18 BULLETIN 1430, U. S. DEPARTMENT OF AGRICULTURE 
no silt-bearing streams emptying into Portland Harbor, and the im- 
proved depths obtained * * * will be practically permanent." 
Although many of the New England streams carry silt, the burden 
is small when compared with that of southern and southwestern 
streams. 
The high spring freshets resulting from the melting of the accu- 
mulated winter snows are followed by well-maintained midsummer 
flow. The relation between the minimum flow and the maximum 
flow is less than 1 to 100. The Connecticut River is the least steady 
of the streams of this group in its flow, because a large portion of 
its basin is located on the steep slopes of the White Mountains and 
other mountains of northern New England, and because of the com- 
paratively small lake surface. 
The Hudson River is similar in general characteristics to the 
New England streams; but its chief tributary, the Mohawk, drains 
a thoroughly cleared agricultural valley, and during freshets bears 
a moderate silt burden. That portion of the river above Troy which 
comes from the Adirondacks nearly duplicates in general character 
the streams of Maine. The silt burden of the Hudson, which has 
increased with the extension of the cleared area, amounts to 240,000 
tons a year, a larger quantity than is borne by the rivers of New 
England, with their better-forested watersheds and better-granu- 
lated soils, but smaller than that carried by the large rivers of the 
southern Appalachians. 
The streams of the Great Lakes region, which include the head- 
waters of the Mississippi River, with the St. Croix, Wisconsin, 
Chippewa, and most other rivers of Wisconsin, Minnesota, and 
northern Michigan, are similar to those of New England in lake 
feeding, but the soils are more sandy ; there is less surface relief and 
while the forest condition of their basins is poorer, the extent of 
forest influences on their flow is less. (PI. 12, figs. 1 and 2.) 
Erosion, on the whole, is so slight in this region that the Missis- 
sippi River above Minneapolis, with a basin of 19,585 square miles, 
has a yearly silt discharge of only 117,000 tons, compared with 
nearly 11,000,000 tons from the Tennessee River with less than twice 
the drainage area of this portion of the Mississippi ; that is, the solid 
burden at the Tennessee River is about fifty times that of this por- 
tion of the Mississippi River. 
The soils of the basins of the streams in the Lake States region 
are prevailingly loose and possess a high storage capacity. How- 
ever, they are locally deficient in cohesion, and where this is the 
case the banks of even small streams corrade during the spring 
freshets. This produces sand bars, especially in some of the streams 
of Michigan, such as the Grand, Au Sable, Kalamazoo, and Muske- 
gon Rivers. There is evidence that erosion of soil from the upland 
denuded of forest has contributed to these deposits, since, and espe- 
cially in the southern portions of these States, there are areas of 
clays and loams which are subject to erosion whenever the surface 
gradient is suitable, although the general setting of grass, the long 
winters, and the moderate summer rainfall contribute to reducing 
it to a minimum. 
Extensive areas in the Lake States are of only marginal value for 
farming, but have been cleared for that purpose. After a futile 
attempt at cultivation, the greater portion of these farms have been 
