Swan Lake Water Shed
Morris, Minnesota
Fort
McCoy
Wisconsin
Figure 3. Location map for Minnesota and Wisconsin sampling sites.
0
30
60
90
120
150 m
Station
Figure 4. Sampling grid for Fort McCoy.
sin (44N, 90W), shown in Figure 3, along a narrow
Dr. Brenton Sharratt of the U.S. Department of Agri-
580-m-long trail (Kestler 1996, Kestler et al. 1999). The
culture (USDA), North Central Soil Conservation Re-
trail consisted of a saturated, thawing soil layer over
search Laboratory (Sharratt et al. 1999). The elliptical
frozen ground. Thaw depths were measured at 7.6-m
depression or prairie pothole was about 2 ha in area
intervals along the trail centerline and at 30.50-
m intervals in the right and left wheel paths, which
were approximately 1.2 m off the trail centerline.
m
15
Figure 4 is the typical sampling pattern. A metal
14
rod was used to determine thaw depth by push-
15
13
m
371.0m
ing the rod into the ground until it met resistance
8
12
and by checking the temperature at this interface.
270.5m
7
11
The soil on this trail was classified as silty
Silty
6
10
sand. The trail water content ranged from 8 to
Clay
5
34% with an average of 18.6% and standard de-
9
Loam
viations of 4.4. The optimum moisture content
15
(moisture of the soil when compacted at maxi-
1
Clay Loam
2
16
15
mum density) of the soil mineral ranged from 8.2
m
to 11.4%. The trail consisted of a thin (0- to 10-
3
17
cm) vegetated layer on top of the mineral soil.
18
4
The percent slope of the terrain ranged from flat
19
371.0m
to gently sloping (with a maximum of one short
371.5m
20
Loam
372.0m
section of 10% slope). Trees were present along
370.5m
the sides of the trail, contributing to variations in
shading on the trail surface.
Scale
Swan Lake, Minnesota
N
0
25m
Thaw depths were collected on a shallow de-
pression in the Swan Lake watershed (Fig. 3),
Figure 5. Sampling grid, site contour, and soil map for Swan
near Morris, Minnesota (4541′N, 9548′W), by
Lake Watershed.
4
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