
3. Shallow marshes: In a wet year will commonly contain up to 30 inches 
of water in the spring and will hold water through July. A few areas 
hold no water in years with below-normal precipitation. Alli are too 
wet to cultivate in years with near-normal runoff. Vegetation includes 
the species listed under 1b and hardstem bulrush, softstem bulrush, 
and cattail. Grazing may remove most of the vegetation as these areas 
dry out during the summer, but if undisturbed the vegetation is com- 
plete and dense. 
4, Deep marshes: Contain up to 4 feet of water in a wet spring and often 
hold water all year. In dry years, almost all have some water in the 
‘spring, but: most go dry sometime during the summer. Most of these. 
areas are overgrown with the emergents listed previously, but a few 
have open water during periods of high water levels. Cover is gen- 
erally sparser than that found in the shallow marshes, but varies 
with water levels. 
5. Open water: Contain up to 5 feet or more of water in a wet spring 
and hold at least 3 feet without overflowing either overland or into 
a permeable underground channel. These areas may have a ring of 
marginal vegetation, or the shores may be grazed bare. If marginal 
vegetation is present, it is generally a narrower band than is found 
on such of the class 4 areas as may be temporarily open. Submerged 
plants and duckweeds are abundant. 
It is evident from these descriptions that the classes are not well 
defined and that it would be possible in different years to place almost any 
water area in more than one class. Im addition, there is continuous grada~ 
tion between types of areas, and even after extensive study it is often 
impossible to place one in the proper class. Even local residents who have 
watched a pothole for a number of years cannot be relied on for an accurate 
estimate of its longevity. In relying heavily on the density of plant 
cover in classifying the potholes, weight was given to long-term average 
water levels as they have influenced the vegetation. It should be emphasized 
that "open water" refers only to areas that are open because they are too 
deep to support vegetation. Areas open only because of disturbance belong 
in one of the other four classes. 
All potholes on the study area contained relatively fresh water, al- 
though a few areas of high alkalinity occur in the region. Only two areas 
were influenced to any extent by trees. These were both small (0.02 and 
i O.4 acre ) .] 
Table 3 shows the size and frequency distribution of the potholes on the 
Waubay study area arranged according to these classes. Size refers to all of 
the area within the outer margin of moist-soil vegetation. For an area where 
the vegetation has been removed, the size includes all of the area where the 
soil has been modified by water. 
Even a casual inspection of table 3, as summarized in the lower portion, 
indicates that there is a close correlation between the size of a pothole and 
the permanence inferred by its-position in the wetland classification. Thus, 
14 
