248 NAVIGABILITY OF THE MISSOURI. 
about five miles below Fort Benton. Immediately above the site of the old Fort McKey another 
rapid occurs, twenty inches water on the bar; and one opposite Burnt island, about twelve miles 
below Fort Benton, with twenty-two inches on the bar. There is no other obstacle upon either 
of these bars than want of water. A rapid known as ‘“Publieus,” a few miles below, had 
twenty-three inches of water on the bar, but a clear channel. Another without a name, a few 
miles below this again, had two feet on the bar, but this season had several large rocks near the 
channel. But the worst point in the whole river, with the exception perhaps of the one first men- 
tioned, is one which goes by the name of ‘‘Dauphine’s”’ rapid, about sixteen miles below the 
mouth of Dry river. Here a gravel bar extends across the whole river, and a small gravel island 
near the middle divides the stream into two branches, of nearly the same depth, and causes 
a bend in the channel of both; in addition to this, boulders of a ton weight are frequently 
found in and near the channel. The depth of water in the channel was twenty inches; 
its rate did not exceed four and a half miles per hour. The current is stronger here than 
at any other point on the river. There were several other rapids below this, but of no con- 
sequence as compared to it. From this point, which is about sixty miles above the mouth of 
the Muscle Shell, the river-sand begins to alternate with the gravel of the bottom, and the rapids 
and shallows become less frequent and the channel better; and, as we approach the mouth of 
the Muscle Shell, the river begins to assume the characteristic appearance of the Missouri in every 
respect; and below its mouth all obstacles to navigation for small boats may be considered at an 
end. Its width gradually increases, and near the mouth of the Milk river its general width is 
about four hundred yards. 
The above statements refer to the river between the 20th and 30th September. Earlier in the 
season, when its tributaries are supplied from the melting of the snows in the mountains, its 
depth is much greater. In the month of June it has about three feet more water; from the first 
of August to the middle of September it falls very gradually, and upon the first of September the 
depth is about one foot greater. This rise and fall of the river is very regular, and it is but little 
affected by accidents of weather. During the high water the current is very rapid and severe, 
and the small rapids are lost sight of. As to the large rocks sometimes found in the channel, 
they are brought from high up the river by the ice as it goes out when the river breaks up. 
During the winter they become attached to the under surface of the ice, and in its removal they 
are taken along till they are rubbed off by some gravel bar or fall down by the melting of the ice; 
the next season, if on a bar and near the surface, they again become frozen up with the ice and 
are moved farther down. Thus they are constantly working their way down the river, and a bar 
that this season is encumbered by them may be free the next. 
Conclusions with regard to Navigation. 
From the above statements it will be seen that the only obstructions to the navigation of the 
river by steamboats are the shallowness of the water and the large boulders in the channel. But 
the first does not exist as an obstruction to boats drawing twenty inches, before the middle of 
September. As to the second obstruction, it can, I think, be obviated by providing a boat with 
suitable grappling-hooks, with which she can hitch on to a rock in her way, and drop down with 
it to deeper water, with but very little detention. A boat drawing twenty inches, loaded, can 
then, I think, navigate the river from the opening of the season till the first of September with 
perfect safety. Earlier in the season it is quite probable that boats of three feet draught would 
find no difficulty in ascending, but, in order to be here in time, they would have to winter at Fort 
Union. This fact, therefore, becomes of no practical advantage at present. As to wood for the 
use of boats, plenty of it can be found upon the banks. 
A steamer of eighteen inches draught could, in my opinion, ascend the river at any time. 
C. GROVER, 
Second Lieutenant Fourth Artillery. 
Governor I. I, Srevens. 
