HYDROGRAPHIC REPORT. 9 
to insure the vessel from grounding at the lowest tide. In this part of the river, owing to the 
formation of the steep shelving banks and the rapid rise and fall of the water, it would be 
difficult and dangerous to land freight from the vessel directly upon the shore. The best course 
would be to ascend the river for twenty or thirty miles. It would be impossible to sail up. 
The vessel should take advantage of the tides, and, an hour or two after the passage of the 
‘‘bore,’’ or the setting in of the flood, drift along the channel, keeping near the highest bank, 
and constantly sounding; care being taken to select a secure place for an anchorage before the 
approach of the ebb. The time of high water at ‘‘full and change’’ is, at the mouth of the 
Colorado, 3h. 15m., p. m. 
When a steamboat is to be built for service upon the river the materials should be carried 
at least twenty-five miles above the mouth, in order to secure a place not overflowed at the 
highest tides, to be beyond the effects of the bore, and to be near fresh water. 
Enough drift-wood can be found strewed over the flats to afford a supply of fuel, and some 
miles higher up there is a growth of cottonwood, willow, and mesquite along the banks, but 
the country furnishes no timber suitable to be used in building a boat, or even material of 
which the ways could be constructed.* 
MOUTH OF THE COLORADO TO FORT YUMA. 
It is about one hundred and fifty miles by the river from the head of the Gulf to Fort Yuma, 
though only half that distance in a direct line. Concerning no particular locality can any 
special information be given that would be of value to the navigator. The shifting of the 
channel, the banks, the islands, and the bars is so continual and so rapid that a detailed 
description, derived from the experiences of one trip, would be found incorrect, not only during 
the subsequent year, but perhaps in the course of a week, or evena day. A few facts of a 
general character can alone be stated. 
The width of this portion of the river varies from one-eighth to half a mile. The course is 
exceedingly tortuous. The depth in the channel is from eight to twenty feet, but bars are 
frequently encountered where there are not more than two feet of water. The current, during 
the low stage of the river, which is from October till the early part of May, has an average 
velocity of two and a half miles an hour. In some of the bends it is perhaps a mile an hour 
swifter. The period of highest water is in the early part of July, when this velocity is 
increased to five or six miles. The average height is then ten feet greater than during the 
summer months, but the depth is not in all places proportionally increased. New bars at once 
form when the river begins to rise, and the obstructions to navigation, though not as numerous, 
are still encountered. 
No rocks are met with below Fort Yuma. The bed of the river is composed of quicksand 
and soft clay. The bars are yielding, and any agitation upcn their surface causes them speedily 
to wash away. <A boat may frequently be forced over places where there was, at the time of 
its striking, six or eight inches too little water. , ; 
For several years the Colorado has been regularly navigated by steamboats between its 
mouth and Fort Yuma. At low water trips are rarely made without the boat grounding many 
times a day. A sounding pole is constantly employed. Different points upon the bar are tried 
till the least difficult is found. The steamer is then worked backwards and forwards to loosen 
the sand. Lines are attached to a tree, snag, or to an anchor taken out ahead, and are heaved 
upon with the windlass or capstan. As a last resource the boat is lightened of a portion of the 
cargo, and by these expedients the bars may always be passed, with more or less difficulty and 
®The above information has been gathered from my own observations, from the report of Lieutenant Derby, Topograph- 
ica) Engineers, from Captain C. P. Stone, of the Sonora survey, from Captains Johnson and Wilcox of the Colorado steam- 
boat company, and from Captains Naghel, Jayne, and Walsh, who have commanded vessels running from San Francisco to 
the mouth of the Colorado. 
K 
