2.5.4 Wetlands

Approximately 40 percent of the land area within the Christmas Lake subwatershed is shown on the National Wetland Inventory as wetland (see Table 6), with the bulk of that Christmas Lake. 

Table 6.  National Wetlands Inventory wetlands in the Christmas Lake subwatershed.

Circular 39 Type

Area (acres)

Cowardin Class

Area (acres)

Seasonal

2.0

Emergent

28.1

Shallow Marsh

26.0

Scrub Shrub

0.7

Deep Marsh

1.6

Unconsolidated Bottom

271.2

Open Water

269.7

 

 

Scrub Shrub

0.7

 

 

Total

 300.0

 

 300.0

Source: Minnesota DNR.

In 2001-2003 the District undertook a Functional Assessment of Wetlands 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 6 above, which shows wetland acreage and type from the National Wetlands Inventory completed in the 1980s, Table 7 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 8).   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 7.  Dominant wetland type in the Christmas Lake subwatershed as assessed in the Functional Assessment of Wetlands.

Circular 39 Type

Area (acres)

Wet Meadow

4.9

Shallow Marsh

15.5

Deep Marsh

0.7

Open Water

26.0

Scrub Shrub

1.1

Lakes

255.4

Not typed

1.2

TOTAL

 304.8

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 8.  Wetland management classifications of wetlands in the Christmas Lake subwatershed as determined in the Functional Assessment of Wetlands.

Classification

Number

Area

(acres)

% of total

Preserve

13

33.2

57.2

Manage 1

10

9.4

16.2

Manage 2

8

5.4

9.3

Manage 3

7

10.0

17.3

TOTAL

 

  58.0

 

Note:  The FAW classification excluded large lakes and wetlands less than ¼ acre in size; those areas are included in the NWI, so total will not match Tables 6 or 7.

Source: MCWD 2003 Functional Assessment of Wetlands.  See Figure 12.

The Christmas Lake subwatershed has several large wetlands that are classified in the Preserve category (see Figure 12).  Some smaller wetlands in the southern watershed were rated highly on vegetative diversity or were exceptionally sensitive to impacts from the watershed.  Como Lake in the northern subwatershed was rated as exceptional for fish habitat and aesthetic values, while some fringe wetlands to Christmas Lake were rated as exceptional fish habitat (see Figure 13). 

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.  No wetlands in the subwatershed were identified in the FAW as being of high restoration potential (see Figure 14).  Several were rated as of moderate potential.