Water Levels -~ Owing to the late date and the lack of time, water gauges 
were not set up at the beginning of the study. Heavy rains at the end of July 
apparently filled the potholes to capacity and provided a standard by which 
the relative rates of water loss could be read, Forty-feur gauges were 
established within 2 days ef the storm. These were willow sticks driven 
firmly inte the bottom soil and notched at the water surface te provide a 
reference point. The relative rates of fall in water levels of the varieus 
types as measured during the peried from July 30 te August 21 are shown in 
Table 2. 
Area =~ Areas of the petheles as reported in Table 2 were calculated by 
means of a field application of the weight method described by Weleh (1918). 
The outlines of the potholes were transferred from aerial photes (scale: 
3" = 1 mile) te a map at a scale of 8" = 1 mile, The outlines were checked 
in the field to make sure they corresponded to the borders of the potholes as 
indicated by the transition of the vegetation frem meist-seil to upland 
species, This transition line was judged to be more stable than an estimate 
of the high-water mark, Frequent checks of the sise of the outlines were made 
by pacing. 
Table 1. ‘Types ef potholes found on the study area, 
A - Permanent Potholes 
1 - Sedge-whitetep 
2 - Cattail 
3 - Bulrush 
h = Zones of emergents intermixed or denuded 
B = Semipermanent Potholes 
1 = Sedge-whitetop 
2 - Cattail 
3 - Bulrush 
l - Zones of emergents intermixed or denuded 
C - Temporary Waters 
D - Artifieial Dugouts without Fleeded Ends 
Depth -- The depths (Table 2) which were all measured from August 20 
to August 27 are not entirely accurate, as the bottem soil in these areas 
was extremely soft and there was usually seme questien when the bottom had 
been reached. Hewever, they are of some value for purpeses of comparisen. 
Permanence -— Those potholes were rated as permanent which might be 
expected te contain water through the course of the summer even in 
relatively dry years. This is an extremely indefinite criterion, particu- 
larly when one considers the statements by lecal residents that in 1938 the 
only open water on the study area was in one artificial dugout. In actual 
practice potholes were rated as permanent which had a very definite growth 
of emergent vegetation at the margins and open water at the center making 
up 10 percent or more of the total area. In one case, where the 
vegetation had been removed by excessive grazing, the permanency was 
