage 1 wetlands exhibiting higher values and Manage 2 and 3 moderate or lower values.   Refer to the Functional Assessment of Wetlands (2003) for details of methodology, classification, and management recommendations.

Table 6.  Dominant wetland type in the Langdon Lake subwatershed as assessed in the Functional Assessment of Wetlands.

Circular 39 Type

Area (acres)

Seasonal

34.6

Wet Meadow

12.3

Shallow Marsh

25.8

Deep Marsh

57.8

Open Water

64.4

Scrub Shrub

3.6

Not typed

4.6

TOTAL

 203.1

Note: Based on field assessment.  Excludes those areas determined in the field not to be wetlands, and stormwater ponds clearly excavated out of upland.   Includes some small areas that were not field assessed.

Source: MCWD 2003 Functional Assessment of Wetlands.  See Figure 11.

Table 7.  Wetland management classifications of wetlands in the Langdon Lake subwatershed as determined in the Functional Assessment of Wetlands.

Classification

Number

Area (acres)

% of total

Preserve

11

157.5

83.1

Manage 1

10

11.3

6.0

Manage 2

19

12.0

6.3

Manage 3

15

8.7

4.6

TOTAL

55

189.5

 

Note:  The FAW excluded large lakes and wetlands less than ¼ acre in size; those areas are included in the NWI, so total will not match Tables 5 or 6.

Source:  Minnesota DNR.

The Langdon Lake subwatershed has several large wetlands –Saunders Lake, Black Lake, and wetlands riparian to Langdon Lake – that scored highly on vegetative diversity, fish and wildlife habitat, or aesthetics (Figure 13) and thus are classified in the Preserve category (see Figure 12).

Some of the wetlands were also evaluated for restoration potential.  Factors considered were the ease with which the wetland could be restored, the number of landowners within the historic basin, the size of the potential restoration area, the potential for establishing buffer areas or water quality ponding, and the extent and type of hydrologic alteration.  There are four wetlands in the subwatershed that were identified as being of high restoration potential.  Three are located in Gale Woods Regional Park.  There are also several wetlands of moderate restoration potential located in the western subwatershed (see Figure 14), including the Black Lake wetland complex.