24 Wisconsin Academy of Sciences, Arts and Letters. 
from ten to twenty feet as maxima along the lines of sounding, 
but gradually deepens as one goes toward the lower end. At 
the boundary between Pierce and Pepin counties the maximum 
depth is thirty-two feet. At Lake City, Minnesota, it is 
thirty-seven feet very close to the government light. At the 
lower end of the lake, the maximum depth of fifty-six feet is 
found close to the Minnesota shore, while the- Wisconsin half 
of the lake, and the river below, are very shallow, probably due 
to the checking action of the Chippewa River, which enters the 
Mississippi from the Wisconsin side, about one mile below the 
foot of the lake. 
The chief source of the water of Lake Pepin is of course the 
Mississippi itself, but it also receives considerable volumes from 
the Isabel and Rush rivers and Pine Creek, on the Wisconsin 
shore, and from a creek just north of Lake City on the Minne¬ 
sota side. 
Let it be stated right here that Lake Pepin is a lake in every 
sense. The very accurate surveys of the Mississippi River 
Commission have disclosed no difference of level between the 
two ends, nor any perceptible current. The lake itself has a 
considerable retarding effect on the Mississippi above it; the 
river near the lake has a fall of a little less than one-tenth of a 
foot to the mile. 
We have here, then, a typical lake, one of the largest in 
Wisconsin (excepting of course the Great Lakes) and moreover 
one whose general physical characters are not only very well 
known, but are constantly being kept track of. This is en¬ 
tirely due to the fact that the lake is part of the channel of the 
Mississippi River, and as such a highway for steamboat trans* 
portation. The Mississippi River Commission has constructed 
a map of the lake in three sheets, on a scale of one to twenty 
thousand, or about three and one-quarter inches to the mile. 
These maps give contours as well as other natural and cul¬ 
tural features of the shore. At intervals of rather less than 
a quarter of a mile, there are lines of soundings from shore 
to shore, soundings along each line being indicated at intervals 
of about one hundred and fifty feet. The character of the bot¬ 
tom is also frequently noted. The Commission maintains 
