
SOUTH DAKOTA 
Weather and Water Conditions 
D:ought conditions of the past two years still prevailed 
during the early spring of 1957. However, in mid-May, moderate but 
continued rains greatly improved water conditions for the entire State, 
The annual mid-May survey showed an average, State-wide 
density of 5.04 water areas (all types) per square mile. The 1957 density 
was 75 percent above the 1956 average density of 2.88 water areas per 
square mile, and 5 percent above the 1950-56, seven-year average of 
4,80 water areas per square mile. 
The physiographic distribution of water areas is shown in 
Table 1. | 
Favorable water conditions prevailed throughout South 
Dakota following the breeding population survey in May. Above normal 
temperatures during early July, however, reduced water levels consider- 
ably. 
The average East-River mid-July water area density (ex- 
clucing streams) was 3.02 water areas per square mile. This represents 
a 49 percent increase over the 1956 East-River mid-July density of 2.02 
water areas per square mile, and is 31 percent above the 1953-56, four- 
year average of 2.30 water areas per square mile. 
Table } - Mid-May Physiographic Distribution of Water Areas of all Types, 
and 1956 to 1957 Trends" 
Total Water Areas 


Physiographic Per Square Mile 
D:visiorn R. Tee ie 1956 Deen, BK Pe te 1957 Change 
Mizuescta Valley 4.22. 9,62 +128% 
Prairie Hilis 4,45 S23 5 + 88% 
James River Valiey 5,051 Orie +125% 
Missouri Hills 2.69 4,15 + 54% 
Missouri Plateau 2.49 3.74 + 50% 
State-wide Total 2.88 5.04 + 75% 


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